TakeLatest function

Fork TakeLatest(Function saga, { List? args, Map<Symbol, dynamic>? namedArgs, Function? Catch, Function? Finally, Channel? channel, dynamic pattern, bool detached = false, String? name, Result? result, })

Forks a saga on each action dispatched to the Store or the channel provided that matches pattern. And automatically cancels any previous saga task started previously if it's still running.

Each time an action is dispatched to the store. And if this action matches pattern, TakeLatest starts a new saga task in the background. If a saga task was started previously (on the last action dispatched before the actual action), and if this task is still running, the task will be cancelled.

• pattern is used to filter actions. Only matching actions will be processed. See docs for Take.

• saga is a Generator function.

• args and namedArgs are arguments to be passed to the started task. TakeEvery will add the incoming action to the argument list (i.e. the action will be a named {dynamic action} argument provided to saga)

• If a channel is provided then actions will be put from provided channel.

• Catch will be invoked for uncaught errors.

• Finally will be invoked in any case before task execution is end.

• If detached is false TakeLatest will return a forked task, otherwise it will return a spawned task. By default detached is false.

• name is an optional name for the task meta.

Example

In the following example, we create a basic task fetchUser. We use TakeLatest to start a new fetchUser task on each dispatched UserRequested action. Since TakeLatest cancels any pending task started previously, we ensure that if a user triggers multiple consecutive UserRequested actions rapidly, we'll only conclude with the latest action.

 import 'package:redux_saga/redux_saga.dart';
 import 'Api.dart';

 //...

 fetchUser({dynamic action}) sync* {
   // ...
 }

 watchLastFetchUser() sync* {
   yield TakeLatest(fetchUser, pattern: UserRequested);
 }

Notes

TakeLatest is a high-level API built using Take and Fork.

Implementation

Fork TakeLatest(Function saga,
    {List<dynamic>? args,
    Map<Symbol, dynamic>? namedArgs,
    Function? Catch,
    Function? Finally,
    Channel? channel,
    dynamic pattern,
    bool detached = false,
    String? name,
    Result? result}) {
  return Fork(_TakeLatest,
      args: <dynamic>[saga],
      namedArgs: <Symbol, dynamic>{
        #args: args,
        #namedArgs: namedArgs,
        #Catch: Catch,
        #Finally: Finally,
        #channel: channel,
        #pattern: pattern,
        #name: name
      },
      detached: detached,
      result: result);
}