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Discover how to call multiple methods in a BlocListener in Flutter effectively, including showing a Snackbar and navigating back.
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How to Call Two Methods in a BlocListener in Flutter: Tips and Tricks

When developing Flutter applications, one common scenario you might encounter is needing to perform multiple actions when a specific state is emitted from a listener—like showing a Snackbar and navigating back to the previous screen. If you've found yourself stuck in a situation where you can only execute one of the tasks, you're not alone!

In this post, we will break down the solution on how to effectively call two methods within a BlocListener, focusing on the problem faced while attempting to show a Snackbar message and pop the current route.

Understanding the Problem

You may be using the Bloc pattern in Flutter to manage state, and have implemented a BlocListener to react to changes. Here’s a gist of the scenario you might be facing:

You have a state called UploadSuccess.

You want to show a Snackbar indicating the success of an operation (like an image upload).

You also want to pop (close) the current route.

Here's a snippet of code illustrating your attempt:

[[See Video to Reveal this Text or Code Snippet]]

You noticed that while one of the methods works fine, invoking both results in nothing happening at all. So, how can you achieve this functionality?

Solution: Await the Snackbar Display

The key to resolving this issue lies in understanding the asynchronous nature of UI operations within Flutter. Specifically, if the method to show the Snackbar (RioHelpers.showSuccessFlushBar) is asynchronous, the current method will not wait for it to complete before executing the subsequent line to pop the route.

Step-by-Step Solution

Adjust Method to Include await:
Modify your code to use await to ensure that the Snackbar displays for a brief moment before executing the navigation back.

Use a Delay:
Implement a delay to allow the Snackbar to be visible before moving to the next action. Here’s how you can do it:

[[See Video to Reveal this Text or Code Snippet]]

Break Down of the Solution

Awaiting the Snackbar:
The await keyword pauses the execution of the current function until the Snackbar completes its operation.

Adding a Delay:
The Future.delayed method allows the app to wait for a specific duration. Here, 1 second is used to ensure the Snackbar is visible long enough for the user to see the message.

Conclusion

By employing the await keyword in conjunction with a delay, you can successfully call two methods within your BlocListener. This approach enhances the user experience by providing feedback through UI elements while managing navigation efficiently.

Feel free to try this out in your current Flutter projects, and remember that handling asynchronous operations effectively can greatly improve the usability and responsiveness of your app!

Happy coding!