anbinh / hapi

Node.js HTTP Server framework

A rich framework for building restful API services. hapi is a configuration-centric framework in which authentication requirements, input validation, data caching and pre-fetching, developer documentation, and other essential facilities are provided out-of-the-box and enabled using simple JSON configuration objects. hapi enables developers to focus on writing reusable business logic instead of spending time with everything else.

Current version: 0.12.0

Table of Content

• Usage
  • Basic Usage

- [**Server Construction**](#server-construction)

- [**Server Configuration**](#server-configuration) - [TLS](#tls) - [Router](#router) - [Payload](#payload) - [Extensions](#extensions) - [Format](#format) - [Error Format](#error-format) - [Payload Format](#payload-format) - [Files](#files) - [Views](#views) - [Monitor](#monitor) - [Authentication](#authentication) - [Cache](#cache) - [Debug](#debug) - [CORS](#cors) - [Batch](#batch) - [State](#state) - [Timeout](#timeout)

- [**Server Events**](#server-events)

- [**Server Route Not Found**](#server-route-not-found)

- [**Route Configuration**](#route-configuration) - [Configuration options](#configuration-options) - [Override Route Defaults](#override-route-defaults) - [Path Processing](#path-processing) - [Route Matching Order](#route-matching-order) - [Parameters](#parameters) - [Route Handler](#route-handler) - [Response](#response) - [Proxy](#proxy) - [File](#file) - [Directory](#directory) - [View](#view) - [Docs](#documentation) - [Request Logging](#request-logging) - [Not Found](#not-found-handler) - [Route Authentication](#route-authentication) - [Query Validation](#query-validation) - [Payload Validation](#payload-validation) - [Path Validation](#path-validation) - [Response Validation](#response-validation) - [Caching](#caching) - [Prerequisites](#prerequisites)

- [**Data Validation**](#data-validation)

- [**Response Errors**](#response-errors)

- [**State Management**](#state-management) - [Raw Cookies](#raw-cookies)

- [**General Events Logging**](#general-events-logging)

- [**Request Tails**](#request-tails)

- [**Request Injection**](#request-injection)

- [**Server Helpers**](#server-helpers)

Usage

Basic Usage

The following is a simple "hello world" service with a single API endpoint:

var Hapi = require('hapi');

// Create a server with a host and port
var server = new Hapi.Server('localhost', 8000);

// Define the route
var hello = {
    handler: function (request) {
    
        request.reply({ greeting: 'hello world' });
    }
};

// Add the route
server.addRoute({
    method: 'GET',
    path: '/hello',
    config: hello
});

// Start the server
server.start();

Now navigate to http://localhost:8000/hello and you should receive 'hello world'.

Server Construction

The hapi Server object is the core of the framework and is constructed by instantiating a new Server object with the following optional parameters:

• 'host' - optional host name. Defaults to 'localhost'.
• 'port' - optional port. Defaults to '80' (or '443' for TLS).
• 'options' - optional configuration as described in Server Configuration.

var Hapi = require('hapi');

// Create a server on localhost port 80
var server = new Hapi.Server();

Server Configuration

hapi provides a rich set of configuration options for each server instance:

• tls
• router
• payload
• ext
• format
• files
• monitor
• authentication
• cache
• debug
• cors
• batch
• state

TLS

hapi creates an HTTP server by default. To create an HTTPS server, include the tls object in the server configuration. The tls object is passed unchanged to the node.js HTTPS server and described in the node.js HTTPS documentation.

var Hapi = require('hapi');

var options = {
    tls: {
        key: 'your_key',
        cert: 'your_cert'
    }
};

var server = new Hapi.Server(options);

Router

The router option controls how incoming request URIs are matched against the routing table. The router only uses the first match found. Router options:

• isCaseSensitive - determines whether the paths '/example' and '/EXAMPLE' are considered different resources. Defaults to true.
• normalizeRequestPath - determines whether a path should have certain reserved and unreserved percent encoded characters decoded. Also, all percent encodings will be capitalized that cannot be decoded. Defaults to false.

Payload

The payload option controls how incoming payloads (request body) are processed. Payload options:

• maxBytes - limits the size of incoming payloads to the specified bytes count. Allowing very large payloads may cause the server to run out of memory. Defaults to 1MB.

Extensions

hapi does not support middleware extensibility as is commonly found in other web frameworks. Instead, hapi provides extension hooks for any application-specific functionality. Each extension point accepts a single function or an array of functions to be executed at a specified stage during request processing. The required extension function signature is function (request, next) where:

• 'request' is the hapi request object, and
• 'next' is the callback function the method must call upon completion to return control over to the router.

The extension points are:

• onRequest - called upon new requests before any router processing. The 'request' object passed to the onRequest functions is decorated with the 'setUrl(url)' and _'setMethod(verb)' methods. Calls to these methods will impact how the request is router and can be used for rewrite rules.
• onPreHandler - called after request passes validation and body parsing, before the request handler.
• onPostHandler - called after the request handler, before sending the response. The actual state of the response depends on the response type used (e.g. direct, stream).
• onPostRoute - called after the response was sent.
• onUnknownRoute - if defined, overrides the default unknown resource (404) error response. The method must send the response manually via request.raw.res. Cannot be an array.

For example:

var Hapi = require('hapi');

var options = {
    ext: {
        onRequest: onRequest
    }
};

// Create server
var http = new Hapi.Server('localhost', 8000, options);

// Set routes
http.addRoute({ method: 'GET', path: '/test', handler: get });

// Start server
http.start();

// Resource handler
function get(request) {

    request.reply({ status: 'ok' });
}

// Path rewrite
function onRequest(request, next) {

    // Change all requests to '/test'
    request.setUrl('/test');
    next();
}

Format

The format option provides an extension point for use of custom methods to format error responses or payloads before they are sent back to the client.

Error Format

If a different error format than the default JSON response is required, the server format.error option can be assigned a function to generate a different error response. The function signature is 'formatted = function (result)' where:

• 'result' - is the hapi error object returned by the route handler, and
• 'formatted' - is the formatted response object which contains the following keys:
  • code - the HTTP status code.
  • payload - the response payload.
  • type - the response payload content-type.
  • headers - any additional response HTTP headers (object).

Note that the format function must be synchronous.

For example:

var options = {
    format: {
        error: function (result) {
        
            return { code: 500, payload: 'Oops: ' + result.message, type: 'text/html' };
        }
    }
};

Payload Format

In cases where every non-error payload has to be processed before being sent out (e.g. when returning a database object and need to hide certain fields or rename '_id' to 'id'), the `format.payload' option can be set to a function that is called on every result, immediately after 'request.reply' is called. The function's signature is 'formatted = function (result)' where:

• 'result' - is the raw result object returned by the route handler, and
• 'formatted' - is the formatted response to replace 'result'.

Note that the format function must be synchronous, and it is only invoked for response types other than Stream.

For example:

var options = {
    format: {
        payload: function (result) {
        
            return 'something else instead';
        }
    }
};

Views

To enable Views support, Hapi must be given an options object with a non-null views key. The views object supports the following options:

• path - (Required) the root file path where the request.reply.view function will resolve template names.
• engine - the configuration for what template rendering engine will be used (default: handlebars).
  • module - the npm module to require and use to compile templates (this is experimental and may not not work with all modules).
  • extension - the file extension used by template files.
• engines - optional configuration for supporting multiple rendering engines
  • module - the npm module to require and use
• partials - this key enables partials support if non-null.
  • path - the root file path where partials are located (if different from views.path).
• layout - if set to true, layout support is enabled (default: false).
• layoutKeyword - the key used by the template engine to denote where primary template content should go.
• encoding - the text encoding used by the templates.
• cache - if set to false, templates will not be cached (thus will be read from file on every use).
• allowAbsolutePaths - the flag to set if absolute template paths passed to .view() should be allowed.
• allowInsecureAccess - the flag to set if ../ should be allowed in the template paths passed to .view().
• compileOptions - the options object passed to the engine's compile function (compile(string, options)).

Files

hapi provides built-in support for serving static files and directories as described in File and Directory. When these handlers are provided with relative paths, the files.relativeTo server option determines how these paths are resolved and defaults to 'routes':

• 'routes' - relative paths are resolved based on the location of the files in which the server's 'addRoute()' or 'addRoutes()' methods are called. This means the location of the source code determines the location of the static resources when using relative paths.
• 'process' - relative paths are resolved using the active process path ('process.cwd()').

Monitor

hapi comes with a built-in process monitor for three types of events:

• System and process performance (ops) - CPU, memory, disk, and other metrics.
• Requests logging (request) - framework and application generated logs generated during the lifecycle of each incoming request.
• General events (log) - logging information not bound to a specific request such as system errors, background processing, configuration errors, etc. Described in General Events Logging.

The monitor is off by default and can be turned on using the monitor server option. To use the default settings, simply set the value to true. Applications with multiple server instances, each with its own monitor should only include one log subscription per destination as general events (log) are a process-wide facility and will result in duplicated log events. To override some or all of the defaults, set monitor to an object with the following optional settings:

• broadcastInterval - the interval in milliseconds to send collected events to subscribers. 0 means send immediately. Defaults to 0.
• opsInterval - the interval in milliseconds to sample system and process performance metrics. Minimum is 100ms. Defaults to 15 seconds.
• extendedRequests - determines if the full request log is sent or only the event summary. Defaults to false.
• requestsEvent - the event type used to capture completed requests. Defaults to 'tail'. Options are:
  • 'response' - the response was sent but request tails may still be pending.
  • 'tail' - the response was sent and all request tails completed.
• subscribers - an object where each key is a destination and each value an array subscriptions. Subscriptions available are ops, request, and log. The destination can be a URI or console. Defaults to a console subscription to all three. To disable the console output for the server instance pass an empty array into the subscribers "console" configuration.

For example:

var options = {
    monitor: {
        subscribers: {
            console: ['ops', 'request', 'log'],
            'http://localhost/logs': ['log']
        }
    }
};

Disabling hapi console output:

var options = {
    monitor: {
        subscribers: {
            console: [],
            'http://localhost/logs': ['log']
        }
    }
};

Authentication

The authentication interface is disabled by default and is still experimental.

Hapi supports several authentication schemes and can be configured with different authentication strategies that use these schemes. Authentication is configured for the server by either assigning a single strategy to the 'auth' object or by creating an object with different strategies where the strategy names are the object keys.

• scheme - when using a single authentication strategy set this to the configuration options for that strategy
• implementation - when using a custom scheme set this to the function that will perform authentication. Scheme must start with 'ext:' when using a custom implementation.

When the server supports multiple authentication strategies then you can set strategies on the 'auth' object directly where the strategy name is the object key. Every strategy object on the 'auth' object should follow the same guidelines as above.

Basic Authentication

Enabling and using basic authentication with hapi is straightforward. Basic authentication requires validating a username and password combination. Therefore, a prerequisite to using basic authentication is to have a function that will return the user information given the username. The signature for this function is shown below:

function (username, callback)  // callback is a function that expects (err, { id, password })

Next setup the 'auth' server settings to look similar to the following:

auth: {
    scheme: 'basic',
    loadUserFunc: function (username, callback) { 
        
        var user = { id: '', password: '' };
        callback(null, user);
    }
}

Please note that the 'loadUserFunc' callback expects a user object with an 'id' and 'password' property. The 'id' should match the incoming username in the request.

After basic authentication is setup any request that has the 'Authentication' header using the 'Basic' scheme will validate the username and password.

If you wish to hash the password found in the header before being compared to the one found in the database you can assign a function to the 'hashPasswordFunc' property. Below is an example of a hashPassword function.

var hashPassword = function (password, user) {
    
    var hash = Crypto.createHash('sha1');
    hash.update(password, 'utf8');
    hash.update(user.salt, 'utf8');

    return hash.digest('base64');
}

Hawk Authentication

The hawk authentication scheme can be enabled similarly to basic authentication. Hawk requires a function that takes an 'id' and passes credentials to the callback. Below is an example of a function like this and using it with hapi.

var Hapi = require('hapi');

var credentials = {
    'john': {
        cred: {
            id: 'john',
            key: 'werxhqb98rpaxn39848xrunpaw3489ruxnpa98w4rxn',
            algorithm: 'sha256'
        }
    }
}

var getCredentials = function (id, callback) {
   
    return callback(null, credentials[id] && credentials[id].cred);
};

var config = {
    auth: {
        scheme: 'hawk',
        getCredentialsFunc: getCredentials
    }
};

var server = new Hapi.Server(config);

In the above example only the user 'john' can authenticate, all other users will result in an error.

Multiple Authentication Strategies

There may be instances where you want to support more than one authentication strategy for a server. Below is an example of using both basic and hawk authentication strategies on the server and defaulting to basic. The default strategy is what will be used by endpoints if they do not specify a strategy to use.

 var config = {
    auth: {
        'default': {
            scheme: 'basic',
            loadUserFunc: internals.loadUser,
            hashPasswordFunc: internals.hashPassword
        },
        'hawk': {
            scheme: 'hawk',
            getCredentialsFunc: internals.getCredentials
        },
        'basic': {
            scheme: 'basic',
            loadUserFunc: internals.loadUser,
            hashPasswordFunc: internals.hashPassword
        }
    }
};

In the 'examples' folder is an 'auth.js' file that demonstrates creating a server with multiple authentication strategies.

Cache

hapi provides a built-in caching facility for storing and reusing request responses and helpers utilities. The provided implementations include Redis and MongoDB support (each must be manually installed and configured). The cache functionality is off by default. To enable caching, the cache option must be set to an object with the following options:

• engine - the cache server implementation. Options are redis, mongodb, and memory.
• host - the cache server hostname.
• port - the cache server port.
• partition - the partition name used to isolate the cached results across different servers. Defaults to 'hapi-cache'.
• username, password, poolSize - MongoDB-specific options.

For convenience, pre-configured options are provided for Redis, MongoDB, and an experimental memory store. To use them, simply set the server's cache option to:

• 'redis' - Connects to 127.0.0.1:6379 using partition name 'hapi-cache'.
• 'mongodb' - Connects to 127.0.0.1:27017 using partition name 'hapi-cache', no authentication, and pool size 5.
• 'memory' - This is an experimental engine and should be avoided in production environments. The memory engine will run within the node process and supports the following option:
  • maxByteSize - Sets an upper limit on the number of bytes that can be consumed by the total of everything cached in the memory engine. Once this limit is reached no more items will be added to the cache.

For example:

var options = {
    cache: 'redis'
};

Enabling the server cache only creates the cache interface but does not enable caching for any individual routes or helpers, which must be enabled and configured in the route or helper configuration.

Debug

To assist in debugging server events related to specific incoming requests, hapi includes an optional debug console which is turned off by default. The debug console is a simple web page in which developers can subscribe to a debug id, and then include that debug id as an extra query parameter in each request. The server will use WebSocket to stream the subscribed request logs to the web page in real-time. In application using multiple server instances, only one can enable the debug interface using the default port. To enable the debug console set the debug option to true or to an object with custom configuration:

• websocketPort - the port used by the WebSocket connection. Defaults to 3000.
• debugEndpoint - the debug console request path added to the server routes. Defaults to '/debug/console'.
• queryKey - the name or the request query parameter used to mark requests being debugged. Defaults to debug.

CORS

The Cross-Origin Resource Sharing protocol allows browsers to make cross-origin API calls. This is required by web application running inside a browser which are loaded from a different domain than the API server. hapi provides a general purpose CORS implementation that sets very liberal restrictions on cross-origin access by default (off by default). CORS options:

• origin - overrides the array of allowed origin servers ('Access-Control-Allow-Origin'). Defaults to any origin '*'.
• maxAge - number of seconds the browser should cache the CORS response ('Access-Control-Max-Age'). The greater the value, the longer it will take before the browser checks for changes in policy. Defaults to one day.
• headers - overrides the array of allowed headers ('Access-Control-Allow-Headers'). Defaults to 'Authorization, Content-Type, If-None-Match'.
• additionalHeaders - an array of additional headers to headers. Use this to keep the default headers in place.
• methods - overrides the array of allowed methods ('Access-Control-Allow-Methods'). Defaults to 'GET, HEAD, POST, PUT, DELETE, OPTIONS'.
• additionalMethods - an array of additional methods to methods. Use this to keep the default methods in place.
• credentials - if true, allows user credentials to be sent ('Access-Control-Allow-Credentials'). Defaults to false.

Batch

The batch endpoint makes it easy to combine requests into a single one. It also supports pipelining so you are able to take the result of one of the endpoints in the batch request and use it in a subsequent endpoint. The batch endpoint only responds to POST requests. By default the batch endpoint is turned off. To enable the batch endpoint set the batch option to true or to an object with the following custom configuration:

• batchEndpoint - the path where batch requests will be served from. Default is '/batch'.

As an example to help explain the use of the endpoint, assume that the server has a route at '/currentuser' and '/users/{id}/profile/'. You can make a POST request to the batch endpoint with the following body: { "requests": [ {"method": "get", "path": "/currentuser"}, {"method": "get", "path": "/users/$0.id/profile"} ] } and it will return an array with the current user and their profile.

The response body to the batch endpoint is an ordered array of the response to each request. Therefore, if you make a request to the batch endpoint that looks like { "requests": [ {"method": "get", "path": "/users/1"}, {"method": "get", "path": "/users/2"} ] } the response might look like: [{"userId": "1", "username": "bob"}, {"userId": "2", "username": "billy" }] where the first item in the response array is the result of the request from the first item in the request array.

If an error occurs as a result of one the requests to an endpoint it will be included in the response in the same location in the array as the request causing the issue. The error object will include an error property that you can interrogate. At this time the response is a 200 even when a request in the batch returns a different code.

*** At this time batch only supports requests to routes that use the GET method.

State

HTTP state management (cookies) allows the server to store session information on the client which is sent back to the server with every request (as defined in RFC 6265). hapi will automatically parse incoming cookies based on the server's state.cookies configuration, where:

• parse - determines is incoming 'Cookie' headers are parsed and stored in the 'request.cookies' object. Defaults to true.
• 'failAction' - allowed values are: 'error' (return 500), 'log' (report error but continue), or 'ignore' (continue) when a request cookie fails parsing. Defaults to 'error'.

Timeout

The 'timeout' object can contain a 'server' and 'client' timeout value in milliseconds. These are useful for limiting the amount of time a request or response should take to complete.

Server Timeout

In order to indicate when a server or dependent services are overwhelmed set the 'timeout.server' property. This property should be set to the maximum number of milliseconds to allow a server response to take before responding with a 503 status code. By default 'timeout.server' is disabled.

The server timeout is measured as the time from executing a hapi request until a response is generated for the request and validated. If an endpoint takes longer than the timeout to generate a response the response will not be cached.

The example below demonstrates how to force the server to timeout when it takes the server longer than 10 seconds to begin responding to a request: { timeout: { server: 10000 } }

Client Timeout

In order to indicate to a client that they are taking too long to send a request the 'timeout.client' option should be set. By default this value is set to 10000 ms. As a result, any request taking longer than 10 seconds to complete will error out with a 408 status code. Below is an example of disabling the client timeout: { timeout: { client: false } }

Server Events

The server object emits the following events:

• 'response' - emitted after a response is sent back. Includes the request object as value.
• 'tail' - emitted when a request finished processing, including any registered tails as described in Request Tails.

Server Route Not Found

hapi provides a default handler for unknown routes (HTTP 404). If the application needs to override the default handler, it can use the setNotFound server method. The method takes a route configuration object with a handler property.

Below is an example creating a server and then setting the 'notFound' route configuration.

For example, the default notFound route configuration can be set as shown below:

var Hapi = require('hapi');

// Create server
var http = new Hapi.Server(8000);

// Set the notFound route configuration
http.setNotFound({ handler: notFoundHandler });

// Start server
http.start();

// 404 handler
function notFoundHandler(request) {

    request.reply(Hapi.Error.notFound('The page was not found'));
}

Route Configuration

hapi was designed to move as much logic as possible from the route handler to the route configuration. The goal is to provide a simple mechanism for defining routes without having to write code. This approach also enables producing dynamic route documentation without having to write additional text as the configuration itself serves as a living documentation.

Configuration options

• path - the absolute path or regular expression to match against incoming requests. Path comparison is configured using the server router option. String paths can include named identifiers enclosed in '{}' as described in Path Parameters.
• method - the HTTP method. Typically one of 'GET, POST, PUT, DELETE, OPTIONS'. Any HTTP method is allowed, except for 'HEAD'. hapi does not provide a way to add a route to all methods.
• handler - the business logic function called after authentication and validation to generate the response. The function signature is function (request) where 'request' is the hapi request object. See Route Handler for more information. Optionally, this can be an object with a 'proxy', 'file', or 'directory' property:
  • proxy - generates a reverse proxy handler as described in (Proxy)[#proxy].
  • file - generates a static file endpoint as described in (File)[#file].
  • directory - generates a directory mapper for service static content as described in (Directory)[#directory].
• config - route configuration grouped into a sub-object to allow splitting the routing table from the implementation details of each route. Options include:
  • description - route description.
  • notes - route notes (string or array of strings).
  • tags - route tags (array of strings).
  • handler - an alternative location for the route handler function. Same as the handler option in the parent level. Can only include one handler per route.
  • validate
    • query - validation rules for incoming requests' query component (the key-value part of the URI between ? and #). Defaults to any query parameters being allowed. See Query Validation for more information.
    • schema - validation rules for incoming requests' payload (request body). Defaults to no validation (any payload allowed). Set to 'false' to forbid payloads. See Payload Validation for more information.
    • path - validation rules for incoming requests' path parameters. Defaults to no validation (any path parameter allowed). Set to 'false' to forbid any path parameter. See Path Validation for more information.
  • response - validation rules for outgoing responses' payload (response body). Defaults to no validation (any payload allowed). Set to an empty object '{}' to forbid payloads. See Response Validation for more information.
  • payload - determines how the request payload is processed. Defaults to 'parse' if schema is present or method is 'POST' or 'PUT', otherwise 'stream'. Payload processing is configured using the server payload option. Options are:
    • 'stream' - the incoming request stream is left untouched, leaving it up to the handler to process the request via 'request.raw.req'. Note that the request readable stream is put in a paused state and must be resumed before it will emit data events.
    • 'raw' - the payload is read and stored in 'request.rawBody' but not parsed.
    • 'parse' - the payload is read and stored in 'request.rawBody' and then parsed (JSON or form-encoded) and stored in 'request.payload'.
  • cache - if the server cache option is enabled and the route method is 'GET', the route can be configured to use the cache as described in Caching.
  • docs - if set to false then the route will be hidden from the documentation generator.
  • pre - an array with pre-handler methods as described in Route Prerequisites.
  • auth - authentication configuration
    • mode - the authentication mode. Defaults to 'required' is the authentication server option is set, otherwise 'none'. Available options include:
      • 'none' - authentication not allowed.
      • 'required' - authentication is required.
      • 'optional' - authentication is optional (validated if present).
    • tos - minimum terms-of-service version required. This is compared to the terms-of-service version accepted by the user. Defaults to none.
    • scope - required application scope. Defaults to none.
    • entity - the required authenticated entity type. Not supported with every authorization scheme. Available options include:
      • 'any' - the authentication can be on behalf of a user or application.
      • 'user' - the authentication must be on behalf of a user.
      • 'app' - the authentication must be on behalf of an application.

The config option was defined for easily spliting the routing table definition from the individual route information. For example:

var Hapi = require('hapi');

var server = new Hapi.Server();

// Option 1 - add handler directly in route definition

var handler1 = function (request) {

    request.reply('ok');
}

server.addRoute({ method: 'GET', path: '/option1', handler: handler1 });

// Option 2 - add handler in separate config object

var config2 = {
    payload: 'raw',
    // ... additional config options ...
    handler: function (request) {

        request.reply('ok');
    }
};

server.addRoute({ method: 'GET', path: '/option2', config: config2});

Override Route Defaults

Each configuration option comes with a built-in default. To change these defaults, use the setRoutesDefaults() server method.

server.setRoutesDefaults({
    auth: { mode: 'none' }
});

Path Processing

The hapi router iterates through the routing table on each incoming request and executes the first (and only the first) matching route handler. Route matching is done on the request path only (excluding the query and other components). The route path option support three types of paths:

• Static - the route path is a static string which begin with '/' and will only match incoming requests containing the exact string match (as defined by the server router option).
• Parameterized - same as static with the additional support of named parameters (enclosed in '{}').

Route Matching Order

hapi matches incoming requests in a deterministic order. This means the order in which routes are added does not matter. To achieve this, hapi uses a set of rules to sort the routes from the most specific to the most generic. For example, the following path array shows the order in which an incoming request path will be matched against the routes, regardless of the order they are added:

var paths = [
    '/',
    '/a',
    '/b',
    '/ab',
    '/{p}',
    '/a/b',
    '/a/{p}',
    '/b/',
    '/a/b/c',
    '/a/b/{p}',
    '/a/{p}/b',
    '/a/{p}/c',
    '/a/{p*2}',
    '/a/b/c/d',
    '/a/b/{p*2}',
    '/a/{p}/b/{x}',
    '/{p*5}',
    '/a/b/{p*}',
    '/{p*}'
];

Parameters

Parameterized paths are processed by matching the named parameters to the content of the incoming request path at that level. For example, the route: '/book/{id}/cover' will match: '/book/123/cover' and 'request.params.id' will be set to '123'. Each path level (everything between the opening '/' and the closing '/' unless it is the end of the path) can only include one named parameter. The '?' suffix following the parameter name indicates an optional parameter (only allowed if the parameter is at the ends of the path). For example: the route: '/book/{id?}' will match: '/book/'.

server.addRoute({
    path: '/{album}/{song?}',
    method: 'GET',
    handler: getAlbum
});

function getAlbum(request) {

    request.reply('You asked for ' +
                  (request.params.song ? request.params.song + ' from ' : '') +
                  request.params.album);
}

In addition to the optional '?' suffix, a param can also specify an expected number of parts in the path. To do this use the '*' suffix followed by a number greater than 1. If the number of expected parts can be anything, then use the '*' without a number.

server.addRoute({
    path: '/person/{names*2}',
    method: 'GET',
    handler: getPerson
});

function getPerson(request) {

    var nameParts = request.params.names.split('/');
    request.reply(new Person(namesParts[0], nameParts[1]));
}

In the example code above if a request for /person/john/smith comes in then request.params.names is set to 'john/smith'. In this example a person will be returned for the john smith.

Below is a similar example without a requirement on the number of name parts that can be passed.

server.addRoute({
    path: '/people/{names*}',
    method: 'GET',
    handler: getPerson
});

function getPeople(request) {

    var nameParts = request.params.names.split('/');
    request.reply(loadPeople(namesParts));
}

In the example people are loaded by passing in a names array. If a request comes in for people/john/bob/jenny then request.params.names is set to 'john/bob/jenny'. Please note that the route will be matched for a request of /people/ as names can be 0 or more parts. As a result of this behavior, {names*} must appear as the last parameter in the route path. In other words, a param with 0 or more path parts must appear at the end of the end of the route path.

Route Handler

When the provided route handler method is called, it receives a request object with the following properties:

• 'url' - the parsed request URI.
• 'path' - the request URI's path component.
• 'method' - the request method as a lowercase string. (Examples: 'get', 'post').
• 'query' - an object containing the query parameters.
• 'params' - an object containing the path named parameters as described in Path Parameters.
• 'rawBody' - the raw request payload (except for requests with config.payload set to 'stream').
• 'payload' - an object containing the parsed request payload (for requests with config.payload set to 'parse').
• 'state' - an object containing parsed HTTP state information (cookies).
• 'session' - available for authenticated requests and includes:
  • 'id' - session identifier.
  • 'used' - user id (optional).
  • 'app' - application id (optional).
  • 'scope' - approved application scopes (optional).
  • 'ext.tos' - terms-of-service version (optional).
• 'server' - a reference to the server object.
• 'pre' - any requisites as described in Prequisites.
• 'addTail([name])' - adds a request tail as described in Request Tails.
• 'raw' - an object containing the Node HTTP server 'req' and 'req' objects. Direct interaction with these raw objects is not recommended.

In addition, the handler method is bound to the request object which is also available using this:

var handler = function () {

    this.reply('Hello ' + this.params.user);
};

Response

hapi provides native support for the following response types:

• Empty - an empty response body (content-lenght of zero).
• Text - plain text. Defaults to 'text/html' content-type.
• Obj - Javascript object, converted to string. Defaults to 'application/json' content-type.
• Stream - a stream object, directly piped into the HTTP response.
• File - transmits a static file. Defaults to the matching mime type based on filename extension.
• Direct - special response type for writing directly to the response object. Used for chunked responses.
• Error - error objects generated using the 'Hapi.error' module or 'new Error()' described in Response Errors.

The request object includes a 'reply' property which includes the following methods:

• 'payload(result)' - sets the provided 'result' as the response payload. 'result' cannot be a Stream. The method will automatically identify the result type and cast it into one of the supported response types (Empty, Text, Obj, or Error). 'result' can all be an instance of any other response type provided by the 'Hapi.response' module (e.g. File, Direct).
• 'stream(stream)' - pipes the content of the stream into the response.
• 'redirect(uri)' - sets a redirection response. Defaults to 302.
• 'send()' - finalizes the response and return control back to the router. Must be called after 'payload()' or 'stream()' to send the response.

For convenience, the 'response' object is also decorated with a shortcut function 'reply([result])' which is identical to calling 'reply.payload([result]).send()' or 'reply.stream(stream).send()'.

The 'payload()', 'stream()', and 'redirect()' methods return a hapi Response object created based on the result item provided. Depending on the response type, additional chainable methods are available:

• 'created(location)` - a URI value which sets the HTTP response code to 201 (Created) and adds the HTTP Location header with the provided value (normalized to absolute URI). Not available with 'redirect()'.
• 'bytes(length)' - a pre-calculated Content-Length header value. Only available when using 'pipe(stream)'.
• 'type(mimeType)' - a pre-determined Content-Type header value. Should only be used to override the built-in defaults.
• 'ttl(msec)' - a milliseconds value which overrides the default route cache expiration rule for this individual response.
• 'state(name, value, options)' - sets an HTTP state (cookie) as described in Raw Cookies
• 'unstate(name)' - instructs the client to remove the HTTP state.

The following methods are only available when using 'redirect()':

• 'message(text, type)' - a payload message and optional content type (defaults to 'text/html').
• 'uri(dest)' - the destination URI.
• 'temporary()' - sets the status code to 302 or 307 (based on the rewritable settings). Defaults to 'true'.
• 'permanent()' - sets the status code to 301 or 308 (based on the rewritable settings). Defaults to 'false'.
• 'rewritable(isRewritable)' - sets the status code to 301/302 (based on the temporary settings) for rewritable (change POST to GET) or 307/308 for non-rewritable. Defaults to 'true'.

The handler must call 'reply()', 'reply.send()', or 'reply.payload/stream()...send()' (and only one, once) to return control over to the router. The reply methods are only available within the route handler and are disabled as soon as control is returned.

Proxy

It is possible with hapi to setup a reverse proxy for routes. This is especially useful if you plan to stand-up hapi in front of an existing API or you need to augment the functionality of an existing API. Additionally, this feature is powerful in that it can be combined with caching to cache the responses from external APIs. The proxy route configuration has the following options:

• passThrough - determines if the headers sent from the clients user-agent will be forwarded on to the external service being proxied to (default: false)
• xforward - determines if the x-forward headers will be set when making a request to the proxied endpoint (default: false)
• host - The host to proxy requests to. The same path on the client request will be used as the path to the host.
• port - The port to use when making a request to the host.
• protocol - The protocol to use when making a request to the proxied host (http or https)
• mapUri - A function that receives the clients request and a passes the URI to a callback to make the proxied request to. If host is set mapUri cannot be used, set either host or mapUri.
• postResponse - A function that will be executed before sending the response to the client for requests that can be cached. Use this for any custom error handling of responses from the proxied endpoint.
• httpClient - A function that should make the request to the remote server and use execute the callback with a response. By default this uses 'request' as the module. The signature is (options, callback) where options will contain a url and method.

For example, to proxy a request to the homepage to google:

// Create Hapi servers
var http = new Hapi.Server('0.0.0.0', 8080);

// Proxy request to / to google.com
http.addRoute({ method: 'GET', path: '/', handler: { proxy: { protocol: 'http', host: 'google.com', port: 80 } } });

http.start();

File

File handlers provide a simple way to serve a static file for a given route. This is done by specifying an object with the file option as the route handler. The value of the file option is the absolute or relative path to the static resource. Relative paths are resolved based on the server's files option as described in (Files)[#files]. The route path cannot contain parameters when configured with a static file path. For example:

// Create Hapi server
var http = new Hapi.Server('0.0.0.0', 8080, { files: { relativeTo: 'process' } });

// Serve index.html file up a directory in the public folder
http.addRoute({ method: 'GET', path: '/', handler: { file: './public/index.html' } });

http.start();

The file handler also supports dynamic determination of the file being served based on the request, using a function as the value of the file option with the signature 'function (request) { return './path'; }'. The function is passed the request object and must return a string with the relative or absolute path to the static resource. For example:

// Create Hapi server
var http = new Hapi.Server('0.0.0.0', 8080);

// File mapping function
var filePath = function (request) {

    if (isMobileDevice(request)) {
        return './mobile/' + request.params.path;
    }

    return './public' + request.params.path;
};

http.addRoute({ method: 'GET', path: '/{path}', handler: { file: filePath } });

http.start();

Directory

Directory handlers provide a flexible way to serve static content from an entire directory tree. Similar to other web servers, hapi allows mapping between a request path component to resources within a file system directory, including serving a default index.html or a directory content listing.

Routes utilizing the directory handler must include a single path parameter at the end of the path string (e.g. '/path/to/somewhere/{param}'). The directory handler is an object with the following options:

• path - a required path string or function. If the path is a string, it is used as the prefix for any resources requested within the route by appending the required route path parameter to the provided string. Alternatively, the path can be a function with the signature 'function (request) { return './path'; }'. The function is passed the request object and must return a string with the relative or absolute path to the static resource. Relative paths are resolved based on the server's files option as described in (Files)[#files].
• index - optional boolean, determines if 'index.html' will be served if exists in the folder when requesting a directory. Defaults to 'true'.
• listing - optional boolean, determines if directory listing is generated when a directory is requested without an index document. Defaults to 'false'.
• showHidden - optional boolean, determines if hidden files will be shown and served. Defaults to 'false'.

The required route path parameter can use any of the parameter options (e.g. '{param}', '{param?}', '{param*}'). For example, to server only files in the top level folder and not to any subfolder use '{path?}'. If it is safe to navigate to child folders and files then use '{path*}'. Similarly, if the server should only allow access to a certain level of subfolders then use '{path*2}'.

The following example shows how to serve a directory named 'public' and enable a directory listing in case a 'index.html' file doesn't exist:

// Create Hapi server
var http = new Hapi.Server('0.0.0.0', 8080);

// Serve the public folder with listing enabled
http.addRoute({ method: 'GET', path: '/{path*}', handler: { directory: { path: './public/', listing: true } } });

http.start();

A function path can be used to serve different directory trees based on the incoming request. For example:

// Create Hapi server
var http = new Hapi.Server('0.0.0.0', 8080);

var directoryPath = function (request) {

    if (isMobileDevice(request)) {
        return './mobile';
    }

    return './public';
};

http.addRoute({ method: 'GET', path: '/{path*}', handler: { directory: { path: directoryPath } } });

http.start();

View

Views provide a better way of generating HTML than string and variable concatenation. Similar to other web servers, hapi views allow handlers to efficiently generate HTML using templates by executing an individual template with a pre-generated context object (which may contain dynamic content).

The following example shows how to render a basic handlebars/mustache template:

index.js

    
    var http = new Hapi.Server('0.0.0.0', 8080, {
        views: {
            path: __dirname + '/templates'
        }
    });
        
    var handler = function (request) {

        request.reply.view('index', {
            title: 'Views Example',
            message: 'Hello, World'
        }).send();
    };

    http.addRoute({ method: 'GET', path: '/', handler: handler });
    http.start();

An example template:

templates/index.html

<!DOCTYPE html>
<html>
    <head>
        <title>{{title}}</title>
    </head>
    <body>
        <div>
            <h1>{{message}}</h1>
        </div>
    </body>
</html>

On request, the user would be shown:

<!DOCTYPE html>
<html>
    <head>
        <title>Views Example</title>
    </head>
    <body>
        <div>
            <h1>Hello, World</h1>
        </div>
    </body>
</html>

The Hapi.Server settings may also be overridden on a per view basis without affecting others:

request.render.view(tmpl, ctx, { path: '/a/different/path' });

Full working examples covering features such as layouts and partials can be found in the examples/views/handlebars folder.

Views Handler

The route handler can be set to an object that points to a view file in order to make it easy to render a simple view. The view context will have the payload, params, or querystring data that are available with the request. For example, to render an 'about' page a route can be added as follows:

    var http = new Hapi.Server('0.0.0.0', 8080, {
        views: {
            path: __dirname + '/templates'
        }
    });

    http.addRoute({ method: 'GET', path: '/{user}/about', handler: { view: 'about });
    http.start();

Then in the view there are properties for params, payload, and querystring. Below is an example of rendering the 'user' that is passed in from the request path along with related values from the querystring.

<!DOCTYPE html>
<html>
    <head>
        <title>About {{ params.user }}</title>
    </head>
    <body>
        <div>
            <h1>About {{ params.user }}</h1>
            <div>
                Age: {{ querystring.age }}
            </div>
            <div>
                Interests: {{ querystring.interests }}
            </div>
        </div>
    </body>
</html>

Layouts

The View system supports Layouts. Layouts are a single template file which is used as a parent template for individual view templates - the view template is directly embedded in a layout. This allows developers to give the website(s) a consistent appearance while also keeping HTML code as well as minimizing repeated code (the boilerplate with stylesheet includes, javascript includes, html displayed on every page).

To use, set the Hapi view option layout to true and create a file layout.html in your views.path.

layout.js

    var options = {
        views: {
            path: __dirname + '/templates',
            engine: {
                module: 'handlebars',
                extension: 'html'
            },
            layout: true
        }
    };
    
    var handler = function (request) {

        request.reply.view('withLayout/index', {
            title: 'examples/views/layout.js | Hapi ' + Hapi.utils.version(),
            message: 'Hello World!\n'
        }).send();
    };

    var server = new Hapi.Server(8080, options);
    server.addRoute({ method: 'GET', path: '/', handler: handler });
    server.start();

templates/layout.html

<!DOCTYPE html>
<html>
    <head>
        <title>{{title}}</title>
    </head>
    <body>
        <p>Layout header</p>
        {{{ content }}}
        <p>Layout footer</p>
    </body>
</html>

templates/withLayout/index.html

<div>
    <h1>{{message}}</h1>
</div>

returned to user:

<!DOCTYPE html>
<html>
    <head>
        <title>examples/views/layout.js | Hapi 0.11.1</title>
    </head>
    <body>
        <p>Layout header</p>
        <div>
            <h1>Hello World!\n</h1>
        </div>
        <p>Layout footer</p>
    </body>
</html>

The layout.html must be located in the path or an error will be returned. Notice that the content from view template withLayout/index is executed with the context provided in the handler then embedded into the layout in place of {{{ content }}}. To change the keyword for embedding the view template, set the layoutKeyword option.

Partials

The View system also supports Partials. Partials are small segments of template code that can be nested and reused throughout other templates.

partials.js

    var options = {
        views: {
            path: __dirname + '/templates',
            engine: {
                module: 'handlebars'
            },
            partials: {
                path: __dirname + '/templates/withPartials'
            }
        }
    };
    
    var handler = function (request) {

        request.reply.view('withPartials/index', {
            title: 'examples/views/partials.js | Hapi ' + Hapi.utils.version(),
            message: 'Hello World!\n'
        }).send();
    };

    var server = new Hapi.Server(3000, options);
    server.addRoute({ method: 'GET', path: '/', handler: handler });
    server.start();

withPartials/index.html

<!DOCTYPE html>
<html>
    <head>
        <title>{{title}}</title>
    </head>
    <body>
        {{> header}}
        <div>
            <h1>{{message}}</h1>
        </div>
        {{> footer}}
    </body>
</html>

withPartials/header.html

<div>
    <h3>Views with Partials</h3>
</div>

withPartials/footer.html

<footer>
    <p>hapi.js 2013</p>
</footer>

returned to user

<!DOCTYPE html>
<html>
    <head>
        <title>examples/views/partials.js | Hapi 0.11.1</title>
    </head>
    <body>
        <div>
            <h3>Views with Partials</h3>
        </div>
        <div>
            <h1>Hello World!\n</h1>
        </div>
        <footer>
            <p>hapi.js 2013</p>
        </footer>
    </body>
</html>

The above example will use views.partials.path as the partials directory. Hapi will recursively find template files and automatically add them to the partial registry for use in view templates.

Deeply nested partials are also supported. A view template can reference a partial stored in viewsPath/nav/nav.html like so:

    <body>
        {{> nav/nav}}
        <div id="container">
    ...

Multiple Engines

Multiple engine support is functional for most templating systems (particularly those that employ a .compile function). Thus, multiple templating systems may be used in a single Hapi instance. Custom options may be passed to each .view function to customize compile options on a per endpoint basis - the functions behave as they would on a single-engine setup.

Hapi distinguishes between the engines by checking which file extension has been configured by a particular templating engine.

var ctx = {
    title: 'examples/views/mixed/basic.js | Hapi ' + Hapi.utils.version(),
    message: 'Hello World!'
}

var oneHandler = function (request) {
    
    request.reply.view('index', ctx).send();
};

var twoHandler = function (request) {
    
    request.reply.view('handlebars', ctx).send();
};

var options = {
    views: {
        path: __dirname + '/templates',
        engines: {
            'html': { module: 'handlebars' },
            'jade': { module: 'jade' }
        }
    }
};

var server = new Hapi.Server(3000, options);
server.addRoute({ method: 'GET', path: '/one', handler: oneHandler });
server.addRoute({ method: 'GET', path: '/two', handler: twoHandler });
server.start();

Documentation

This is an experimental feature and is likely to change!

In order to make it easy to generate documentation for the routes you add to hapi, a documentation generator is provided. By default the documentation generator is turned off. To enable the docs endpoint add a new route with a handler object that has a docs property set to true or to an object with the following options:

• indexTemplatePath - the file path where the index template file is located. Default is 'lib/templates/index.html' inside the lout module.
• indexTemplate - the raw source of a index template to use. If indexTemplate is provided then it will be used over the file located at indexTemplatePath.
• routeTemplatePath - the file path where the routes template file is located. Default is 'lib/templates/route.html' inside the lout module.
• routeTemplate - the raw source of a route template to use. If routeTemplate is provided then it will be used over the file located at routeTemplatePath.
• templateParams - an optional object of any extra information you want to pass into your template, this will be located in the templateParams object in the template data object.

By default there is an index page that lists all of the available routes configured in hapi that is located at the docsEndpoint. From this page users are able to navigate to individual routes to read the related documentation.

The simplest example of enabling docs on a site is shown in the following example:

// Create Hapi server
var http = new Hapi.Server('0.0.0.0', 8080);

http.addRoute({ method: 'GET', path: '/docs', handler: { docs: true } });

http.start();

Request Logging

In addition to the General Events Logging mechanism provided to log non-request-specific events, hapi provides a logging interface for individual requests. By associating log events with the request responsible for them, it is easier to debug and understand the server's behavior. It also enables batching all the request log events and deliver them to the monitor as a single package.

The request object is also decorated with the following methods.

• 'log(tags, [data, timestamp])' which adds a record to the request log where:
  • 'tags' - a single string or an array of strings (e.g. ['error', 'database', 'read']) used to identify the logged event. Tags are used instead of log levels and provide a much more expressive mechanism for describing and filtering events.
  • 'data' - an optional message string or object with the application data being logged.
  • 'timestamp' - an optional timestamp override (if not present, the server will use current time), expressed in milliseconds since 1970 (new Date().getTime()).
• 'getLog(tags)' - Returns an array of events which match the tag(s) specifed.

For example:

var Hapi = require('hapi');

// Create Hapi servers
var http = new Hapi.Server('0.0.0.0', 8080);

// Route handler
var testLogs = function (request) {

    request.log('error', new Error('Something failed'));
    
    if (request.getLog('error').length === 0) {
        request.reply('Success!');
    }
    else {
        request.reply('Failure!');
    }
};

// Set routes
http.addRoute({ method: 'GET', path: '/', handler: testLogs });

// Start Hapi servers
http.start();

The 'request.log' method is always available.

Not Found Handler

Whenever a route needs to respond with a simple 404 message use the 'notFound' handler. This can be done by simply setting the route 'handler' property to the string 'notFound'. Below is an example of a route that responds with a 404.

{ method: 'GET', path: '/hideme', handler: 'notFound' }

Route Authentication

To override the default authentication settings for a route use the 'auth' object on a routes configuration. Below are the available options for the 'auth' configuration on a route.

• mode - determines if a route requires authentication. Options are none, optional, and required (defaults to required when the server has authentication configured and none when it doesn't).
• strategy - the authentication strategy to use, will use the default strategy if not set.
• strategies - an array in priority order of what authentication strategies the route supports.
• scope - required session scope in order to access the endpoint.
• tos - number that represents terms of service. Session must have an ext equal or greater than the configured tos value.
• entity - the type of object that must exist on the session. Options are any, user, and app.

When multiple authentication strategies are configured on the server individual routes can specify which of those strategies to use in priority order. Below is an example showing how to create a route that supports the 'hawk' and 'basic' strategies and where authentication is optional.

{ method: 'GET', path: '/', handler: handler, config: { auth: { strategies: ['hawk', 'basic'], mode: 'optional' } } }

If a route doesn't specify the strategy or strategies to use then the servers 'default' strategy will be used. When a single strategy is configured on the server then it will be given the strategy name 'default' and will be used by any route that supports authentication.

Query Validation

When a request URI includes a query component (the key-value part of the URI between ? and #), the query is parsed into its individual key-value pairs (see Query String) and stored in 'request.query'.

The route config.validate.query defines the query validation rules performed before the route handler is invoked. Supported values:

• 'true' or '{}' - any query parameters allowed (no validation performed). This is the default.
• 'false' - no query parameters allowed.
• a validation rules object as described in Data Validation.

Payload Validation

The route config.validate.schema defines the payload validation rules performed before the route handler is invoked. Supported values:

• 'true' or '{}' - any payload allowed (no validation performed). This is the default.
• 'false' - no payload allowed.
• a validation rules object as described in Data Validation.

Path Validation

When a request comes in for a route that allows for path parameters the request is path parameters are parsed into request.params.

The route config.validate.path defines the path validation rules performed before the route handler is invoked. Supported values:

• 'true' or '{}' - any path parameters allowed (no validation performed). This is the default.
• 'false' - no path variables allowed.
• a validation rules object as described in Data Validation.

Response Validation

The route config.response defines the payload validation rules performed after the route handler is invoked. Supported values:

• 'null' - any payload allowed (no validation performed). This is the default.
• 'false' or '{}' - no payload allowed.
• an object with the following options
  • 'schema' - a validation rules object as described in Data Validation.
  • 'sample' - the percentage of responses to validate. By default 100% of responses will be validated, to turn this off set the value to 0. To validate half of the responses set this value to 50.
  • 'failAction' - 'error' (return 500), 'log' (report error but send reply as-is), or 'ignore' (send reply as-is) when a response is invalid. Defaults to 'error'.

Response validation can only be performed on object responses and will otherwise result in an error.

Caching

'GET' routes may be configured to use the built-in cache if enabled using the server cache option. The route cache config has the following options:

• mode - determines if the route is cached on the server, client, or both. Defaults to 'server+client'.
  • server+client - Caches the route response on the server and client (default)
  • client - Sends the Cache-Control HTTP header on the response to support client caching
  • server - Caches the route on the server only
  • none - Disable cache for the route on both the client and server
• segment - Optional segment name, used to isolate cached items within the cache partition. Defaults to '#name' for server helpers and the path fingerprint (the route path with parameters represented by a '?' character) for routes. Note that when using the MongoDB cache strategy, some paths will require manual override as their name will conflict with MongoDB collection naming rules.
• expiresIn - relative expiration expressed in the number of milliseconds since the item was saved in the cache. Cannot be used together with expiresAt.
• expiresAt - time of day expressed in 24h notation using the 'MM:HH' format, at which point all cache records for the route expire. Cannot be used together with expiresIn.
• strict - determines if only 'Cacheable' responses are allowed. If a response that is not 'Cacheable' is returned and strict mode is enabled then an error will be thrown. Defaults to 'false'.

For example, to configure a route to be cached on the client and to expire after 2 minutes the configuration would look like the following:

{
    mode: 'client',
    expiresIn: 120000
}

The server-side cache also supports these advanced options:

• staleIn - number of milliseconds from the time the item was saved in the cache after which it is considered stale. Value must be less than 86400000 milliseconds (one day) if using expiresAt or less than the value of expiresIn. Used together with staleTimeout.
• staleTimeout - if a cached response is stale (but not expired), the route will call the handler to generate a new response and will wait this number of milliseconds before giving up and using the stale response. When the handler finally completes, the cache is updated with the more recent update. Value must be less than expiresIn if used (after adjustment for units).

Prerequisites

Before the handler is called, it is often necessary to perform other actions such as loading required reference data from a database. The pre option allows defining such pre-handler methods. The methods are called in order, unless a mode is specified with value 'parallel' in which case, all the parallel methods are executed first, then the rest in order. The pre is a mixed array of functions and objects. If a function is included, it is the same as including an object with a single method key. The object options are:

• method - the function to call. The function signature is 'function (request, next)'. 'next([result])' must be called when the operation concludes. If the result is an Error, execution of other prerequisites stops and the error is handled in the same way as when an error is returned from the route handler. The method can be a string invoking a server helper.
• assign - key name to assign the result of the function to within 'request.pre'.
• mode - set the calling order of the function to 'serial' or 'parallel'. Defaults to 'serial'.

For example:

// Create Hapi servers
var http = new Hapi.Server('0.0.0.0', 8080);

var fetch1 = function (request, next) {

    next('Hello');
};

var fetch2 = function (request, next) {

    next('World');
};

var fetch3 = function (request, next) {

    next(request.pre.m1 + ' ' + request.pre.m2);
};

var get = function (request) {

    request.reply(request.pre.m3 + '\n');
};

// Set routes
http.addRoute({
    method: 'GET',
    path: '/',
    config: {
        pre: [
            { method: fetch1, assign: 'm1', mode: 'parallel' },
            { method: fetch2, assign: 'm2', mode: 'parallel' },
            { method: fetch3, assign: 'm3' },
        ],
        handler: get
    }
});

// Start Hapi servers
http.start();

Data Validation

hapi supports a rich set of data types and validation rules which are described in detail in the joi module documentation. For example:

var Hapi = require('hapi');

var S = Hapi.Types.String;
var I = Hapi.Types.Int;

var rules = {
    username: S().required().alphanum().min(3).max(30).with('email'),
    password: S().regex(/[a-zA-Z0-9]{3,30}/).without('token'),
    token: S(),
    birthyear: I().min(1850).max(2012),
    email: S().email(),
    type: S().valid('admin', 'limited', 'normal')
};

In which:

• 'username' is a required alphanumeric string, 3 to 30 characters long, and must appear together with 'email'.
• 'password' is an optional string matching a regular expression, and must not appear together with 'token'.
• 'token' is an optional string.
• 'birthyear' is an optional integer between 1980 and 2012.
• 'email' is an optional string with valid email address.
• 'type' is an optional string which must be set to one of three available values.

Response Errors

The 'Hapi.Error' module provides helper methods to generate error responses:

• 'badRequest([message])' - HTTP 400 (Bad Request).
• 'unauthorized([message])' - HTTP 401 (Unauthorized).
• 'forbidden([message])' - HTTP 403 (Not Allowed).
• 'notFound([message])' - HTTP 404 (Not Found).
• 'internal([message, data])' - HTTP 500 (Internal Error). The optional message and data values are not returned to the client but are logged internally.

The message value is optional and will be returned to the client in the response unless noted otherwise. For example:

function onUnknownRoute(request) {

    request.reply(Hapi.Error.unknown('Sorry, nobody home'));
}

Error responses are send as JSON payload with the following keys (unless an error response override is configured):

• code - the HTTP status code (e.g. 400).
• error - the HTTP status message (e.g. 'Bad Request').
• message - the returned message if provided.

The complete error repsonse including any additional data is added to the request log.

State Management

Raw Cookies

Cookies can be set directly via the response 'state(name, value, options)' interface where:

• 'name' - is the cookie name,
• 'value' - is the cookie value, and
• 'options' - is an optional structure with the following optional keys:
  • `ttl' - time-to-live in milliseconds.
  • isSecure - sets the 'Secure' flag.
  • isHttpOnly - sets the 'HttpOnly' flag.
  • path - the path scope.
  • domain - the domain scope.
  • encoding - encoding performs on the provided value before serialization. Options are:
    • 'none' - no encoding. This is the default value. Value must be a string.
    • 'base64' - string value is encoded using Base64.
    • 'base64json' - object value is JSON-stringified than encoded using Base64.
    • 'form' - object value is encoded using the x-www-form-urlencoded method.

Cookie definitions can be registered with the server using the server's 'addState(name, options)' method, where 'options' is the same as above. If a cookie definition is found, the options are used for that cookie as defaults before other options specified at the time of state() invocation are applied. In addition, the encoding option is used when receiving a cookie from the client to parse the cookie's value.

General Events Logging

Most of the server's events usually relate to a specific incoming request. However, there are sometimes event that do not have a specific request context. hapi provides a logging mechanism for general events using a singleton logger 'Hapi.Log' module. The logger provides the following methods:

• 'event(tags, [data, timestamp])' - generates an event where:
  • 'tags' - a single string or an array of strings (e.g. ['error', 'database', 'read']) used to identify the event. Tags are used instead of log levels and provide a much more expressive mechanism for describing and filtering events.
  • 'data' - an optional message string or object with the application data being logged.
  • 'timestamp' - an optional timestamp override (if not present, the server will use current time), expressed in milliseconds since 1970 (new Date().getTime()).
• 'print(event)' - outputs the given 'event' to the console.

The logger is an event emitter. When an event is generated, the logger's 'log' event is emitted with the event object as value. If no listeners are registered, the event is printed to the console.

For example:

var Hapi = require('hapi');

// Listen to log events
Hapi.Log.on('log', function (event) {

    // Send to console
    Hapi.Log.print(event);
});

// Generate event
Hapi.Log.event(['test','info'], 'Test event');

Request Tails

It is often desirable to return a response as quickly as possible and perform additional (slower) actions afterwards (or in parallel). These actions are called request tails. For example, a request may trigger a database update tail that should not delay letting the client know the request has been received and will be processed shortly. However, it is still desirable to associate the tails with the request and to know when every single request related action has completed (in other words, when the request stopped wagging).

hapi provides a simple facility for keeping track of pending tails by providing the following request methods:

• 'addTail([name])' - registers a named tail and returns a tail function. The tail function must be retained and used to remove the tail when completed. The method is available on every event or extension hook prior to the 'tail' event.
• 'removeTail(tail)' - removes a tail to notify the server that the associated action has been completed.

Alternatively, the returned tail function can be called directly without using the removeTail() method.

For example:

var Hapi = require('hapi');

// Create Hapi servers
var http = new Hapi.Server('0.0.0.0', 8080);

// Route handler
var get = function (request) {

    var tail1 = request.addTail('tail1');
    setTimeout(function () {

        request.removeTail(tail1);              // Using removeTail() interface
    }, 5000);

    var tail2 = request.addTail('tail2');
    setTimeout(function () {

        tail2();                                // Using tail function interface
    }, 2000);

    request.reply('Success!');
};

// Set routes
http.addRoute({ method: 'GET', path: '/', handler: get });

// Listen to tail events
http.on('tail', function (request) {

    console.log('Wag the dog');
});

// Start Hapi servers
http.start();

Request Injection

Request injection is the process of simulating an HTTP request without making an actual socket request. Injection is useful for testing or debugging purposes, but also for invoking routing logic internally without the overhead or limitations of the network stack. For example, implementing a batch mechanism which calls multiple internal routes.

hapi uses the shot module for performing injections. To inject a request, use the server's 'inject(options, callback)' method in which:

• 'options' - is an object containing the request information. Available options:
  • method - the request HTTP method. Required.
  • url - the request URL (as it would appear in an incoming node request object). Required.
  • headers - any request headers. Optional.
  • payload - a string or Buffer containing the request payload. Optional.
  • session - a session object containing authentication information as described in Route Handler. The session option is used to bypass the default authentication validation and use a pre-authenticated session. Optional.
• 'callback' - a callback function with the signature 'function (res)' where 'res' is the injection response object. The response object properties include:
  • 'headers' - an array containing the headers set.
  • 'statusCode' - the HTTP status code.
  • 'readPayload()' - the payload converted to a string.
  • 'result' - if present, the original route handler reply object.
  • 'raw' - the injection request and response objects.

This is an experimental feature and is likely to change!

For example:

// Create Hapi server
var http = new Hapi.Server('0.0.0.0', 8080);

// Handler
var get = function (request) {

    request.reply('Success!');
};

// Set routes
http.addRoute({ method: 'GET', path: '/', handler: get });

// Injection options
var req = {
    method: 'get',
    url: '/'
};

http.inject(req, function (res) {

    console.log(res.result || res.readPayload());
});

Server Helpers

Server helpers are functions registered with the server and can be used throughout the application. The advantage of using helpers is that they can be configured to use the built-in cache and shared across multiple request handlers. This provides a useful method for speeding up performance by declaring functions as common utilities with a shared cache.

The signature of helper functions is 'function (arg1, arg2, ..., arg3, next)' where next is a function defined as 'function (result)'. 'result' can be any value or an Error (which must be generated using the hapi Error module is the helper is used as a prerequisite method).

To add a helper, use the server's 'addHelper(name, method, options)' method where:

• 'name' - is a unique helper name used to call the method (e.g. 'server.helpers.name').
• 'method' - is the helper function.
• 'options' - optional settings where:
  • cache - cache configuration as described in Caching. mode can use the default or be set to 'server'.
  • keyGenerator - the server will automatically generate a unique key if the function's arguments (with the exception of the last 'next' argument) are all of type string, number, or boolean. However if the function uses other types of arguments, a key generation function must be provided which takes the same arguments as the function and returns a unique string (or null if no key can be generated). Note that when the keyGenerator method is invoked, the arguments list will include the next argument which must not be used in calculation of the key.

For example:

// Create Hapi server
var server = new Hapi.Server('0.0.0.0', 8080);

var user = function (id, next) {

    next({ id: id });
};

var options = {
    cache: {
        expiresIn: 2000,
        staleIn: 1000,
        staleTimeout: 100
    },
    keyGenerator: function (id) {

        return id;
    };
};

server.addHelper('user', user, options);

server.helpers.user(4, function (result) {

    console.log(result);
});

Or used as a prerequisites, by passing a string with the helper invocation using the helper name and passing parameters that are all members of the request object (without next):

http.addRoute({
    method: 'GET',
    path: '/user/{id}',
    config: {
        pre: [
            'user(params.id)'
        ],
        handler: function (request) {

            request.reply(request.pre.user);
        }
    }
});

The End

hapi hapi, joi joi