Url Helpers not working with the api version in URL

[Netclick19]

Hi,
in my API I have some problem with URL helpers with .NET core 3.1.

In startup.cs I set up the api versioning on this way:

services.AddApiVersioning(options =>
            {
                options.DefaultApiVersion = new ApiVersion(1,0);
                options.AssumeDefaultVersionWhenUnspecified = true;
                options.ApiVersionSelector = new CurrentImplementationApiVersionSelector(options);
                options.Conventions.Add(new VersionByNamespaceConvention());
            });

This is my controller.

    [ApiVersion("1.0")]
    [Route("api")]
    //[Route("api/v1/[controller]")]
    [ApiController]
    [Produces("application/json")]
    public class ColorController : Controller

This is my 2 actions.

        [Route("v{version:apiVersion}/[controller]/search", Name = nameof(GetColors))]
        //[Route("get", Name = nameof(GetColor))]
        [HttpGet]
        [ProducesResponseType(StatusCodes.Status200OK)]
        [ProducesResponseType(StatusCodes.Status404NotFound)]
        public IActionResult GetColors()

This is my post action

        [Route("v{version:apiVersion}/[controller]/add", Name = nameof(AddColor))]
        [HttpPost]
        public IActionResult AddColor([FromBody] ColoreEntity objectToAdd)

var url = Url.RouteUrl(nameof(GetColor), new {objectToAdd.idColor});
The url variable is empty.

return CreatedAtRoute(nameof(GetColor), new { idColor = objectToAdd.idColore }, objectToAdd);
this piece of code launch this exception
no route matches the supplied values

It is a bug or probably my mistake?
Thank you for your support.

[commonsensesoftware]

You didn't show the action that you are trying to build a link for, but I imagine that it looks something like this:

[Route("v{version:apiVersion}/[controller]/{idColor}", Name = nameof(GetColor))]
[HttpGet]
[ProducesResponseType(StatusCodes.Status200OK)]
[ProducesResponseType(StatusCodes.Status404NotFound)]
public IActionResult GetColor(string idColor) => Ok();

The reason CreatedAtRoute doesn't work is that you are versioning by URL segment and didn't provide the apiVersion route parameter. I would also recommend that you use CreatedAtAction instead of CreatedAtRoute because the route table is not API Version aware.

The following will get you what you want:

[Route("v{version:apiVersion}/[controller]/add", Name = nameof(AddColor))]
[HttpPost]
public IActionResult AddColor([FromBody] ColoreEntity objectToAdd, ApiVersion apiVersion)
{
    return CreateAtAction(
        nameof(GetColor),
        new { apiVersion = apiVersion.ToString(), idColor = objectToAdd.idColore },
        objectToAdd);
}

I hope that helps.

[Netclick19]

Hi,
thank you for your answer.
I've tried your solution but the error message throw is the same.

This is my GetColor action (sorry, I've pasted the wrong action)

        [Route("v{version:apiVersion}/[controller]/get", Name = nameof(GetColor))]
        [HttpGet]
        [ProducesResponseType(StatusCodes.Status200OK)]
        [ProducesResponseType(StatusCodes.Status400BadRequest)]
        [ProducesResponseType(StatusCodes.Status404NotFound)]
        public IActionResult GetColor([FromQuery] int idColor)

This is my changed post action

        [Route("v{version:apiVersion}/[controller]/add", Name = nameof(AddColor))]
        [HttpPost]
        public IActionResult AddColor([FromBody] ColoreEntity objectToAdd, ApiVersion apiVersion)

       return CreatedAtAction(nameof(GetColor), new { apiVersion = apiVersion.ToString(), idColor = objectToAdd.idColore }, objectToAdd);
        }

Thank you for your support.

[commonsensesoftware]

The changed POST should be something like:

[Route("v{version:apiVersion}/[controller]/add", Name = nameof(AddColor))]
[HttpPost]
public IActionResult AddColor([FromBody] ColoreEntity objectToAdd, ApiVersion apiVersion)
{
    return CreateAtAction(
        nameof(GetColor),
        new { apiVersion = apiVersion.ToString() },
        objectToAdd);
}

It seems odd to me that you'd have a resource ID for a color where the color identifier isn't part of the path. I'm sure you have your reasons. I do not believe that the UrlHelper supports adding query string parameters, which means neither would CreatedAtRoute or CreatedAtAction. As I recall, it only fills in route parameters defined in the route template (which doesn't include query parameters).

The only way around this would be to:

1. Call UrlHelper.Action directly
2. Use the UriBuilder from the generated URI and then add the query string you want
3. Set the response Location header to the generated URL
4. Return status code 201

For reference, here's the source.

I hope that helps.

[Netclick19]

I forgotted the {idColor} parameter to my route.
Now I've changed to
[Route("v{version:apiVersion}/[controller]/get/{idColor}", Name = nameof(GetColor))]
but nothing is changed.

I'will try the solution you suggested.

[commonsensesoftware]

You'll also have to change [FromQuery] int idColor to [FromRoute] int idColor or simply int idColor.

[Netclick19]

I've tried

var url = Url.Action("GetColor", "Color", new { apiVersion = apiVersion.ToString(), idColor = objectToAdd.idColor });
But the returned url is null;

I switch to

        [Route("v{version:apiVersion}/[controller]/getcolor/{idColor}", Name = nameof(GetColor))]
        [HttpGet]
        [ProducesResponseType(StatusCodes.Status200OK)]
        [ProducesResponseType(StatusCodes.Status400BadRequest)]
        [ProducesResponseType(StatusCodes.Status404NotFound)]
        public IActionResult GetColor([FromRoute] int idColor)

but the error throw is the same.

[commonsensesoftware]

sorry ... typo ... use:

var url = Url.Action(
    "GetColor",
    "Color",
    new { version = apiVersion.ToString(), idColor = objectToAdd.idColor });

The route parameter name is version, not apiVersion. Route parameters have the form: <name>[:constraint].

[Netclick19]

Fantastic! Now is working well!!!

I post the final code, if others people will have the same problem.

Controller

    [ApiVersion("1.0")]
    [Route("api/v{version:apiVersion}/[controller]")]
    [ApiController]
    [Produces("application/json")]
    public class ColorController : ControllerBase

Get action

    [Route("getcolor/{idColor}", Name = nameof(GetColor))]
    [HttpGet]
    [ProducesResponseType(StatusCodes.Status200OK)]
    [ProducesResponseType(StatusCodes.Status400BadRequest)]
    [ProducesResponseType(StatusCodes.Status404NotFound)]
    public IActionResult GetColor([FromRoute] int idColor)

Post action

    [Route("add", Name = nameof(AddColor))]
    [HttpPost]
   public IActionResult AddColor([FromBody] ColoreEntity objectToAdd, ApiVersion apiVersion)
   ........
   return CreatedAtAction(nameof(GetColor), new { version = apiVersion.ToString(), idColor = objectToAdd.idColore }, objectToAdd);

Really thank you for your support and for very usefull package!

[commonsensesoftware]

Glad you got it working. ;)

[fourpastmidnight]

@Netclick19 Thanks for posting your solution. You just saved me a boat-load of time!

@commonsensesoftware Is there some way (or, could there be some way—hint, hint, feature request 😉 ), when using URL segment-based versioning, to not to have to add an ApiVersion parameter to HTTP POST methods just so that CreatedAtAction works? If you have the following (and this is very much what I have):

[ApiVersion( "1.0")]
[ApiController]
[Route("api/v{version:apiVersion}/[controller]")]
public sealed class MyController : Controllerbase
{
    [HttpPost]
    [Route("doSomething")
    public async Task<ActionResult> DoSomething(
        [FromBody] doSomethingDto
        /*, ApiVersion apiVersion (why???) */)
    {
        // ... Do some stuff
        return CreatedAtAction(
            nameof(GetSomething),
            new { Id = stuff.Id /*, version = apiVersion.ToString() (why???) */ },
            stuff);
    }

    [HttpGet("{id:Guid}")]
    public async Task<ActionResult> GetSomething(Guid id) { ... }
}

then API Authors would just expect that the RouteAttribute on the controller which contains {version:apiVersion} would be used by the link generators in the URL helpers just as the RouteAttribute on the controller is "inherited" by its action methods. Having to "remember" to add an extra parameter to your POST methods and in the resulting RouteParameters dictionary in URL helpers (such as CreatedAtAction) hardly helps developers fall into the pit of success. Furthermore, this is not documented anywhere except here in this issue that I luckily stumbled across. (Literally—I clicked Issues to see if anyone was experiencing this—and thankfully, someone has only a few days ago, though I'm sorry to say.)

[Netclick19]

I'm agree with your suggestion. A temporary solution could be to hardcode the current apiversion and use it. Not a good solution but...

My problem with adding the apiversion parameter is with Swagger.
I use Swagger to help the users to test my api. But now 4 fields (status, major version, ...) appears as a required parameter.
there is a way to don't add this parameter to Swagger? I know that is a "Swagger problem", but maybe someone of you has a solution.

Thank you.