Compose route template in AspNetCore.Mvc controller

Question

My Controller:

[Route("Categories")]
[ApiController]
public class CategoriesController : ControllerBase
{
    [HttpGet]
    [Route("My")]
    public string[] My()
    {
        return new[]
        {
            "Is the Microwave working?",
            "Where can i pick the washing machine from?",
        };
    }
}

My startup.cs Configure():

app.UseMvc(routes =>
   {
       routes.MapRoute(name: "api", template: "api/v1/{controller}/{action}/");
   });

This works only if I hit url "https://localhost:44325/categories/my"

I need it to have "https://localhost:44325/api/v1/categories/my".

What should I set differently?

I tried something like [Route("[api]/Categories")] attribute on the controller to compose the desired route, but it did not work...

I got:

The following errors occurred with attribute routing information:

Error 1: For action: 'historyAccounts.WebApi.Controllers.CategoriesController.My (historyAccounts.WebApi)' Error: While processing template '[api]/Categories/My', a replacement value for the token 'api' could not be found. Available tokens: 'action, controller'. To use a '[' or ']' as a literal string in a route or within a constraint, use '[[' or ']]' instead.

I want to avoid writing "api/v1" it explicitly in every controller, because when the time comes to change to v2, I will have to update ALL of them ... — cnom
– cnom, Commented Jul 17, 2019 at 11:56

Gaurav Mathur · Accepted Answer · 2019-07-18 11:37:02Z

3

Solution with Attribute Routing

Instead of using MapRoute in Startup create a custom base class -

[Route("api/v1/[controller]/[action]")]
[ApiController]
public class MyControllerBase : ControllerBase { }

Now derive all your controllers from this base class instead of ControllerBase -

public class CategoriesController : MyControllerBase
{
    [HttpGet]
    public string[] My()
    {
        return new[]
        {
            "Is the Microwave working?????",
            "Where can i pick the washing machine from?",
        };
    }
}

This way all your requirements are fulfilled -

Your version information is in one place MyControllerBase
Retained [ApiController] and hence all features it provides

Old Solution

Based on your requirement, if you simply remove Route attribute from your Controllers, it should work the way you want it -

public class CategoriesController : ControllerBase
{
   [HttpGet]
   public string[] My()
   {
       return new[]
       {
           "Is the Microwave working?",
           "Where can i pick the washing machine from?",
       };
   }
}

Keeping you Route map as is -

app.UseMvc(routes =>
{
   routes.MapRoute(name: "api", template: "api/v1/{controller}/{action}/");
});

If you notice, in addition to removing Route attributes I have also removed [ApiController]attribute from class. This attribute force user to use Route instead of Map routing.
Also, Attribute Routing has its own benefits. And as I mentioned earlier "Based on your requirement" if you are not using any of the features of Attributed Routing you can use this approach.

edited Jul 18, 2019 at 11:37

answered Jul 17, 2019 at 12:16

Gaurav Mathur

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4 Comments

cnom Over a year ago

If I remove Route attrs, I get Exception "Action '...My()' does not have an attribute route. Action methods on controllers annotated with ApiControllerAttribute must be attribute routed."

Gaurav Mathur Over a year ago

@cnom I updated my answer, you have to remove [ApiController] attribute as well.

cnom Over a year ago

thank you, but removing [ApiController] attribute is not recommended.

Gaurav Mathur Over a year ago

Updated my answer with better one retaining [ApiController] :)

Edward · Accepted Answer · 2019-07-18 02:46:50Z

2

For MVC Conversation route and Attribute Route, attribute route will override the conversation route.

For the solution from @Gaurav Mathur, all the controller will need to append api/v1 to the request url.

Based on your scenario, if you want to enable version for api, you could try web api version feature instead of configuring the route in the mvc converstaion.

Install package Microsoft.AspNetCore.Mvc.Versioning

Configure in Startup.cs

services.AddApiVersioning(opt => {
    opt.DefaultApiVersion = new ApiVersion(1,0); //this is your version v1
});

ApiController

[Route("api/v{version:apiVersion}/[controller]/[action]")]
[ApiController]
public class ValuesController : ControllerBase
{
    [HttpGet]
    public IActionResult Hello()
    {
        return Ok("Test");
    }
}

Request Url:https://localhost:44369/api/v1/values/hello

answered Jul 18, 2019 at 2:46

Edward

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2 Comments

cnom Over a year ago

but this cannot cover the case where we need to rename "api" part. i.e. /myapi/v1

Edward Over a year ago

@cnom If you prefer chaning other static string, kindly go with the suggestion from Gaurav Mathur

cnom · Accepted Answer · 2019-07-19 08:15:21Z

0

I already accepted a previous answer, but another possible approach is a global constant (i.e. declared on Startup):

public const string BaseUrl = "/api/v1/";

and

[Route(Startup.BaseUrl + "[controller]")]
[ApiController]
public class CategoriesController : ControllerBase

answered Jul 19, 2019 at 8:15

cnom

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