About code generation

Code generation is the idea of using a tool to generate code for us.
In Dart, it comes with the downside of requiring an extra step to "compile" an application. Although this problem may be solved in the near future, as the Dart team is working on a potential solution to this problem.

In the context of Riverpod, code generation is about slightly changing the syntax for defining a "provider". For example, instead of:

final fetchUserProvider = FutureProvider.autoDispose.family<User, int>((ref, userId) async {
  final json = await http.get('api/user/$userId');
  return User.fromJson(json);
});

Using code generation, we would write:

@riverpod
Future<User> fetchUser(FetchUserRef ref, {required int userId}) async {
  final json = await http.get('api/user/$userId');
  return User.fromJson(json);
}

When using Riverpod, code generation is completely optional. It is entirely possible to use Riverpod without.
At the same time, Riverpod embraces code generation and recommends using it.

For information on how to install and use Riverpod's code generator, refer to the getting started page. Make sure to enable code generation in the documentation's sidebar.

Why use code generation with Riverpod?

You may be wondering: "If code generation is optional in Riverpod, why use it?"

As always with packages: To make your life easier. This includes but is not limited to:

• better syntax, more readable/flexible and with reduced learning curve.

  • No need to worry about FutureProvider vs Provider vs etc. Write your logic, and Riverpod will pick the most suitable provider for you.
  • Passing parameters to providers is now unrestricted. Instead of being limited to using family and passing a single positional parameter, you can now pass any form of parameter. This includes named parametes, optional ones, and even default values.

• stateful hot-reload of the code written in Riverpod.

• better debugging, through the generation of extra metadata that the debugger then picks-up.

• some Riverpod features will be available only with code generation.

At the same time, many applications already use code generation with packages such as Freezed or json_serializable.
In that case, your project probably is already setup for code generation, and using for Riverpod should be simple.