π Convert static OpenAPI schemas to TypeScript types quickly using pure Node.js. Fast, lightweight, (almost) dependency-free, and no Java/node-gyp/running OpenAPI servers necessary.
Features
- β Supports YAML and JSON formats
- β Supports advanced OpenAPI 3.1 features like discriminators
- β
Supports loading via remote URL (simple authentication supported with the
--authflag) - β
Supports remote references:
$ref: "external.yaml#components/schemas/User" - β Fetches remote schemas quickly using undici
Examples
π See examples
Note:οΈ openapiTS requires VALID OpenAPI 3.x schemas to work, and this library does not handle validation. There are several quality tools that handle this like @apidevtools/swagger-parser. Make sure to validate your schemas first!
npx openapi-typescript schema.yaml --output schema.ts
# π Loading spec from schema.yamlβ¦
# π schema.yaml -> schema.ts [250ms]npx openapi-typescript "specs/**/*.yaml" --output schemas/
# π Loading spec from specs/one.yamlβ¦
# π Loading spec from specs/two.yamlβ¦
# π Loading spec from specs/three.yamlβ¦
# π specs/one.yaml -> schemas/specs/one.ts [250ms]
# π specs/two.yaml -> schemas/specs/two.ts [250ms]
# π specs/three.yaml -> schemas/specs/three.ts [250ms]Thanks, @sharmarajdaksh!
npx openapi-typescript https://petstore3.swagger.io/api/v3/openapi.yaml --output petstore.d.ts
# π Loading spec from https://petstore3.swagger.io/api/v3/openapi.yamlβ¦
# π https://petstore3.swagger.io/api/v3/openapi.yaml -> petstore.d.ts [650ms]Thanks, @psmyrdek!
Import any top-level item from the generated spec to use it. It works best if you also alias types to save on typing:
import { components } from "./generated-schema.ts";
type APIResponse = components["schemas"]["APIResponse"];Because OpenAPI schemas may have invalid TypeScript characters as names, the square brackets are a safe way to access every property.
Operations can be imported directly by their operationId:
import { operations } from "./generated-schema.ts";
type getUsersById = operations["getUsersById"];Thanks, @gr2m!
Any fetch call can be typed from the paths like so:
import { paths } from './my-types';
const response: paths["/api/v1/user/{user_id}"]["get"][200 | 500] = await fetch(`/api/v1/user/${user_id}`).then((res) => res.json());Or if you add the --path-params-as-types CLI flag, you can take advantage of more automatic inference:
import { paths } from './my-types';
const url = `/api/v1/user/${user_id}`;
const response: paths[url]["get"][200 | 500] = await fetch(url).then((res) => res.json());You can generate a fully-typed Fetch API client from openapiTS types with the openapi-typescript-fetch package:
import { paths } from "./petstore";
import { Fetcher } from "openapi-typescript-fetch";
const fetcher = Fetcher.for<paths>();
// GET
const findPetsByStatus = fetcher.path("/pet/findByStatus").method("get").create();
const { status, data: pets } = await findPetsByStatus({
status: ["available", "pending"],
});
// POST
const addPet = fetcher.path("/pet").method("post").create();
await addPet({ ... })Thanks, @ajaishankar!
The following flags can be appended to the CLI command.
| Option | Alias | Default | Description |
|---|---|---|---|
--help |
Display inline help message and exit | ||
--version |
Display this libraryβs version and exit | ||
--output [location] |
-o |
(stdout) | Where should the output file be saved? |
--auth [token] |
Provide an auth token to be passed along in the request (only if accessing a private schema) | ||
--header |
-x |
Provide an array of or singular headers as an alternative to a JSON object. Each header must follow the key: value pattern |
|
--headers-object="{β¦}" |
-h |
Provide a JSON object as string of HTTP headers for remote schema request. This will take priority over --header |
|
--http-method |
-m |
GET |
Provide the HTTP Verb/Method for fetching a schema from a remote URL |
--immutable-types |
false |
Generates immutable types (readonly properties and readonly array) | |
--additional-properties |
false |
Allow arbitrary properties for all schema objects without additionalProperties: false |
|
--default-non-nullable |
false |
Treat schema objects with default values as non-nullable | |
--export-type |
-t |
false |
Export type instead of interface |
--path-params-as-types |
false |
Allow dynamic string lookups on the paths object |
|
--support-array-length |
false |
Generate tuples using array minItems / maxItems |
|
--alphabetize |
false |
Sort types alphabetically |
By default, your URLs are preserved exactly as-written in your schema:
export interface paths {
'/user/{user_id}': components["schemas"]["User"];
}Which means your type lookups also have to match the exact URL:
import { paths } from './my-schema';
const url = `/user/${id}`;
type UserResponses = paths['/user/{user_id}']['responses'];But when --path-params-as-types is enabled, you can take advantage of dynamic lookups like so:
import { paths } from './my-schema';
const url = `/user/${id}`;
type UserResponses = paths[url]['responses']; // automatically matches `paths['/user/{user_id}']`Though this is a contrived example, you could use this feature to automatically infer typing based on the URL in a fetch client or in some other useful place in your application.
Thanks, @Powell-v2!
This option is useful for generating tuples if an array type specifies minItems or maxItems.
For example, given the following schema:
components:
schemas:
TupleType
type: array
items:
type: string
minItems: 1
maxItems: 2Enabling --support-array-length would change the typing like so:
export interface components {
schemas: {
- TupleType: string[];
+ TupleType: [string] | [string, string];
};
}This results in more explicit typechecking of array lengths.
Note: this has a reasonable limit, so for example maxItems: 100 would simply flatten back down to string[];
Thanks, @kgtkr!
npm i --save-dev openapi-typescriptimport fs from "node:fs";
import openapiTS from "openapi-typescript";
// example 1: load [object] as schema (JSON only)
const schema = await fs.promises.readFile("spec.json", "utf8") // must be OpenAPI JSON
const output = await openapiTS(JSON.parse(schema));
// example 2: load [string] as local file (YAML or JSON; released in v4.0)
const localPath = new URL("./spec.yaml", import.meta.url); // may be YAML or JSON format
const output = await openapiTS(localPath);
// example 3: load [string] as remote URL (YAML or JSON; released in v4.0)
const output = await openapiTS("https://myurl.com/v1/openapi.yaml");The Node API may be useful if dealing with dynamically-created schemas, or youβre using within context of a larger application. Pass in either a JSON-friendly object to load a schema from memory, or a string to load a schema from a local file or remote URL (it will load the file quickly using built-in Node methods). Note that a YAML string isnβt supported in the Node.js API; either use the CLI or convert to JSON using js-yaml first.
The Node API supports all the CLI flags above in camelCase format, plus the following additional options:
| Name | Type | Default | Description |
|---|---|---|---|
commentHeader |
string |
Override the default βThis file was auto-generated β¦β file heading | |
inject |
string |
Inject arbitrary TypeScript types into the start of the file | |
transform |
Function |
Override the default Schema Object β TypeScript transformer in certain scenarios | |
postTransform |
Function |
Same as transform but runs after the TypeScript transformation |
If using the Node.js API, you can override the normal Schema Object transformer with your own. This is useful for providing enhanced functionality for specific parts of your schema.
For example, say your schema has the following property:
properties:
updated_at:
type: string
format: date-timeBy default, openapiTS will generate updated_at?: string; because itβs not sure which format you want by "date-time" (formats are nonstandard and can be whatever youβd like). But we can enhance this by providing our own custom formatter, like so:
const types = openapiTS(mySchema, {
transform(schemaObject, metadata): string {
if ("format" in schemaObject && schemaObject.format === "date-time") {
return "Date";
}
},
});That would result in the following change:
- updated_at?: string;
+ updated_at?: Date;Any Schema Object present in your schema will be run through this formatter (even remote ones!). Also be sure to check the metadata parameter for additional context that may be helpful.
There are many other uses for this besides checking format. Because this must return a string you can produce any arbitrary TypeScript code youβd like (even your own custom types).
β¨ Donβt forget about postTransform() as well! It works the same way, but runs after the TypeScript transformation so you can extend/modify types as-needed.
- Support converting any valid OpenAPI schema to TypeScript types, no matter how complicated.
- This library does NOT validate your schema, there are other libraries for that.
- The generated TypeScript types must match your schema as closely as possible (e.g. no renaming to
PascalCase) - This library should never require Java, node-gyp, or some other complex environment to work. This should require Node.js and nothing else.
- This library will never require a running OpenAPI server to work.
PRs are welcome! Please see our CONTRIBUTING.md guide.
Thanks goes to these wonderful people (emoji key):
This project follows the all-contributors specification. Contributions of any kind welcome!