This app will give you real applications in the use of ASP.NET Core 3 WEB API

You will see the full source code of the demo. You will see how to use:
1. Text Plain in ASP.NET Core 3 Web API
2. Text HTML in ASP.NET Core 3 Web API
3. Use Parameters in ASP.NET Core 3 Web API
4. Use Query String in ASP.NET Core 3 Web API
5. Convert Object to/from JSON in ASP.NET Core 3 Web API
6. Convert List Objects to/from JSON in ASP.NET Core 3 Web API
7. Use POST Method in ASP.NET Core 3 Web API
8. Use PUT Method in ASP.NET Core 3 Web API
9. Use DELETE Method in ASP.NET Core 3 Web API
10. Single File Upload in ASP.NET Core 3 Web API
11. Multiple File Upload in ASP.NET Core 3 Web API
12. Use Middleware in ASP.NET Core 3 Web API
13. Basic Authentication with Middleware in ASP.NET Core 3 Web API
14. Read Data from Database with Entity Framework Core in ASP.NET Core 3 Web API
15. Create Data with Entity Framework Core in ASP.NET Core 3 Web API
16. Update Data with Entity Framework Core in ASP.NET Core 3 Web API
17. Delete Data with Entity Framework Core in ASP.NET Core 3 Web API

You also see the results after the demo with the illustrations.

You can also copy the code in this app and use it on your project.