Url.Link always returns null used within asp..net web api

Question

I want to create some hyperlinks for my DTO`s returned from a REST Api.

The variable url is always null and I do not know why?!

Why is the url not created, what am I still missing?

The name of the route is GetStatusFeedback that's correct and I also use Action and Controller as route parameters + the leadId param!

public class ValuesController : ApiController
{
    [Route("")]
    [HttpGet]
    public IHttpActionResult Get()
    {
        var leadsFromDataBase = new List<Lead> { new Lead { Id = 1 }, new Lead { Id = 2 } };
        var leadDtos = new List<LeadDto>();
        foreach (var lead in leadsFromDataBase)
        {
            var leadDto = new LeadDto();
            string url = Url.Link("GetStatusFeedback", new { LeadId = lead.Id, Action = "Accept", Controller = "values"});
            leadDto.AcceptLink = new Link { Url = url, Verb = "Get" };


            leadDtos.Add(leadDto);
        }
        return Ok(leadDtos);
    }

    [Route("leads/{id:int}/statusfeedback", Name = "GetStatusFeedback")]
    [HttpPost]
    public void Accept(int leadId)
    {

    }

Nope, did not help! If that would have been the problem I would slap the MS dev for ignoring string.equals with ordinalingore case comparer... — Pascal
– Pascal, Commented Aug 9, 2017 at 18:47

Nkosi · Accepted Answer · 2017-08-09 19:00:10Z

6

route parameters need to match the expected parameter in the route template

string url = Url.Link("GetStatusFeedback", new { id = lead.Id });

should match based on the "leads/{id:int}/statusfeedback" route template

also route template placeholders need to match parameter name in the action

[Route("leads/{id:int}/statusfeedback", Name = "GetStatusFeedback")]
[HttpPost]
public void Accept(int id) {

}

Finally you should use proper route names that help describe the route.

edited Aug 9, 2017 at 19:00

answered Aug 9, 2017 at 18:52

Nkosi

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1 Comment

Pascal Over a year ago

argh... I stepped into that old error it happened before :P That was it! To improve the code stability you still can nameof(Accept) the routeName ;-)

ono2012 · Accepted Answer · 2018-09-04 16:43:18Z

It took me a while to get what I needed from the accepted answer (and my mistake differed from the OP), here is a simplified version based on Nkosi's answer and OP's comment:

public class ValuesController : ApiController
{
  [HttpGet]
  public IHttpActionResult Get()
  {
    string url = Url.Link("GetStatusFeedback", new { Id = 1, Action = "Accept", Controller = "values"});
    /*or*/ url = Url.Link(nameof(Accept), new { Id = 1,      Action = "Accept", Controller = "values"});
    //not  url = Url.Link(nameof(Accept), new { LeadId = 1,  Action = "Accept", Controller = "values"});

    return Ok(url);
  }

// Controller we want to get the URL of:
[HttpPost("leads/{id:int}/statusfeedback", Name = "GetStatusFeedback")]
public void Accept(int id) //param name matches the line above {id} (in OP it mismatched)
{

}

Onur Doğan · Accepted Answer · 2024-04-14 20:50:59Z

0

My problem was the router name parameter, I was using the controller name but is the router registered on Program.cs

app.MapControllerRoute(
    name: "default",
    pattern: "{controller=Home}/{action=Index}/{id?}");

for my default was the expected name

edited Apr 14, 2024 at 20:50

Onur Doğan

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answered Apr 10, 2024 at 21:45

Luis Angel Ramirez Hernandez

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