orchestrator

Registers a function as an orchestrator.

Usage

orchestrator(actionCreator, target)

Arguments

• actionCreator (ActionCreator): The action creator of the action to subscribe to.
• target ((ActionMessage) => void): The function to register as an orchestrator.

Return value

• ((ActionMessage) => void): The target function.

Example

let addTodo = actionCreator(
    'ADD_TODO',
    (text: string) => ({ text: text }));

orchestrator(addTodo, (actionMessage) => {
    addTodoOnServer(actionMessage.text);
};

Notes

• The target function gets called whenever an action of the subscribed type is dispatched.
• Orchestrators are responsible for dealing with side effects and any other coordination the app may require. Side effects might include service calls, setting timers, dealing with browser local storage, etc.
• Orchestrators cannot modify the store directly, but they can dispatch further actions which, indirectly, will cause the store to get modified.
• In a large app with many stores, orchestrators provide a way to coordinate between the different stores. For example, in response to an action an orchestrator might dispatch a series of additional actions in a specific order, or it might read data from one store and conditionally dispatch actions to affect another store.
• Note that an orchestrator is registered to an action by passing that action's action creator as the first argument. This is a little unusual, but convenient because it allows TypeScript to infer the type of the action message.
• For convenience, orchestrator returns target. While you don't need to export a orchestrator function, it may be convenient to do so for testing purposes.