Resolving Angular Code Compatibility Issues in Version 11.2.12

Discover how to fix your Angular code that is not running in version 11.2.12, by understanding TypeScript requirements and template type checking.
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This video is based on the question https://stackoverflow.com/q/67430635/ asked by the user 'Hari Harkala' ( https://stackoverflow.com/u/5939189/ ) and on the answer https://stackoverflow.com/a/67431157/ provided by the user 'Devang Patel' ( https://stackoverflow.com/u/10755112/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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Resolving Angular Code Compatibility Issues in Version 11.2.12

Developing with Angular can sometimes lead to frustrating moments, especially when updating to newer versions. If you’re running into issues with your Angular application like some users experiencing problems with compatibility in Angular version 11.2.12, fret not! In this post, we’ll dive into the core problem and present a comprehensive solution.

The Problem

Imagine you have a working Angular application coded with version 6.0.3. Now, you’ve decided to upgrade to Angular 11.2.12, but your code no longer runs. Specifically, you're encountering TypeScript errors, indicating that properties like id and name do not exist on type Object. Here’s a quick overview of the error you may see:

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

A Peek at Your Code

You’re likely working with a component that defines a list of products, structured like this:

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

Your template (HTML) is similarly structured, using ngFor to iterate over the items in the products array.

Understanding the Root Cause

With the upgrade to Angular 9.x and beyond, Angular introduced Template type checking, which adds more stringent checks on the types being used within your templates. This means that the properties of your objects need to be well-defined for Angular to know how to render them correctly.

The key problem here is that specifying products: Object[]; does not allow TypeScript to understand the structure of the objects contained within the products array.

The Solution: Define Product Types Explicitly

To resolve the issues you’re encountering, the simplest fix is to clearly define the structure of the products array. Instead of using a loose Object type, you should specify what each product object should look like:

Step 1: Update Product Type Definition

Change the type definition of the products array:

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

Step 2: Full Code Example

Here is how your ProductComponent should now look:

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

Step 3: Verify HTML Template

Don't forget your HTML (template) should remain the same and will now work without issues:

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

Conclusion

By defining the structure of your products array explicitly, you've resolved the compatibility issues that arose after upgrading to Angular 11.2.12. It’s always a good practice to adhere to strict typing in TypeScript, as this not only reduces errors during development but also enhances code clarity and maintainability.

Updating Angular can be challenging, but with the right knowledge and approach, you can navigate these hurdles efficiently. Happy coding!

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