How to Use CubitState Variables Inside Your Cubit in Flutter/Bloc

Описание: Discover how to effectively use variables from your Cubit states in Flutter's Bloc architecture, including practical examples and best practices.
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This video is based on the question https://stackoverflow.com/q/65369690/ asked by the user 'Goldlightdrake' ( https://stackoverflow.com/u/12467357/ ) and on the answer https://stackoverflow.com/a/65369939/ provided by the user 'Adnan Alshami' ( https://stackoverflow.com/u/11775016/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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How to Use CubitState Variables Inside Your Cubit in Flutter/Bloc

In the world of Flutter development, understanding how to properly manage state is crucial. One common scenario developers encounter is how to access variables from a CubitState within a Cubit. If you've ever found yourself stuck trying to use a state variable in your Cubit functions, you're definitely not alone. Let’s break down the problem and provide a clear solution.

The Problem: Accessing State Variables

In your Cubit class, you may experience difficulty when trying to access the state variable of AnswerPicked. Here's a brief look at the issue based on your code:

The AnswerState class has an abstract definition, while AnswerPicked is one of its subclasses that holds a string variable answer.

Your goal is to use this answer variable within the takeAnswer function efficiently.

Relevant Code Snippet

Here’s a recap of the relevant parts of your code:

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

As indicated, the line userAnswersList.add(state.answer); results in an error because state is of type AnswerState, and Dart doesn't know state has an answer variable.

The Solution: Type Casting the State

To solve this, you can type cast the state to AnswerPicked. When state is guaranteed to be an instance of AnswerPicked, you can access its properties directly. Here's how you can do it effectively:

Step-by-Step Breakdown

Check State Type: Use the is keyword to verify state is an instance of AnswerPicked.

Type Cast: After checking, use (state as AnswerPicked) to cast state to AnswerPicked which allows access to the answer variable.

Updated takeAnswer Function

Here's a corrected version of your takeAnswer function:

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

Explanation of Changes

Type Casting: By using (state as AnswerPicked).answer, you inform Dart that state is indeed an instance of AnswerPicked, enabling direct access to the answer property.

Consistency: Ensure that within your takeAnswer logic, you consistently type-check and cast state as needed to access any variables specific to the AnswerPicked state.

Conclusion

Accessing variables from your Cubit's state can be a source of challenge, especially when you're new to state management in Flutter. By employing type casting, you can navigate around the limitations imposed by the abstract class type. Now you can efficiently access the answer variable and use it in your Cubit functions without needing to pass data through the widget tree.

Feel free to leverage this pattern in your own projects and enhance the way you handle Bloc state management!