Скачать или смотреть How to Set Select Options Based on Another Select Element's Value in Angular

Discover how to dynamically filter options in Angular based on the user's selection in another dropdown list. Master the use of ngModel and reactive forms for better data handling.
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How to Set Select Options Based on Another Select Element's Value in Angular

In many web applications, you may want to filter options in a dropdown based on a user's selection in another dropdown. This is a common use case in forms where the value selected in one select element determines the available options in another. For example, if you have a dropdown for classes and another for students, selecting a class should only show the students of that class.

This guide will guide you through the solution for implementing such functionality in Angular, keeping it simple and straightforward.

The Scenario

Imagine you have two select elements in your Angular application. The first dropdown allows you to select a class, while the second dropdown lists students. You want to ensure that when a class is selected, only the students from that class are displayed. Here’s the current code structure:

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

As such, we want to ensure that the students array changes dynamically based on the selectedClass.

Solution: Using ngModelChange

Step 1: Track Changes with ngModelChange

To achieve the desired functionality, we can track changes in the selectedClass using the (ngModelChange) event. This allows us to call a function whenever the user selects a different class.

Here’s how you can modify your select element for classes:

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

Step 2: Implement classChanged Function

Next, you need to implement the classChanged function in your component. This function will update the students array based on the newly selected class.

Here’s what the implementation might look like:

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

For the simplicity of this example, you may have a method like getStudentsByClass, which fetches the list of students associated with the selected class.

Step 3: Update the Students Array

Define your logic that would filter or fetch the appropriate students based on the selected class. Here’s an example logic:

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

Conclusion

By utilizing Angular's ngModelChange and a straightforward function like classChanged, you can effectively filter a second dropdown based on the selected option from the first dropdown. This implementation not only simplifies user experience but also ensures your forms are interactive and functional.

By following this approach, your Angular application will be more responsive to user input, enhancing its usability significantly!

Now you're all set to implement this in your project! Happy coding!