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(
    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’ll be able to setup the mission with the required recordsdata utilizing the Vapor toolbox, alternatively you possibly can create the whole lot by hand utilizing the Swift Bundle Supervisor, lengthy story quick, we simply want a starter Vapor mission with out further dependencies. Now for those who 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 = attempt req.question.get(String.self, at: "key")
        let path = req.software.listing.publicDirectory + key
        return req.physique.gather()
            .unwrap(or: Abort(.noContent))
            .flatMap { req.fileio.writeFile($0, at: path) }
            .map { key }
    }
}

First we use the FileMiddleware, this can enable us to server recordsdata utilizing the Public listing inside our mission folder. If you do not have a listing named Public, please create one, because the file add server will want that. Remember to present correct file system permissions if mandatory, in any other case we cannot have the ability to 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 information that our server can settle for, you do not actually need to use this methodology for big recordsdata as a result of uploaded recordsdata will probably be saved within the system reminiscence earlier than we write them to the disk.

If you wish to add giant recordsdata to the server it’s best to take into account streaming the file as an alternative of amassing the file knowledge from the HTTP physique. The streaming setup would require a bit extra work, nevertheless it’s not that sophisticated, in case you are excited about that answer, it’s best to learn the Information API and the physique streaming part utilizing official Vapor docs website.

This time we simply desire a useless 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 the whole lot was carried out 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 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 you need to explicitly go a “from: Knowledge?” argument while 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 a bit 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 selection from Apple… 🤐

We will put this little snippet right into a easy executable Swift package deal (or after all we will create a complete software) to check our add server. In our case I am going to place the whole lot right into a foremost.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 = attempt 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) { 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)
}

job.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 situation (and the extension) of the file if mandatory 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 job. 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 after all or use header values to examine if the person 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 that you could run them on the background if wanted, that is fairly useful if it involves iOS improvement. 📱

Contained in the completion handler now we have to examine for a couple of issues. To begin 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 legitimate 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 examine the info 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 software you would possibly need to return a JSON response with further knowledge. 😅

Vanilla JavaScript file uploader

Another factor… you need to use Leaf and a few Vanilla JavaScript to add recordsdata 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 will want some fundamental HTML and some traces 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/photos/logos/emblem.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').recordsdata[0];
            if (file) {
                var reader = new FileReader();
                reader.onload = operate() {
                    xhr.ship(reader.consequence);
                }
                reader.readAsArrayBuffer(file);
            }
        }
      </script>
  </physique>
</html>

As you possibly can see it is a regular XHR request mixed with the FileReader JavaScript API. We use the FileReader to transform our enter to a binary knowledge, this fashion our server can write it to the file system within the anticipated format. Usually persons are utilizing a multipart-encoded type to entry recordsdata on the server, however when you need to work with an API you can too switch uncooked file knowledge. If you wish to study extra about XHR requests and AJAX calls, it’s best to learn my earlier article.

I even have a submit about totally different file add strategies utilizing customary HTML kinds and a Vapor 4 server as a backend. I hope you may discover the appropriate answer that you simply want in your software. 👍