Скачать или смотреть Mastering NgRx: How to Push or Update State Effectively

Discover the proper way to `push or update state` in NgRx and avoid errors while ensuring your application stays efficient and functional.
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Mastering NgRx: How to Push or Update State Effectively

As developers, we often encounter issues while managing application state, especially when working with libraries like NgRx in Angular. One frequent hurdle is the proper way to update state in a way that avoids errors and ensures our application runs smoothly. If you've found yourself grappling with the error message TypeError: Cannot add property 1, object is not extensible, then you’re not alone. In this guide, we'll break down this problem and guide you through the best practices for pushing and updating state in an NgRx environment.

Understanding the Problem

The primary issue at hand arises when trying to directly modify the state in NgRx. Your code might look something like this:

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Why You Can’t Modify State Directly

In NgRx, the state is immutable, which means that you cannot change it directly. When you try to manipulate the state object directly, such as pushing new values into it, NgRx will throw an error. This immutability is a core principle ensuring that the state is predictable and easier to manage.

The Solution: Return a New State

To handle state updates correctly, you need to return a new copy of the state each time an action is processed in your reducer. Instead of modifying the existing state, you should create a new array that includes the existing state along with the new values. Here’s how you can do it:

Step-by-Step Guide

Create a New State Array: Use the spread operator (...) to create a new array that combines the existing state and the new value you want to add:

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

No Temporary Variables: Avoid using temporary arrays like test to hold state changes. Instead, operate directly within the reducer.

Return the New State: Always ensure that you're returning the new state from your reducer function. This is essential for NgRx to recognize the updated state and propagate the changes throughout your application.

Conclusion

In conclusion, managing state in NgRx requires adhering to its immutable principles. By understanding why direct modification leads to errors and how to correctly return a new state, you can avoid pitfalls and ensure your application functions as expected. Remember, whenever you need to update your state, think in terms of creating a new state instead of modifying the existing one. Implementing this will not only solve immediate issues but also lead to a more maintainable codebase.

By following these guidelines, you will be better equipped to handle state management in your Angular applications using NgRx effectively. If you ever find yourself facing similar challenges in your coding journey, refer back to this guide as a handy resource!