Web API error on localhost - asp.net-web-api

Question

I am starting developing an Web API using ASP.NET Core MVC. I have been following this Microsoft tutorial: https://learn.microsoft.com/en-us/aspnet/core/tutorials/first-web-api
So far, I have created the code for the following operations:
GET /api/todo
GET /api/todo/{id}
Code:
[Route("api/[controller]")]
public class TodoController : Controller
{
private readonly ITodoRepository _todoRepository;
public TodoController(ITodoRepository todoRepository)
{
_todoRepository = todoRepository;
}
// GET: api/values
[HttpGet]
public IEnumerable<TodoItem> GetAll()
{
return _todoRepository.GetAll();
}
// GET api/values/5
[HttpGet("{id}", Name ="GetTodo")]
public IActionResult GetById(long id)
{
var item = _todoRepository.Find(id);
if(item == null)
{
return NotFound();
}
return new ObjectResult(item);
}
}
However, when I run the Application I am getting the following 500 error:
I understand what the error means, by not why it's happening. Did I miss something?
The interesting part is that I can access the API that was autogenerated when creating the application. But not the new one I added manually.

Answer 1

Change Settings in your Properties -> launchSettings.json File.
{
"$schema": "http://json.schemastore.org/launchsettings.json",
"iisSettings": {
"windowsAuthentication": false,
"anonymousAuthentication": true,
"iisExpress": {
"applicationUrl": "http://localhost:49885",
"sslPort": 44337
}
},
"profiles": {
"IIS Express": {
"commandName": "IISExpress",
"launchBrowser": true,
"launchUrl": "api/todo",
"environmentVariables": {
"ASPNETCORE_ENVIRONMENT": "Development"
}
},
"TodoApi": {
"commandName": "Project",
"launchBrowser": true,
"launchUrl": "api/todo",
"applicationUrl": "https://localhost:5001;http://localhost:5000",
"environmentVariables": {
"ASPNETCORE_ENVIRONMENT": "Development"
}
}
}
}
because by default the "lauchUrl" is set to "api/values" this is the reason why you were getting that error.
Also add this in your Todo Controller, refer the documentation for why this should be added.
namespace TodoApi.Controllers
{
[Route("api/todo")]
[ApiController]
I suggest you to follow the guidelines for creating the app till the last and run it after completion to avoid error.