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SwifQL/SwifQL

πŸ’Ž A Swift DSL for type-safe, extensible, and transformable SQL queries.

Mihael Isaev

MIT License Swift 5.2 Github Actions Swift.Stream


This lib can be used either stand alone, or with frameworks like Vapor, Kitura, Perfect and others

We recommend to use it with our Bridges lib which is built on top of SwifQL and support all its flexibility

It supports PostgreSQL and MySQL. And it's not so hard to add other dialects πŸ™‚ just check SwifQL/Dialect folder

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 πŸ™‚

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 πŸš€

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

Support SwifQL development by giving a ⭐️

Installation

With Vapor 4 + Bridges + PostgreSQL

.package(url: "https://github.com/vapor/vapor.git", from:"4.0.0-rc"),
.package(url: "https://github.com/SwifQL/VaporBridges.git", from:"1.0.0-rc"),
.package(url: "https://github.com/SwifQL/PostgresBridge.git", from:"1.0.0-rc"),
.target(name: "App", dependencies: [
    .product(name: "Vapor", package: "vapor"),
    .product(name: "VaporBridges", package: "VaporBridges"),
    .product(name: "PostgresBridge", package: "PostgresBridge")
]),

With Vapor 4 + Bridges + MySQL

.package(url: "https://github.com/vapor/vapor.git", from:"4.0.0-rc"),
.package(url: "https://github.com/SwifQL/VaporBridges.git", from:"1.0.0-rc"),
.package(url: "https://github.com/SwifQL/MySQLBridge.git", from:"1.0.0-rc"),
.target(name: "App", dependencies: [
    .product(name: "Vapor", package: "vapor"),
    .product(name: "VaporBridges", package: "VaporBridges"),
    .product(name: "MySQLBridge", package: "MySQLBridge")
]),

Pure

.package(url: "https://github.com/MihaelIsaev/SwifQL.git", from:"2.0.0-beta"),
.target(name: "App", dependencies: [
    .product(name: "SwifQL", package: "SwifQL"),
]),

Pure on NIO2

.package(url: "https://github.com/MihaelIsaev/SwifQL.git", from:"2.0.0-beta"),
.package(url: "https://github.com/MihaelIsaev/SwifQLNIO.git", from:"2.0.0"),
.target(name: "App", dependencies: [
    .product(name: "SwifQL", package: "SwifQL"),
    .product(name: "SwifQLNIO", package: "SwifQLNIO"),
]),

Pure on NIO1 (deprecated)

.package(url: "https://github.com/MihaelIsaev/SwifQL.git", from:"1.0.0"),
.package(url: "https://github.com/MihaelIsaev/SwifQLNIO.git", from:"1.0.0"),
.target(name: "App", dependencies: ["SwifQL", "SwifQLNIO"]),

With Vapor 3 + Fluent (deprecated)

.package(url: "https://github.com/MihaelIsaev/SwifQL.git", from:"1.0.0"),
.package(url: "https://github.com/MihaelIsaev/SwifQLVapor.git", from:"1.0.0"),
.target(name: "App", dependencies: ["Vapor", "SwifQL", "SwifQLVapor"]),

Philosophy

This lib gives an ability to build absolutely any SQL query from simplest to monster complex.

Example of simple query

SELECT * FROM "User" WHERE "email" = 'john.smith@gmail.com'

build it with pure SwifQL this way

SwifQL.select(User.table.*).from(User.table).where(\User.email == "john.smith@gmail.com")

or with SwifQL + Bridges

SwifQL.select(User.table.*).from(User.table).where(\User.$email == "john.smith@gmail.com")
// or shorter
User.select.where(\User.$email == "john.smith@gmail.com")

Usage

Preparation

πŸ’‘ TIP: It is simpler and more powerful with Bridges

Of course you have to import the lib

import SwifQL

For v1 Your table models should be conformed to Tableable protocol

extension MyTable: Tableable {}

For v2 Your table models should be conformed to Table protocol

extension MyTable: Table {}

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)

or with SwifQL + Bridges

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

How to print raw query

There are two options

1. Get just plain query
let rawSQLString = query.prepare(.psql).plain

or when using SwifQLSelectBuilder() - see below

let rawSQLBuilderString = query.build().prepare(.psql).plain
2. Get object splitted into: formatted raw SQL string with $ symbols, and separated array with 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 πŸ™‚ or use Bridges

How to execute query?

SwifQL is only about building queries. For execution you have to use your favourite database driver.

Below you can see an example for SwifQL + Vapor4 + Bridges + PostgreSQL

πŸ’‘ You can get connection on both Application and Request objects.

Example for Application object e.g. for configure.swift file

// Called before your application initializes.
public func configure(_ app: Application) throws {
    app.postgres.connection(to: .myDb1) { conn in
        SwifQL.select(User.table.*).from(User.table).execute(on: conn).all(decoding: User.self).flatMap { rows in
            print("yaaay it works and returned \(rows.count) rows!")
        }
    }.whenComplete {
        switch $0 {
        case .success: print("query was successful")
        case .failure(let error): print("query failed: \(error)")
        }
    }
}

Example for Request object

func routes(_ app: Application) throws {
    app.get("users") { req -> EventLoopFuture<[User]> in
        req.postgres.connection(to: .myDb1) { conn in
            SwifQL.select(User.table.*).from(User.table).execute(on: conn).all(decoding: User.self)
        }
    }
}

πŸ’‘ In examples above we use .all(decoding: User.self) for decoding results, but we also can use .first(decoding: User.self).unwrap(or: Abort(.notFound)) to get only first row and unwrap it since it may be nil.

Insert Into

Single record

SQL example

INSERT INTO "User" ("email", "name") VALUES ('john@gmail.com', 'John Doe'), ('sam@gmail.com', 'Samuel Jackson')

SwifQL representation

SwifQL.insertInto(User.table, fields: \User.email, \User.name).values("john@gmail.com", "John Doe")

or with SwifQL + Bridges

User(email: "john@gmail.com", name: "John Doe").insert(on: conn)

Batch

SQL example

INSERT INTO "User" ("email", "name") VALUES ('john@gmail.com', 'John Doe'), ('sam@gmail.com', 'Samuel Jackson')

SwifQL representation

SwifQL.insertInto(User.table, fields: \User.email, \User.name).values(array: ["john@gmail.com", "John Doe"], ["sam@gmail.com", "Samuel Jackson"])

or with SwifQL + Bridges

let user1 = User(email: "hello@gmail.com", name: "John")
let user2 = User(email: "byebye@gmail.com", name: "Amily")
let user3 = User(email: "trololo@gmail.com", name: "Trololo")
[user1, user2, user3].batchInsert(on: conn)

Builders

For now there are only one implemented 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 builders

Feel free to make your own builders and send pull request with it here!

Also more conveniences are available in Bridges lib which is created on top of SwifQL and support all its flexibility

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 πŸ˜‰

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

Nesting array of objects inside of query result

Consider such response object you want to achieve:

struct Book {
  let title: String
  let authors: [Author]
}

struct Author {
  let name: String
}

you have to build it with use of subquery to dump Authors in JSON array and then attach them to result query. This will allow you to get all Books with their respective Authors

This example uses Pivot table BookAuthor to join Books with their Authors

    let authors = SwifQL.select(Fn.coalesce(Fn.array_agg(Fn.to_jsonb(Author.table)), PgArray() => .jsonbArray))

    let query = SwifQLSelectBuilder()
    query.select(Book.table.*)

    query.from(Book.table)

    query.join(.left, BookAuthor.table, on: \Book.$id == \BookAuthor.$bookID)
    query.join(.left, Author.table, on: \Author.$id == \BookAuthor.$authorID)

    // then query.group(...) as required in your case

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).end
// or as many cases as needed
Case.when(...).then(...).when(...).then(...).when(...).then(...).else(...).end

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 SwiftQL SwiftQL + Bridges
"User" User.table the same
"User" as u User.as("u") you could declare it as let u = User.as("u") the same
"User".* User.table.* the same
u.* u.* the same
"User"."email" \User.email \User.$email
u."email" u.email u.$email
"User"."jsonObject"->"jsonField" \User.jsonObject.jsonField only through full path for now
"User"."jsonObject"->"jsonField" Path.Table("User").column("jsonObject", "jsonField") the same

Tests

For now tests coverage is maybe around 70%. If you have timΠ΅ and interest please feel free to send pull requests with more tests.

You could find tests in Tests folder

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" = 'john.smith@gmail.com' 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
  • 'john.smith@gmail.com' is SwifQLPartUnsafeValue (it means that this value should be passed as $1 to the database)

That's crazy, but awesome, right? πŸ˜„ But it's under the hood, so no worries! πŸ˜ƒ 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" = 'john.smith@gmail.com'
  • MySQL: SELECT User.* FROM User WHERE User.email = 'john.smith@gmail.com'

Contributing

Please feel free to contribute!

Github

link
Stars: 248
Last commit: 1 week ago

Releases

πŸ‘¨β€πŸ”§Implement SwifQLNull - 2020-10-31T03:59:02

By default when you compare SwifQLable with nil it uses IS NULL

"hello" == nil
// produce: 'hello' IS NULL

to reach exact = NULL use this way

"hello" == SwifQLNull
// produce: 'hello' = NULL