Скачать или смотреть How to Get the Type of Error of a Validator in Angular Forms

Learn how to identify and handle validation errors in Angular forms by retrieving specific error types for custom validators.
---
This video is based on the question https://stackoverflow.com/q/67906395/ asked by the user 'Luca' ( https://stackoverflow.com/u/14676632/ ) and on the answer https://stackoverflow.com/a/67906751/ provided by the user 'Wahib Kerkeni' ( https://stackoverflow.com/u/4854087/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

Visit these links for original content and any more details, such as alternate solutions, latest updates/developments on topic, comments, revision history etc. For example, the original title of the Question was: how to get the type of error of a Validator

Also, Content (except music) licensed under CC BY-SA https://meta.stackexchange.com/help/l...
The original Question post is licensed under the 'CC BY-SA 4.0' ( https://creativecommons.org/licenses/... ) license, and the original Answer post is licensed under the 'CC BY-SA 4.0' ( https://creativecommons.org/licenses/... ) license.

If anything seems off to you, please feel free to write me at vlogize [AT] gmail [DOT] com.
---
Understanding Form Validation in Angular: Retrieving Error Types

Form validation is a critical feature in web applications that enhances user experience and data integrity. In Angular, it's essential to know how to retrieve specific error types during form submission, especially when using custom validators. In this guide, we’ll discuss how to capture and manage validation errors effectively and ensure your users receive helpful feedback while filling out forms.

The Problem: Identifying Validation Errors

Imagine you have a form input—such as a password field—that needs to meet certain criteria (like a minimum length and the inclusion of special characters). When your users submit the form, it’s important to provide clear feedback regarding any errors. However, it may not be immediately clear how to retrieve the specific type of error that occurred during validation.

Example Input Form

You have a simple form defined as follows:

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

When the user submits the form, you want to specify what went wrong, such as:

The password is too short (less than 8 characters).

The password does not contain any special characters.

The Solution: Using hasError() and Accessing Control Errors

Using hasError() Method

One of the most straightforward methods to check for validation errors in Angular is to use the hasError() method. Here’s how you can implement this in your onSubmit() function.

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

Explained:

Check if the form is invalid: Before checking for errors, ensure that the form is invalid.

Access the password control: Use this.formGroup.get('password') to access the password field's control.

Identify specific errors: Use hasError('errorType') to determine whether a specific validation error occurred.

Accessing Control Errors Directly

Another approach is to directly access the errors of the form control. This method allows you to tailor messages based on the exact validation issue encountered.

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

Explained:

Check for Invalid Form: As before, ensure the form is invalid before proceeding.

Access Control Errors: Use this.formGroup.controls.password.errors to access the errors directly associated with the password field.

Use Optional Chaining: Conditional access with ?. helps to avoid errors when no error exists; it safely returns undefined if not found.

Conclusion

By implementing either the hasError() method or accessing control errors directly, you can efficiently identify and communicate the specific validation issues your users encounter. This not only enhances user experience but also ensures that your forms collect valid data.

As the web continues to evolve, mastering form validation will empower you to create more robust applications. Embrace these techniques and make your Angular forms more user-friendly today!