Скачать или смотреть Resolving the CORS Issue in Your Angular and ASP.NET Core Application on macOS

Discover how to fix the `CORS` issue between your Angular app and ASP.NET Core backend on macOS. Learn the steps to configure your applications correctly for seamless communication.
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Fixing CORS Issues in Angular and ASP.NET Core on macOS

As web applications evolve, developers often encounter challenges like Cross-Origin Resource Sharing (CORS) restrictions. If you're running an Angular application alongside an ASP.NET Core backend on your local machine (macOS), you may have faced the frustrating CORS error: "Origin https://localhost:44419 is not allowed by Access-Control-Allow-Origin." In this post, we will break down why this happens and how you can resolve it effectively.

Understanding the CORS Issue

CORS is a security feature implemented by browsers to prevent malicious websites from interacting with your API without permission. When both your Angular app and ASP.NET Core app are running on different ports (even if they're on localhost), the browser considers them different origins. This is where the CORS issue arises.

Key Questions:

Why am I encountering CORS issues when both my APIs are running on localhost?

How can I configure my applications properly to avoid these restrictions?

Analyzing the Code

Current Setup

From the code you've shared, here's how your applications are currently configured:

Angular App: Running on http://localhost:44419

ASP.NET Core App: Running on http://localhost:52703

Your ASP.NET Core app includes a CORS policy configuration, but during your attempts to access this API from your Angular app, you still faced CORS violations.

ASP.NET Core Configuration

Here’s a snippet of your CORS configuration:

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

Angular Proxy Configuration

Your Angular proxy.conf.js file is vital for rerouting API requests during development. Here’s the essential part of that config:

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

This is where the issue was hidden. Let’s find out why.

Fixing the CORS Issue

After careful examination of your setup, you discovered the problem was with the URL specified in your proxy.conf.js file. It was initially set to an http URL while your ASP.NET Core app was running under HTTPS, leading to the CORS errors since they were initiating connections over different protocols.

Steps to Fix:

Update the Target URL: Change the target URL to ensure both apps communicate over HTTPS. Here is the corrected line:

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

Remove Unnecessary CORS Settings: Once the URLs match and are compliant over HTTPS, you may find that the CORS policy settings in your ASP.NET Core app may no longer be necessary. The issues should resolve themselves because both applications are running from the same origin.

Conclusion

CORS issues can be a headache for developers, especially when working with multiple frameworks and local setups. However, by ensuring that your proxy configuration aligns with your application's protocol (HTTP vs. HTTPS) and maintaining consistent origins, you can eliminate these problems efficiently.

Final Thoughts

If you are encountering CORS issues while developing with Angular and ASP.NET Core, check your proxy configuration first. Ensuring that both applications run under the same protocol simplifies networking issues significantly. Test your setup after making changes, and you should be back on track with seamless communication between your Angular app and ASP.NET backend.

With this guide, you now have a clear path to tackle the CORS issue head-on. Happy coding!