Dart REST API Server CRUD Application with aqueduct

Dart is the programming language created by Google and its very popular nowadays because it's providing the platform using which we can create a single code base for developing an application for Android, IOS and Web with the help of Flutter SDK. Today in this article we are going to explore how to create a REST API using the dart without Flutter.

Here in this part of the article, we will explore two things.

• Expose Simple REST API using the DART programming language
• Connect Dart with the Postgress using the Model

Create REST API in DART with aqueduct

So for creating the rest API using the dart we are going to use the aqueduct package available at pub.dev. This package provides lots of functionality which help us for creating the REST API server.

Let's start the creation of our REST API server. We required some setup before starting the coding.

• Dart should be installed into your server or local environment
• We required a Postgres database installed in your dev environment.

Activate the Aqueduct package globally

First of all, we need to activate the aqueduct package globally using the below command.

pub global activate aqueduct

Create the package with the default example Route

We need to create a dart package with the help of aqueduct command-line tool.

aqueduct create nplix

Above command will create a dart project which enables us further for creating the rest API. This will create some important file for our projects. We will let you know some information about some important files.

• main.dart :- This file is inside the bin folder and its main file of our project which will run our project.
• nplix.dart:- This file is very important files of the project which will export the important package which was used by the application.
• channel.dart:- This is file where we are going define the route of our project.

Defining the new route and testing the default API

This file is the entry point of our server application and its content flowing lines of the code by default.

import 'nplix.dart';
class NplixChannel extends ApplicationChannel {
   @override
  Future prepare() async {
    logger.onRecord.listen((rec) => print("$rec ${rec.error ?? ""} ${rec.stackTrace ?? ""}"));
  }
  @override
  Controller get entryPoint {
    final router = Router();
    router
      .route("/example")
      .linkFunction((request) async {
        return Response.ok({"key": "value"});
      });

    return router;
  }
}

If you look at the above code we have two override method prepare() and entryPoint(). The prepare method run before the entryPoint and its used to initialize the service of our rest API server application.

Let run the server and test the default route of our API.is http://localhost:8888/example and if go there you will get the below response.

{"key":"value"}

Perfect, Our rest API is working correctly. Let define our own AP.

Add route to our dart REST API server

For adding the new route to our app we just need to modify our entry point method and below lines of the code.

 router
    .route("/user")
    .linkFunction((request) async{
      return Response.ok({"msg": "Welcome to Dart REST API!"});
    });

If you look at the above code we have just added a new route with the user and link this route with the function which will respond with the msg. If you are working into visual code then just press the F5 and if it's already running then restart the application. Go the http://localhost:8888/user and you will get the response.

Link user route to Controller of our Dart REST API Server

For linking the route to the Controller we need to create a controller, so let's create our user controller. So let's create a folder inside of lib folder with the name of the controller and a class UserController.dart in that folder.

//user_controller.dart
import 'package:nplix/nplix.dart';

class UserController extends Controller{
  @override
  FutureOr<RequestOrResponse> handle(Request request) {
    return Response.ok({"msg":"Welcome to Route Controller!"});
  }
 
}

Perfect, We are ready to hook this controller with our user route. So let's modify the user root as given below in channel.dart file.

router
    .route("/user")
    .link(() => UserController());

So what happing here when the user hit the http://localhost:8888/user URL our router will provide the control to the UserController class and UserController class will be responsible for responding to the request. This is a very simple controller that we have created there a lot more that we can do, it just the beginning of the controller. Let' test the application by re-running our server.

C:\Users\Pawan>curl http://localhost:8888/user
{"msg":"Welcome to Route Controller!"}
C:\Users\Pawan>

Perfect, Our controller is working fine. Let's move further and define the request type like get, post and more in the controller.

I don' want to make this boring so ending this article here in the next part of this article we will hook the route with the different type of the HTTP method and will connect our REST API with the database. To be continued ...