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. 📦

import PackageDescription

let bundle = Package deal(
    identify: "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(identify: "Run", dependencies: [.target(name: "App")]),
        .testTarget(identify: "AppTests", dependencies: [
            .target(name: "App"),
            .product(name: "XCTVapor", package: "vapor"),
        ])
    ]
)

You may setup the challenge with the required information 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 challenge with out extra dependencies. Now should you 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 {

	
    app.middleware.use(FileMiddleware(publicDirectory: app.listing.publicDirectory))

    
    app.routes.defaultMaxBodySize = "10mb"

	
    app.submit("add") { req -> EventLoopFuture<String> 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, this can enable us to server information utilizing the Public listing inside our challenge folder. If you do not have a listing named Public, please create one, because the file add server will want that. Remember to provide correct file system permissions if essential, in any other case we can’t be capable of write our knowledge contained in the listing. 📁

The subsequent factor that we set is the default most physique measurement. This property can restrict the quantity of knowledge that our server can settle for, you do not actually need to use this methodology for giant information as a result of uploaded information will likely be saved within the system reminiscence earlier than we write them to the disk.

If you wish to add massive information to the server you must take into account streaming the file as a substitute of accumulating the file knowledge from the HTTP physique. The streaming setup would require a bit extra work, but it surely’s not that difficult, if you’re considering that resolution, 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 knowledge 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 offers us a pleasant API layer for frequent networking duties. We will use the URLSession uploadTask methodology to ship a brand new URLRequest with a knowledge object to a given server, however IMHO this API is sort of unusual, as a result of the URLRequest object already has a httpBody property, however it’s important to explicitly cross a “from: Information?” argument once you assemble the duty. However why? 🤔

import Basis

extension URLSession {

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

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

We will put this little snippet right into a easy executable Swift bundle (or after all we will create a whole utility) to check our add server. In our case I will place every part right into a most important.swift file.

import Basis
import Dispatch

extension URLSession {

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


let fileData = strive Information(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 process = URLSession.shared.uploadTask(with: request) { knowledge, 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 knowledge = knowledge, let consequence = String(knowledge: knowledge, encoding: .utf8) else {
        fatalError("Invalid or lacking HTTP knowledge")
    }
    print(consequence)
    exit(0)
}

process.resume()
dispatchMain()

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

Contained in the completion handler we’ve got to test for a couple of issues. Initially 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 information object and convert it to a utf8 string if attainable. 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 consequence, however hey, that is only a demo, in an actual world utility you would possibly need to return a JSON response with extra knowledge. 😅

Vanilla JavaScript file uploader

Another factor… you need to use Leaf and a few Vanilla JavaScript to add information utilizing the newly created add endpoint. Truly it is very easy to implement a brand new endpoint and render a Leaf template that does the magic. You may want some fundamental HTML and some strains of JS code to submit the contents of the file as an array buffer. This can be a fundamental instance.

<!DOCTYPE html>
<html>
  <head>
    <meta charset="utf-8">
    <meta identify="viewport" content material="width=device-width, initial-scale=1">
    <title>File add</title>
  </head>
  <physique>
      <h1>File add</h1>
      <enter kind="file" id="file" identify="file" settle for="picture/*" /><br><br>
      <img id="preview" src="https://theswiftdev.com/photographs/logos/brand.png" width="256px">
      <script>
        doc.getElementById('file').addEventListener("change", uploadImage);

        operate uploadImage() {
            var xhr = new XMLHttpRequest();
            xhr.open("POST", "/add?key=check.png", true);
            xhr.onreadystatechange = operate() {
                if(xhr.readyState == 4 && xhr.standing == 200) {
                    doc.getElementById('preview').src = "/" + this.responseText;
                }
            };

            var file = doc.getElementById('file').information[0];
            if (file) {
                var reader = new FileReader();
                reader.onload = operate() {
                    xhr.ship(reader.consequence);
                }
                reader.readAsArrayBuffer(file);
            }
        }
      </script>
  </physique>
</html>

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

I even have a submit about totally different file add strategies utilizing normal HTML types and a Vapor 4 server as a backend. I hope you may discover the fitting resolution that you simply want in your utility. 👍