A Better Way to Update Single Items in Angular's ngFor List

Описание: Discover a more efficient method for updating single items in Angular's ngFor list using `forkJoin` and `switchMap` for cleaner code and improved performance.
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A Better Way to Update Single Items in Angular's ngFor List

Angular is a powerful framework that allows developers to build dynamic web applications with ease. However, just like any other technology, there's always room for improvement. If you've been using the ngFor directive to display a list of items, you might be wondering if there are better ways to update individual items without affecting the others. Let’s dive into the problem and explore a more efficient solution!

The Problem: Updating Items in an ngFor Loop

In your current implementation, you have an ngFor loop that displays a list of deals. You invoke a method to get user data based on the owner ID, but this method's implementation can lead to challenges like:

Inefficient Calls: Calling a method repeatedly for each item in the list can lead to excessive database calls, especially if the list is large.

Shared State Issue: If the last value fetched is used to update multiple items, they all end up with the same value. This is suboptimal and can confuse users.

Current Implementation Snippet

Here's a quick look at your current setup:

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

This constructs a new observable for each dealer, which can lead to inefficiency.

The Better Solution: Using forkJoin and switchMap

To enhance performance and ensure that individual items within your list are updated correctly, you can utilize forkJoin and switchMap from RxJS. This approach allows you to combine multiple observables and handle them in parallel, rather than sequentially.

Step-by-Step Implementation

Modify Your Data Fetching Logic: Use forkJoin to gather data for all deals in one go.

Incorporate switchMap: Replace your existing calls with switchMap, ensuring that you handle each deal's observable without creating redundant data.

Map the Results: Merge the deal and owner data into a single result for each deal, updating each deal with the correct user information.

Example Implementation

Here’s how your updated data-fetching function would look:

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

Benefits of This Approach

Reduced Database Calls: By fetching user data for all deals in parallel, you drastically reduce the number of calls your application makes, which can lead to performance improvements.

Accurate Data Handling: Each deal retains its unique user information without interference from other items, preventing issues where all items show the same user.

Cleaner Code: Using forkJoin and switchMap reduces complexity and makes your codebase cleaner and easier to maintain.

Conclusion

Improving how we handle updates in Angular's ngFor loop not only enhances performance but also ensures that the data presented to users is accurate and meaningful. Switching to a solution using forkJoin and switchMap addresses common pitfalls associated with repeated calls and shared state issues. Remember, refactoring is key in software development – continually look for ways to optimize your codebase! Happy coding!