Скачать или смотреть How to Properly Use Dynamic Variables in ngFor with Angular 11

Learn how to embed dynamic variables in Angular 11's `ngFor` without syntax errors using effective methods and best practices.
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Embedding Dynamic Variables in ngFor in Angular 11

When working with Angular, especially at version 11, developers often encounter some syntax hurdles. One common issue faced by many is how to embed dynamic variables using the *ngFor directive. If you've stumbled upon a syntax error while doing so, you're not alone! In this guide, we will resolve these issues and provide clear guidance on how to correctly use dynamic variables in your Angular applications.

Understanding the Problem

Let's say you have a table where you want to display and edit incidents retrieved from a list. You might start with an ngFor loop to iterate over these incidents, expecting to dynamically pass the incident id to a function when a button is clicked. Here’s a snippet illustrating the problem:

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

In this code snippet, you might notice that when you try to call editRecord({{incident.id}}), you run into a syntax error. But why does this happen?

The Core Issue

The error stems from the way Angular handles method calls within event bindings like (click). In Angular, when you're making a call to a method, it expects either a variable, a method reference, or executable code. By using the interpolation syntax {{ }} inside the method call, you're breaking the expected format, leading to the error.

Solution: Correcting the Click Binding

The best solution to this problem is simple and straightforward. You do not need to embed the double curly braces {{ }} at all. Instead, you can directly reference the variable. Here's how you can modify the button click:

Updated Button Code

Change your button code to look like this:

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

Explanation of the Fix

Direct Variable Reference: The key change is to simply pass incident.id without the curly braces. This tells Angular to recognize incident.id as a variable that should be evaluated rather than treated as a string.

Maintain Readability: The use of {{ incident.id }} in your button text still works perfectly, so you maintain a nice, user-friendly display.

Summary

By following these simple guidelines, you can effectively work with dynamic variables in your Angular applications. Remember:

Use direct variable references without {{ }} in method calls for bindings.

Retain your template’s functionality and readability by continuing to use interpolation where it is applicable.

These small adjustments can help you navigate Angular's syntax and make your development process smoother. If you apply these practices consistently, you’ll reduce errors and build more robust applications.

Happy coding in Angular!