http_middleware

A middleware library for Dart http library.

Getting Started

http_middleware is a module that lets you build middleware for Dart's http package.

Installing

Include this library in your package.

http_middleware: any

Importing

import 'package:http_middleware/http_middleware.dart';

Using http_middleware

Create an object of HttpWithMiddleware by using the build factory constructor.

The build constructor takes in a list of middlewares that are built for http_middleware. One very nice middleware you can use is the http_logger package. We will use that here for demonstration.

(You can also build your own middleware for http_middleware. Check out Build your own middleware)

HttpWithMiddleware http = HttpWithMiddleware.build(middlewares: [
    HttpLogger(logLevel: LogLevel.BODY),
]);

That is it! Now go ahead and use this http object as you would normally do.

//Simple POST request
var response = await http.post('https://jsonplaceholder.typicode.com/posts/',
    body: {"testing", "1234"});

//Simple GET request
var response = await http.get('https://jsonplaceholder.typicode.com/posts/');

Request Timout

With http_middleware you can also specify the timeout of requests. So if you want a request to be timeout in 30 seconds:

HttpWithMiddleware http = HttpWithMiddleware.build(
  requestTimeout: Duration(seconds: 30),
  middlewares: [
    HttpLogger(logLevel: LogLevel.BODY),
]);

You need to catch the exception thrown to know if connection timed out.

try {
 var response = await http.get('https://jsonplaceholder.typicode.com/posts/');
} catch(e) {
 if (e is TimeoutException) {
   //Timed out
 }
}

HttpWithMiddleware supports all the functions that http provides.

http.get(...);
http.post(...);
http.put(...);
http.delete(...);
http.head(...);
http.patch(...);
http.read(...);
http.readBytes(...);

Using a Client

If you want to use a http.Client in order to keep the connection alive with the server, use HttpClientWithMiddleware.

HttpClientWithMiddleware httpClient = HttpClientWithMiddleware.build(middlewares: [
    HttpLogger(logLevel: LogLevel.BODY),
]);

var response = await httpClient.post('https://jsonplaceholder.typicode.com/posts/',
    body: {"testing", "1234"});

var response = await httpClient.get('https://jsonplaceholder.typicode.com/posts/');

//Don't forget to close the client once done.
httpClient.close();

Building your own middleware

Building your own middleware with http_middleware is very easy, whether you want to create a package for http_middleware or you want to build a middleware solely for your own project.

Once you have the necessary imports, all you have to do is extend the MiddlewareContract class which will give you access to 2 functions.

interceptRequest(RequestData) is the method called before any request is made. interceptResponse(ResponseData) is the method called after the response from request is received.

You can then @override all the required functions you need to add middleware to.

Example (A simple logger that logs data in all requests):

class Logger extends MiddlewareContract {
  @override
  interceptRequest({RequestData data}) {
    print("Method: ${data.method}");
    print("Url: ${data.url}");
    print("Body: ${data.body}");
  }

  @override
  interceptResponse({ResponseData data}) {
    print("Status Code: ${data.statusCode}");
    print("Method: ${data.method}");
    print("Url: ${data.url}");
    print("Body: ${data.body}");
    print("Headers: ${data.headers}");
  }
}

You can also modify the RequestData before the request is made and every ResponseData after every response is received. For Example, if you want to wrap your data in a particular structure before sending, or you want every request header to have Content-Type set to application/json.

class Logger extends MiddlewareContract {
  @override
  interceptRequest({RequestData data}) {
    //Adding content type to every request
    data.headers["Content-Type"] = "application/json";
    
    data.body = jsonEncode({
      uniqueId: "some unique id",
      data: data.body,
    });
  }

  @override
  interceptResponse({ResponseData data}) {
    //Unwrapping response from a structure
    data.body = jsonDecode(data.body)["data"];
  }
}

Packages built on http_middleware

• http_logger : Easy request and response logging.

If your package uses http_middleware, open an issue and tell me, i will be happy to add it to the list.