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Encountering the `multiple heroes` error in Flutter without using hero widgets? This guide explains how to resolve this issue effectively.
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How to Resolve the Multiple Heroes Error in Flutter Navigation

If you've been developing a Flutter app, you might have encountered an error message similar to “There are multiple heroes that share the same tag within a subtree.” This error can be particularly perplexing, especially if you're not using any Hero or FloatingActionButton widgets in your code. In this guide, we'll dive into what causes this error and provide a simple solution to fix it.

Understanding the Error

The multiple heroes error occurs when Flutter tries to animate objects between two screens (using PageRoute navigation) and detects that two or more Hero widgets share the same tag within a single subtree. This can happen even if you're not explicitly using Hero widgets. The Flutter framework looks for unique tags associated with these widgets to perform animations, and any duplicate tags can lead to the error.

Example Error Message

Here’s a snapshot of what the error may look like when it occurs:

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Your Flutter Navigation Process

Let's take a look at the navigation process outlined in your code. It becomes clear that navigating to a new page is methodically handled using a route generator and an async method that triggers a screen transition.

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The Route Generator

Your RouteGenerator function creates a mapping for navigating to different pages, including:

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How to Fix the Error

To rectify this multiple heroes error without needing to deeply dive into Hero widgets, we recommend isolating the FirstGiftPage into its own file. Here’s how to do this in a few simple steps:

Step 1: Create a New File

Create a new Dart file in your project directory. You can name it first_gift_page.dart.

Step 2: Move Your Widget Code

Cut the entire FirstGiftPage class code from your existing file and paste it into first_gift_page.dart.

Step 3: Import the New File

At the top of your original file where you had the classes, import the first_gift_page.dart file:

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Step 4: Test Your Navigation

Finally, run your app and test the navigation to ensure the error is resolved. By isolating the page in its own file, you help Flutter manage its widget trees better and avoid duplicate tags inadvertently created from multiple widget instances.

Conclusion

The multiple heroes error can be a tricky hurdle, especially if you're not explicitly using hero animations in your app. By simply isolating your pages into their own files, you can prevent the confusion caused by overlapping widget trees in Flutter’s navigation.

Remember, careful organization of your code will also make it easier to manage and debug in the long run. If you run into similar issues, always consider restructuring your files and ensuring that each widget has its unique identifiers. Happy coding!