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Learn how to properly update objects in an observable array in Angular without running into immutable property errors.
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How to Update Observable Array of Objects in Angular Without Errors

When working with Angular and observables, you might encounter a common issue when trying to update an object within an observable array. Specifically, if you attempt to modify an object property directly, you may see an error message similar to the following:

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

This error arises because objects in observable arrays are immutable by design, which means you cannot change their properties directly. In this guide, we'll explore how to tackle this issue and effectively update an observable array of objects in Angular.

Understanding the Problem

In the given code example, you define an interface called User with several properties such as id, name, lastname, email, address, and password. The observable array allUsers initializes an observable of an array of User objects.

Here's a simplified version of the initial code structure:

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

When you attempt to update the name, lastname, and other properties directly within the map() function, Angular throws a TypeError because those objects cannot be modified directly. To resolve this, you need to return a new object with the updated properties instead.

Solution: Returning New Objects

Here's how you can solve the problem by creating new instances of the User object with the updated properties:

Step-by-step Instructions

Use the Spread Operator: You can create a new object by spreading the old object's properties and then updating the desired ones.

Update Method: Modify the update method to ensure it returns a new object rather than changing the existing one. Here’s the revised code:

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

Key Points to Remember

Immutability: When modifying objects in an observable array, always return a new instance of the object rather than modifying the existing one.

Spread Operator (...): This operator is a convenient way to copy properties from the existing object while overriding only the necessary ones.

Efficient Data Handling: This strategy not only fixes your TypeError but also promotes better data handling practices in your Angular applications, avoiding side effects.

Conclusion

In summary, updating objects in an observable array in Angular requires you to adhere to immutable principles. By returning a new object instead of altering the existing one, you can effectively update the array without running into errors.

Follow these best practices to keep your Angular applications running smoothly and efficiently.

If you have further questions or need clarification on this topic, feel free to comment below!