What route do I add to map to an API controller?

Question

I've added an ApiController to my asp.net core 2.2 app and the async calls from the UI are not matching.

Here are my routes in Startup.cs.

app.UseMvc(config =>
{
    config.MapRoute(
        "Api",
        "api/{controller}/{action}/{id?}"
    );

    config.MapRoute(
        "Default", 
        "{controller=App}/{action=Index}/{id?}"
    );
});

Here is one of the javascript functions that's making various GET requests to the API controller.

function clearAllFilters() {
  $.get({
    url: "/api/GridFilter/ClearAllFilters",
    contentType: "application/json; charset=utf-8",
    dataType: "json",
    success: function () {
        console.log('filters cleared');
    }
  });
}

Here is the API controller:

[Route("api/[controller]")]
[ApiController]
public class GridFilterController : ControllerBase
{
    private static readonly string[] FilterFields = {
        // Bunch of strings, omitted for brevity
    };

    [HttpGet]
    public IActionResult ClearAllFilters()
    {
        foreach (string column in FilterFields)
        {
            if (HttpContext.Session.TryGetValue(column, out byte[] savedJson))
            {
                HttpContext.Session.Remove(column);
            }
        }
        return Ok(true);
    }

Why doesn't asp.net match this? My url is /api/controller/action which seems like it matches the first route that's mapped in startup.

Kirk Larkin Kirk Larkin · Accepted Answer · 2019-09-28T16:08:03

You're mixing Conventional Routing and Attribute Routing:

Actions are either conventionally routed or attribute routed. Placing a route on the controller or the action makes it attribute routed. Actions that define attribute routes cannot be reached through the conventional routes and vice-versa. Any route attribute on the controller makes all actions in the controller attribute routed.

The following call from your example configures a conventional routing template:

config.MapRoute("Api","api/{controller}/{action}/{id?}");

However, you've configured GridFilterController to use attribute routing by using a routing attribute ([Route(...)]):

[Route("api/[controller]")]
[ApiController]
public class GridFilterController : ControllerBase

To access the ClearAllFilters action from /api/GridFilter/ClearAllFilters, you have two general options:

Change the attribute routing template to:
```
[Route("api/[controller]/[action]")]
```
This means the name of the action will be included as part of the route, which is similar to the conventional routing template you've set up.
Remove the [Route(...)] attribute altogether. However, this isn't ideal, as you'll also have to remove the [ApiController] attribute because that requires attribute routing.

What route do I add to map to an API controller?

1 Answers