Corvus

Corvus is the first truly declarative server-side framework for Swift. It provides a declarative, composable syntax which makes it easy to get APIs up and running. It is based heavily on the existing work from Vapor.

Example

Below is an example of a full-featured API that manages Bank Accounts and Transactions belonging to certain users. It also showcases the ease of using authentication and setting authorization rules for specific routes.

let xpenseApi = Api("api") {
    User<CorvusUser>("users")

    Login<CorvusToken>("login")

    BearerAuthGroup<CorvusToken> {
        AccountsEndpoint()
        TransactionsEndpoint()
    }
}

Because Corvus is composable, it is easy to use a group of components as its own component:

final class AccountsEndpoint: Endpoint {
    let parameter = Parameter<Account>()

    var content: Endpoint {
        Group("accounts") {
            Create<Account>().auth(\.$user)
            ReadAll<Account>().auth(\.$user)

            Group(parameter.id) {
                ReadOne<Account>(parameter.id).auth(\.$user)
                Update<Account>(parameter.id).auth(\.$user)
                Delete<Account>(parameter.id).auth(\.$user)
            }
        }
    }
}

How to set up

After your Swift Project, in the Package.Swift file, you will need to add the dependencies for Corvus and a Fluent database driver of your choice. Below is an example with an SQLite driver:

// swift-tools-version:5.2
import PackageDescription

let package = Package(
    name: "XpenseServer",
    platforms: [
        .macOS(.v10_15)
    ],
    products: [
        .library(name: "XpenseServer", targets: ["XpenseServer"])
    ],
    dependencies: [
        .package(url: "https://github.com/Apodini/corvus.git", from: "0.0.14"),
        .package(url: "https://github.com/vapor/vapor.git", from: "4.0.0"),
        .package(url: "https://github.com/vapor/fluent-sqlite-driver.git", from: "4.0.0-rc")
    ],
    targets: [
        .target(name: "Run",
                dependencies: [
                    .target(name: "XpenseServer")
                ]),
        .target(name: "XpenseServer",
                dependencies: [
                    .product(name: "Corvus", package: "corvus"),
                    .product(name: "FluentSQLiteDriver", package: "fluent-sqlite-driver")
                ]),
        .testTarget(name: "XpenseServerTests",
                    dependencies: [
                        .target(name: "XpenseServer"),
                        .product(name: "XCTVapor", package: "vapor"),
                        .product(name: "FluentSQLiteDriver", package: "fluent-sqlite-driver")
                    ])
    ]
)

Additionally, under the application’s Source folder (by default that is Sources/App), two setup functions need to be present:

configure.swift, in which you can configure middlewares, databases and migrations used in the application:

import Corvus
import Vapor
import FluentSQLiteDriver

public func configure(_ app: Application) throws {
    app.middleware.use(CorvusUser.authenticator())
    app.middleware.use(CorvusToken.authenticator())

    app.databases.use(.sqlite(.file("db.sqlite")), as: .sqlite)
    app.migrations.add(CreateAccount())
    app.migrations.add(CreateTransaction())
    app.migrations.add(CreateCorvusUser())
    app.migrations.add(CreateCorvusToken())

    try app.autoMigrate().wait()
}

And routes.swift, which registers the routes from the Corvus API:

import Corvus
import Vapor

public func routes(_ app: Application) throws {
    try app.register(collection: xpenseApi)
}

Finally the application’s main.swift file (which is usually under the path Sources/Run) should look like this:

import App
import Vapor

var environment = try Environment.detect()
try LoggingSystem.bootstrap(from: &environment)
let app = Application(environment)
try configure(app)
try routes(app)
defer {
    app.shutdown()
}
try app.run()

How to use

In general, there are two types of building blocks for a Corvus API: Group components, which allow users to group more groups or concrete endpoints under a common route path, or components that provide concrete functionality, like Create or ReadAll. Check out the docs and the example project to learn more!

How to contribute

Review our contribution guidelines for contribution formalities.

Sources

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Vapor

Fluent