How to Handle Server-Side Error Messages in a .NET Core 5.0 and Angular 11 Contact Form

Learn how to effectively render server-side validation errors in your Angular 11 application using .NET Core 5.0 backend. Ensure a seamless user experience by handling form submission errors properly.
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Handling Server-Side Error Messages in a .NET Core 5.0 and Angular 11 Contact Form

Creating a contact form can often feel like an easy task, but the actual implementation can become complex, especially when handling errors from the server. In this guide, we are going to address a common issue faced by developers: how to properly render server-side validation errors in your Angular 11 application using a .NET Core 5.0 backend.

The Problem

You have a contact form deployed in Angular 11 that sends data to a .NET Core 5.0 backend service. The backend enforces validation rules on the model using attributes like Required and StringLength. However, you want to ensure that if a user submits an empty form or if any other validation issue occurs, the corresponding error messages are displayed on the client-side. Currently, you're facing challenges in capturing these server-side errors and delivering them to your Angular application.

The Solution

Step 1: Implement Form Validation on the Client-Side

Before diving into server-side error handling, it’s essential to ensure that the form is validated on the client-side. This can prevent unnecessary requests to your server with invalid data.

Disable the submit button when Angular validators determine that the form is invalid. This approach ensures that users cannot submit the form until all required fields are correctly filled.

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Step 2: Capture Server-Side Errors

When you send the data from the form to the backend, it's important to capture any errors returned by the server. Here’s how you can update your API call:

In your API call function, instead of assigning the contactForm.errors to errorMessage, directly assign the error received from the server. This ensures that all relevant error messages are properly captured and can be displayed to the user.

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Step 3: Displaying Error Messages

Finally, display the error messages within your component template. You can use something similar to the following code:

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Summary

Handling server-side errors effectively can significantly enhance the user experience in your Angular application. By implementing form validation, capturing server responses, and dynamically displaying error messages, you create a robust mechanism for guiding users through the form submission process.

Key Takeaways

Use Angular validators to improve the client-side validation.

Capture error messages returned from the server and display them clearly to users.

Always provide clear and concise feedback to improve user experience.

By following these steps, you'll ensure that your users receive valuable feedback, making your application more intuitive and user-friendly.

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