Redux, by default, supports only synchronous data flow. A container component cannot directly call an asynchronous API and then dispatch actions based on the response.
The Issue with Direct API Calls:
In a UI like the one described, with a field and a button, the container component would attempt to perform the following steps:
<pre class="brush:php;toolbar:false"> class App extends React.Component { render() { return ( <div> <input value={this.props.field} /> <button onClick={this.props.update}>Fetch</button> {this.props.isWaiting && <div>Waiting...</div>} </div> ); } update = () => { AsyncApi.getFieldValue() // Perform async API call .then(result => this.props.dispatch({ // Dispatch action with result type: ActionTypes.UPDATED, payload: result })); } }
This approach is problematic because:
Middleware to the Rescue:
Middleware like Redux Thunk or Redux Promise solve these issues by providing a structured and consistent way to perform asynchronous data flow.
Redux Thunk:
Redux Thunk allows you to dispatch functions instead of actions. These functions can perform asynchronous tasks and dispatch actions as needed.
Redux Promise:
Redux Promise automatically dispatches actions based on the success or failure of a given promise.
Benefits of Middleware:
In Conclusion:
While the direct approach to async flow in Redux is possible, it is generally discouraged due to the aforementioned drawbacks. Middleware provides a more efficient and structured solution for managing async data flow in Redux applications, leading to improved code quality, maintainability, and debugging capabilities.
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