File add API server in Vapor 4

A easy file add server written in Swift

For this straightforward file add tutorial we’ll solely use the Vapor Swift package deal as a dependency. 📦

import PackageDescription

let package deal = Bundle(
    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 challenge with the required information utilizing the Vapor toolbox, alternatively you may create every part by hand utilizing the Swift Bundle Supervisor, lengthy story brief, we simply want a starter Vapor challenge with out extra dependencies. Now should you open the Bundle.swift file utilizing Xcode, we will setup our routes by altering the configure.swift file.

import Vapor

public func configure(_ app: Utility) 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.acquire()
            .unwrap(or: Abort(.noContent))
            .flatMap { req.fileio.writeFile($0, at: path) }
            .map { key }
    }
}

First we use the FileMiddleware, it will 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. Do not forget to present correct file system permissions if vital, in any other case we can’t have the ability to write our knowledge contained in the listing. 📁

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

If you wish to add giant information to the server it’s best to 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, nevertheless it’s not that sophisticated, if you’re all for that resolution, it’s best to learn the Recordsdata API and the physique streaming part utilizing official Vapor docs website.

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 executed 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 widespread networking duties. We will use the URLSession uploadTask methodology to ship a brand new URLRequest with an information 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 a must to explicitly cross a “from: Knowledge?” argument if 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 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 package deal (or in fact 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 (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 activity = 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)
}

activity.resume()
dispatchMain()

The above instance makes use of the Dispatch framework to attend till the asynchronous file add finishes. It is best to change the placement (and the extension) of the file if vital earlier than you run this script. Since we outlined the add route as a POST endpoint, now we have to set the httpMethod property to match this, additionally we retailer the file knowledge within the httpBody variable earlier than we create our activity. The add URL ought to comprise a key, that the server can use as a reputation for the file. You’ll be able to add extra properties in fact or use header values to verify if the consumer has correct authorization to carry out the add operation. Then we name the add activity 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 helpful if it involves iOS improvement. 📱

Contained in the completion handler now we have to verify for just a few issues. To start with if there was an error, the add should 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 wish to retrieve the important thing from the response physique so we verify the information object and convert it to a utf8 string if doable. 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 wish to return a JSON response with extra knowledge. 😅

Vanilla JavaScript file uploader

Yet another factor… you should use Leaf and a few Vanilla JavaScript to add information utilizing the newly created add endpoint. Really it is very easy to implement a brand new endpoint and render a Leaf template that does the magic. You may want some primary HTML and some traces of JS code to submit the contents of the file as an array buffer. It is a primary instance.

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

        operate uploadImage() {
            var xhr = new XMLHttpRequest();
            xhr.open("POST", "/add?key=take a look at.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 may see it is an ordinary 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. Normally persons are utilizing a multipart-encoded kind to entry information on the server, however when it’s a must 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, it’s best to learn my earlier article.

I even have a submit about completely different file add strategies utilizing commonplace HTML kinds and a Vapor 4 server as a backend. I hope you will discover the suitable resolution that you simply want to your utility. 👍