Igor-Palaguta / SwifQL

💎 A Swift DSL for type-safe, extensible, and transformable SQL queries.

This lib can work either stand alone, or with Vapor3.

For now it supports PostgreSQL and MySQL. But it's not so hard to add other dialects 🙂

Please feel free to ask any questions in issues, and also you could find me in the Discord app as @iMike#3049 or even better just join #swifql channel on Vapor's Discord server 🙂

NOTE:

If you haven't found some functions available out-of-the-box then please check files like SwifQLable+Select and others in Sources/SwifQL folder to ensure how easy it is to extend SwifQL to support anything you need 🚀

And feel free to send pull requests with your awesome new extensions ❤️

Support SwifQL development by giving a ⭐️

Installation

.package(url: "https://github.com/MihaelIsaev/SwifQL.git", from:"0.20.1")

Stand alone

In your target's dependencies add "SwifQL" and "SwifQLPure", e.g. like this:

.target(name: "App", dependencies: ["SwifQL", "SwifQLPure"]),

With vapor 3

In your target's dependencies add "SwifQL" and "SwifQLVapor", e.g. like this:

.target(name: "App", dependencies: ["Vapor", "SwifQL", "SwifQLVapor"]),

Philosophy

This lib provides you with ability to build an SQL query from a little tiny pieces of it.

For example if you'd like to execute

SELECT * FROM "User" WHERE "email" = '[e-mail]'

then with SwifQL you can build it like this

SwifQL.select(User.table.*).from(User.table).where(\User.email == "[e-mail]")

How it works under the hood

SwifQL object needed just to start writing query, but it's just an empty object that conforms to SwifQLable.

You can build your query with everything which conforms to SwifQLable, because SwifQLable is that very piece which will be used for concatenation to build a query.

If you take a look at the lib's files you may realize that the most of files are just extensions to SwifQLable.

All available operators like select, from, where, and orderBy realized just as a function in SwifQLable extension and these functions always returns SwifQLable as a result. That's why you can write a query by calling SwifQL.select().from().where().orderBy() one by one. That's awesome cause it feels like writing a raw SQL, but it also gives you an ordering limitation, so if you write SwifQL.select().where().from() then you'll get wrong query as a result. But this limitation is resolved by using special builders, like SwifQLSelectBuilder (read about it later below).

So let's take a look how lib builds a simple SELECT "User".* FROM "User" WHERE "User"."email" = '[e-mail]' query

First of all we should split query into the parts. Almost every word and punctuation here is a SwifQLable piece.

• SELECT is Fn.Operator.select
• is Fn.Operator.space
• "User" is User.table
• .* is postfix operator .*
• is Fn.Operator.space
• FROM is Fn.Operator.from
• "User" is User.table
• is Fn.Operator.space
• WHERE is Fn.Operator.where
• is Fn.Operator.space
• "User"."email" is \User.email keypath
• is Fn.Operator.space
• == is infix operator ==
• is Fn.Operator.space
• '[e-mail]' is SwifQLPartUnsafeValue (it means that this value should be passed as $1 to the database)

That's crazy, but awesome, right? 😄 But it's under the hood, so no worries! 😃 I just wanted to explain, that if you need something more than already provided then you'll be able to add needed operators/functions easily just by writing little extensions.

And also there is no overhead, it works pretty fast, but I'd love to hear if you know how to make it faster.

This way gives you almost absolute flexibility in building queries. More than that as lib support SQLDialect's it will build this query different way for PostgreSQL and MySQL, e.g.:

• PostgreSQL: SELECT "User".* FROM "User" WHERE "User"."email" = '[e-mail]'
• MySQL: SELECT User.* FROM User WHERE User.email = '[e-mail]'

Usage

Preparation

Your database models should be conformed to Tableable protocol.

extension YourModel: Tableable {}

With Vapor

import SwifQLVapor and import SwifQL together cause Swift won't export predicates from SwifQL through SwifQLVapor, unfortunately.

With pure Swift or other frameworks

import SwifQLPure and import SwifQL together cause Swift won't export predicates from SwifQL through SwifQLPure, unfortunately.

How to build query

Instead of writing Model.self you should write Model.table, cause without Vapor you should conform your models to Table, and with Vapor its Models are already conforms to Table.

let query = SwifQL.select(\User.email, \User.name, \User.role)
                  .from(User.table)
                  .orderBy(.asc(\User.name))
                  .limit(10)

How to get raw query string (common case for pure Swift usage)

You can either get unsafe raw SQL string

let rawSQLString = query.prepare(.psql).plain

or get splitted object into formatted raw SQL string with $ symbols and separated array of unsafe values

let splittedQuery = query.prepare(.psql).splitted
let formattedSQLQuery = splittedQuery.query // formatted raw SQL string with $ symbols instead of values
let values = splittedQuery.values // an array of [Encodable] values

Then just put it into your database driver somehow 🙂

How to execute and decode it with Vapor's PostgreSQL or MySQL drivers

In case if you have a Container like req: Request or app: Application

query.execute(on: req, as: .psql) //for PostgreSQL
query.execute(on: req, as: .mysql) //for MySQL

In case if you want to execute it directly on SQLConnection

query.execute(on: connection)

Anyway it will return you a Future<SQLRawBuilder> which can be easily used for results decoding.

Decoding

Vapor's SQLRawBuilder provides you with ability to decode all queried rows or only a first one

query.execute(on: connection).all(decoding: User.self) // returns Future<[User]>
query.execute(on: connection).first(decoding: User.self) // returns Future<User?>
query.execute(on: connection).first(decoding: User.self).unwrap(or: Abort(.notFound)) // throws or returns Future<User>

So, let's write a full simple example for querying current User model, e.g. for PostgreSQL:

func oneUser(_ req: Request) throws -> Future<User> {
    let user: User = try req.requireAuthenticated()
    return try SwifQL.select(\User.email, \User.name, \User.role)
                     .from(User.table)
                     .where(\User.id == user.requireID())
                     .execute(on: req, as: .psql)
                     .first(decoding: User.self)
                     .unwrap(or: Abort(.notFound, reason: "User not found"))
}

I believe that it looks good 😊

Insert Into

Single record

SQL example

INSERT INTO "User" ("email", "name") VALUES ('[e-mail]', 'John Doe'), ('[e-mail]', 'Samuel Jackson')

SwifQL representation

SwifQL.insertInto(User.table, fields: \User.email, \User.name).values("[e-mail]", "John Doe")

Batch

SQL example

INSERT INTO "User" ("email", "name") VALUES ('[e-mail]', 'John Doe'), ('[e-mail]', 'Samuel Jackson')

SwifQL representation

SwifQL.insertInto(User.table, fields: \User.email, \User.name).values(array: ["[e-mail]", "John Doe"], ["[e-mail]", "Samuel Jackson"])

Builders

For now I implemented only one builder

Select builder

SwifQLSelectBuilder - by using it you could easily build a select query but in multiple lines without carying about ordering.

let builder = SwifQLSelectBuilder()
builder.where(\User.id == 1)
builder.from(User.table)
builder.limit(1)
builder.select(User.table.*)
let query = builder.build()
return query.execute(on: req, as: .psql)
            .first(decoding: User.self)
            .unwrap(or: Abort(.notFound, reason: "User not found"))

So it will build query like: SELECT "User".* FROM "User" WHERE "User"."id" = 1 LIMIT 1.

As you can see you shouldn't worry about parts ordering, it will sort them the right way before building.

More query examples

Let's use SwifQLSelectBuilder for some next examples below, cause it's really convenient especially for complex queries.

1. Let's imagine that you want to query count of users.

/// Just query
let query = SwifQL.select(Fn.count(\User.id) => "count").from(User.table)

/// Execution and decoding for Vapor
struct CountResult: Codable {
  let count: Int64
}
query.execute(on: req, as: .psql)
     .first(decoding: CountResult.self)
     .unwrap(or: Abort(.notFound)) // returns Future<CountResult>

Here you can see two interesting things: Fn.count() and => "count"

Fn is a collection of function builders, so just call Fn. and take a look at the functions list on autocompletion.

=> uses for two things: 1) to write alias through as 2) to cast values to some other types

// TBD: Expand list of examples

Aliasing

Use => operator for that, e.g.:

If you want to write SELECT "User"."email" as eml then do it like this SwifQL.select(\User.email => "eml")

Or if to speak about table name aliasing:

If you want to reach "User" as u then do it like this User.as("u")

And then keypaths will work like

let u = User.as("u")
let emailKeypath = u~\.email

Type casting

Use => operator for that, e.g.:

If you want to write SELECT "User"."email"::text then do it like this SwifQL.select(\User.email => .text)

Predicates

Infix operator	SQL equivalent
>	>
>=	>=
<	<
<=	<=
==	=
== nil	IS NULL
!=	!=
!= nil	IS NOT NULL
&&	AND

And also

|| is for OR

||> is for @>

<|| is for <@

Please feel free to add more predicates in Predicates.swift 😉

Operators

Please feel free to take a look at Fn.Operator enum in Functions.swift

Functions

Please feel free to take a look at the list of function in Functions.swift

Postgres JSON Object

You could build JSON objects by using PostgresJsonObject

SQL example

jsonb_build_object('id', "User"."id", 'email', "User"."email")

SwifQL representation

PgJsonObject().field(key: "id", value: \User.id).field(key: "email", value: \User.email)

Postgres Array

You could build PostgreSQL arrays by using PostgresArray

SQL example

$$[]$$
ARRAY[]
ARRAY[1,2,3]
$$[]$$::uuid[]
ARRAY[]::text[]

SwifQL representation

PgArray(emptyMode: .dollar)
PgArray()
PgArray(1, 2, 3)
PgArray(emptyMode: .dollar) => .uuidArray
PgArray() => .textArray

FILTER

SQL example

COUNT("User"."id") FILTER (WHERE \User.isAdmin = TRUE) as "admins"

SwifQL representation

Fn.count(\User.id).filter(where: \User.isAdmin == true) => "admins"

CASE ... WHEN ... THEN ... END

SQL example

CASE
  WHEN "User"."email" IS NULL
  THEN NULL
  ELSE "User"."email"
END

SwifQL representation

Case(when: \User.email == nil, then: nil, else: \User.email)

Brackets

Yes, we really often use round brackets in our queries, e.g. in where clauses or in subqueries.

SwifQL provides you with | prefix and postfix operators which is representates ( and ).

So it's easy to wrap some part of query into brackets, e.g.: SQL example

"User.role" = 'admin' OR ("User.role" = 'user' AND "User"."age" >= 21)

SwifQL representation

let where = \User.role == .admin || |\User.role == .user && \User.age >= 21|

Keypaths

SQL	Swift
"User"	User.table
"User" as u	User.as("u") you could declare it as let u = User.as("u")
"User".*	User.table.*
u.*	u.*
"User"."email"	\User.email
u."email"	u~\.email
"User"."jsonObject"->"jsonField"	\User.jsonObject.jsonField
"User"."jsonObject"->"jsonField"	SwifQLPartKeyPath(table: "User", paths: "jsonObject", "jsonField")

Tests

For now tests coverage is maybe around 25%. If you have timе and interest please feel free to send pull requests with more tests.

You could find tests in Tests/SwifQLTests/SwifQLTests.swift

Contributing

Please feel free to contribute!

TODO

I have a few todos in my list for PostgreSQL:

• Conditional Expressions
• Geometric Functions and Operators
• Range Functions and Operators
• Array Functions and Operators