How to Fix the 404 Error in ASP.NET Core and Angular Get Method

Troubleshoot the 404 error in your ASP.NET Core API's Get method with this detailed guide. Learn how to adjust your API routing and service calls in Angular for a smooth experience.
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How to Fix the 404 Error in ASP.NET Core and Angular Get Method

If you've encountered a frustrating 404 error while working with the Get User method in your ASP.NET Core API integrated with an Angular frontend, you're not alone. This issue typically arises when the routing to the API method isn't configured correctly, leading to failed requests and unexpected errors. In this guide, we'll walk you through the problem and provide a clear solution to get your API working as intended.

Understanding the Problem

The user faced a situation where the GetUser method in their API was returning a 404 error, meaning that the requested resource could not be found. Their existing API controller code for the GetUser method looked like this:

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

Despite the GetAllUsers method working fine, the GetUser method was failing, and the user had already tried various routes without success.

Analyzing the Root Cause

Routing Issues

In ASP.NET Core, the way routes are defined in your controller can heavily affect how requests are handled. If the route isn't set correctly or if the API is expecting a different parameter format, it can easily lead to a 404 error.

Inconsistent API Call

The API call from Angular consisted of a query parameter (?id=) instead of directly appending the ID to the URL, which is contrary to how the routing is configured in the API.

Solution Steps

To resolve this 404 error, you can follow these solution steps:

Step 1: Update the Action Attribute Routing

Modify your GetUser method routing by making the following change:

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

This change helps ensure that the routing is correctly recognized at the API level and the expected endpoint becomes clearer.

Step 2: Fix the Angular Service Call

Next, you will need to update the service call in your Angular application. Change the API call to properly include the ID without the query parameter:

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

By appending the id directly to the URL, you align it with the expected API routing structure, preventing the 404 error.

Testing Your Changes

Once you have made these changes:

Restart your ASP.NET Core server to ensure the new routing is applied.

Test your Angular service method again by calling Load(id) with a valid user ID.

Check if the response returns the user data as expected.

Conclusion

By properly configuring your API and ensuring that the service call from your Angular application aligns with your backend routing, you should be able to resolve the 404 error that was preventing the retrieval of user data.

Remember, proper routing and consistency in URL structures are crucial for seamless communication between your frontend and backend. If you encounter similar issues in the future, reviewing your routes and API calls should be your first step to troubleshoot effectively.

Feel free to leave any comments or questions below if you need further assistance!

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