File add API server in Vapor 4

A easy file add server written in Swift

For this easy file add tutorial we’ll solely use the Vapor Swift bundle as a dependency. 📦

// swift-tools-version:5.3
import PackageDescription

let bundle = Package deal(
    title: "myProject",
    platforms: [
       .macOS(.v10_15)
    ],
    dependencies: [
        .package(url: "https://github.com/vapor/vapor", from: "4.35.0"),
    ],
    targets: [
        .target(
            name: "App",
            dependencies: [
                .product(name: "Vapor", package: "vapor"),
            ],
            swiftSettings: [
                .unsafeFlags(["-cross-module-optimization"], .when(configuration: .launch))
            ]
        ),
        .goal(title: "Run", dependencies: [.target(name: "App")]),
        .testTarget(title: "AppTests", dependencies: [
            .target(name: "App"),
            .product(name: "XCTVapor", package: "vapor"),
        ])
    ]
)

You’ll be able to setup the venture with the required recordsdata utilizing the Vapor toolbox, alternatively you’ll be able to create every part by hand utilizing the Swift Package deal Supervisor, lengthy story brief, we simply want a starter Vapor venture with out extra dependencies. Now for those who open the Package deal.swift file utilizing Xcode, we will setup our routes by altering the configure.swift file.

import Vapor

public func configure(_ app: Software) throws {

    /// allow file middleware
    app.middleware.use(FileMiddleware(publicDirectory: app.listing.publicDirectory))

    /// set max physique dimension
    app.routes.defaultMaxBodySize = "10mb"

    /// setup the add handler
    app.put up("add") { req -> EventLoopFuture in
        let key = strive req.question.get(String.self, at: "key")
        let path = req.utility.listing.publicDirectory + key
        return req.physique.accumulate()
            .unwrap(or: Abort(.noContent))
            .flatMap { req.fileio.writeFile($0, at: path) }
            .map { key }
    }
}

First we use the FileMiddleware, it will permit us to server recordsdata utilizing the Public listing inside our venture folder. Should you don’t have a listing named Public, please create one, because the file add server will want that. Don’t overlook to present correct file system permissions if obligatory, in any other case we received’t have the ability to write our information contained in the listing. 📁

The subsequent factor that we set is the default most physique dimension. This property can restrict the quantity of knowledge that our server can settle for, you don’t actually need to use this methodology for big recordsdata as a result of uploaded recordsdata might be saved within the system reminiscence earlier than we write them to the disk.

If you wish to add massive recordsdata to the server you must take into account streaming the file as a substitute of gathering the file information from the HTTP physique. The streaming setup would require a bit extra work, however it’s not that difficult, in case you are serious about that answer, you must learn the Information API and the physique streaming part utilizing official Vapor docs web site.

This time we simply desire a lifeless easy file add API endpoint, that collects the incoming information utilizing the HTTP physique right into a byte buffer object, then we merely write this buffer utilizing the fileio to the disk, utilizing the given key from the URL question parameters. If every part was completed with out errors, we will return the important thing for the uploaded file.

File add duties utilizing the URLSession API
The Basis frameworks provides us a pleasant API layer for frequent networking duties. We are able to use the URLSession uploadTask methodology to ship a brand new URLRequest with an information object to a given server, however IMHO this API is kind of unusual, as a result of the URLRequest object already has a httpBody property, however it’s important to explicitly go a “from: Knowledge?” argument once you assemble the duty. However why? 🤔

import Basis

extension URLSession {

    func uploadTask(with request: URLRequest, completionHandler: @escaping (Knowledge?, URLResponse?, Error?) -> Void) -> URLSessionUploadTask {
        uploadTask(with: request, from: request.httpBody, completionHandler: completionHandler)
    }
}

Anyway, I made just a little extension methodology, so once I create the URLRequest I can set the httpBody property of it and safely go it earlier than the completion block and use the contents because the from parameter. Very unusual API design alternative from Apple… 🤐

We are able to put this little snippet right into a easy executable Swift bundle (or after all we will create a complete utility) to check our add server. In our case I’ll place every part right into a primary.swift file.

import Basis
import Dispatch

extension URLSession {

    func uploadTask(with request: URLRequest, completionHandler: @escaping (Knowledge?, URLResponse?, Error?) -> Void) -> URLSessionUploadTask {
        uploadTask(with: request, from: request.httpBody, completionHandler: completionHandler)
    }
}


let fileData = strive Knowledge(contentsOf: URL(fileURLWithPath: "/Customers/[user]]/[file].png"))
var request = URLRequest(url: URL(string: "http://localhost:8080/add?key=(UUID().uuidString).png")!)
request.httpMethod = "POST"
request.httpBody = fileData

let job = URLSession.shared.uploadTask(with: request) { information, response, error in
    guard error == nil else {
        fatalError(error!.localizedDescription)
    }
    guard let response = response as? HTTPURLResponse else {
        fatalError("Invalid response")
    }
    guard response.statusCode == 200 else {
        fatalError("HTTP standing error: (response.statusCode)")
    }
    guard let information = information, let outcome = String(information: information, encoding: .utf8) else {
        fatalError("Invalid or lacking HTTP information")
    }
    print(outcome)
    exit(0)
}

job.resume()
dispatchMain()

The above instance makes use of the Dispatch framework to attend till the asynchronous file add finishes. You need to change the situation (and the extension) of the file if obligatory earlier than you run this script. Since we outlined the add route as a POST endpoint, we now have to set the httpMethod property to match this, additionally we retailer the file information within the httpBody variable earlier than we create our job. The add URL ought to include a key, that the server can use as a reputation for the file. You’ll be able to add extra properties after all or use header values to test if the consumer has correct authorization to carry out the add operation. Then we name the add job extension methodology on the shared URLSession property. The great factor about uploadTask is you could run them on the background if wanted, that is fairly useful if it involves iOS growth. 📱

Contained in the completion handler we now have to test for just a few issues. To start with if there was an error, the add will need to have failed, so we name the fatalError methodology to interrupt execution. If the response was not a sound HTTP response, or the standing code was not okay (200) we additionally cease. Lastly we need to retrieve the important thing from the response physique so we test the info object and convert it to a UTF8 string if potential. Now we will use the important thing mixed with the area of the server to entry the uploaded file, this time I simply printed out the outcome, however hey, that is only a demo, in an actual world utility you would possibly need to return a JSON response with extra information. 😅

Vanilla JavaScript file uploader

Another factor… you should utilize Leaf and a few Vanilla JavaScript to add recordsdata utilizing the newly created add endpoint. Really it’s very easy to implement a brand new endpoint and render a Leaf template that does the magic. You’ll want some fundamental HTML and some strains of JS code to submit the contents of the file as an array buffer. It is a fundamental instance.

As you’ll be able to see it’s a regular XHR request mixed with the FileReader JavaScript API. We use the FileReader to transform our enter to a binary information, this fashion our server can write it to the file system within the anticipated format. Normally persons are utilizing a multipart-encoded type to entry recordsdata on the server, however when it’s important to work with an API you may as well switch uncooked file information. If you wish to be taught extra about XHR requests and AJAX calls, you must learn my earlier article.

I even have a put up about totally different file add strategies utilizing normal HTML types and a Vapor 4 server as a backend. I hope you’ll discover the fitting answer that you simply want on your utility. 👍