Скачать или смотреть Understanding takeUntilDestroyed in Non-Component Angular Classes

Learn how to use `takeUntilDestroyed` in Angular classes not directly tied to components or directives, and get practical solutions to common issues.
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Using takeUntilDestroyed in Non-Component Classes in Angular

In Angular, takeUntilDestroyed is an incredibly useful operator for managing subscriptions and preventing memory leaks, especially within the context of components and directives. But what if you're working within a plain class that doesn’t have the benefits of Angular's dependency injection? You might wonder, "Is it possible to use takeUntilDestroyed in a class (not a component or directive)?" In this post, we will explore this issue and provide a step-by-step solution.

The Problem

Many developers encounter issues when they attempt to use inject() within regular classes. The error message they receive can be confusing:

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This error often occurs when you try to obtain dependencies like DestroyRef in a class that is not part of Angular's component or directive lifecycle.

The Solution

To effectively use takeUntilDestroyed in your custom classes, you can leverage constructor parameters to pass in required dependencies. Here’s how:

Step-by-Step Implementation

Modify Your Class Constructor:
Instead of trying to use inject() directly, pass DestroyRef to your class through the constructor. This allows you to manage the lifecycle properly without running into injection context issues.

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Set Up Your Test Environment:
When creating an instance of your class in tests, ensure you provide a DestroyRef instance correctly. Here's a sample setup:

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Key Benefits

Avoid Memory Leaks: By using takeUntilDestroyed, you ensure that subscriptions automatically unsubscribe once the DestroyRef signals that the component is destroyed.

Decoupled Logic: This pattern allows you to create reusable service-like classes that maintain clean, manageable code without being tied to Angular's component lifecycle directly.

Increased Readability: Your class structure becomes clearer, and adheres to Angular's best practices regarding dependency injection.

Conclusion

Using takeUntilDestroyed within a plain class in Angular is possible when you pass the DestroyRef through the class constructor. This approach not only resolves the dependency injection issue but also contributes to the maintainability of your code. By following the steps outlined above, you can effectively manage your subscriptions, ensuring your application remains efficient and error-free.

If you have any questions or need further assistance, feel free to reach out or check out more guides on Angular best practices!