Ways of Combining Multiple Requests in Flutter: A Comprehensive Guide

3 min readJul 13, 2023

Combining Multiple Requests in Flutter: A Comprehensive Guide

In Flutter app development, it is common to encounter scenarios where you need to combine the results of multiple asynchronous requests before proceeding with further operations. Combining requests efficiently can enhance performance, reduce network overhead, and improve user experience. In this article, we will explore various techniques and best practices to combine multiple requests in Flutter.

Sequential Combination

One straightforward approach is to execute requests sequentially and combine their results as they complete. This can be achieved using async and await keywords to await each request before initiating the next one. Consider the following example:

Future<List<dynamic>> combineRequestsSequentially() async {
  List<dynamic> results = [];

  var result1 = await makeRequest1();
  results.add(result1);

  var result2 = await makeRequest2();
  results.add(result2);

  var result3 = await makeRequest3();
  results.add(result3);

  return results;
}

Parallel Combination

When the order of requests is not critical, executing them in parallel can significantly improve performance. Flutter provides multiple options to achieve parallel execution, such as using Future.wait() or leveraging the async package's FutureGroup class. Here's an example:

Future<List<dynamic>> combineRequestsInParallel() async {
  List<Future<dynamic>> futures = [];

  futures.add(makeRequest1());
  futures.add(makeRequest2());
  futures.add(makeRequest3());

  List<dynamic> results = await Future.wait(futures);
  return results;
}

Concurrent Combination

Combining requests concurrently allows for simultaneous execution while ensuring all requests are completed before proceeding. This can be useful when requests depend on each other or when a specific order is required. Flutter’s Future class provides methods like then() and whenComplete() to handle this scenario. Here's an example:

Future<List<dynamic>> combineRequestsConcurrently() {
  List<dynamic> results = [];

  makeRequest1().then((result1) {
    results.add(result1);

    makeRequest2().then((result2) {
      results.add(result2);

      makeRequest3().then((result3) {
        results.add(result3);

        // Further processing with combined results
      });
    });
  });

  return Future.wait(results);
}

Advanced Techniques

For complex scenarios involving a large number of requests or complex dependencies, you can utilize Flutter packages like dio, http, or rxdart that provide additional features such as request cancellation, request pipelining, or reactive programming paradigms to combine requests more efficiently.

Request cancellation refers to the act of terminating or aborting an ongoing network request before it is completed. It allows a client or a server to cancel a request that is in progress to prevent unnecessary processing or to free up resources.
Request pipelining is a technique used in network communication that allows multiple HTTP requests to be sent over a single connection without waiting for each response individually.
Reactive programming is a programming approach that concentrates on constructing systems and applications capable of reacting and responding to data changes or events in a declarative and asynchronous way. Its emphasis lies in the seamless propagation of changes, enabling components to automatically update or respond to data modifications without relying on explicit, imperative programming techniques.

Conclusion

Combining multiple requests in Flutter is an essential skill for optimizing app performance and managing network operations effectively. In this article, we explored different techniques, including sequential, parallel, and concurrent combinations, to help you achieve this goal. Depending on your specific requirements and the nature of your app, choose the appropriate technique and leverage the vast Flutter ecosystem to simplify and enhance your request combining process. Happy coding!