How do I use ASP.NET Web API Attribute Routing with a complex object parameter?

Question

I have a Web API action that looks like the following:

[HttpGet]
[Route("api/query/hello/{query}")]
public HttpResponseMessage Hello([FromUri]Query query)
{
    return null;
}

where the Query class has a public string property named QueryText. When I hit the following URL, I get a 404 error:

/api/query/hello?QueryText=bacon

This worked before I started using Attribute Routing. If I have no parameters or primitive type parameters, I can get Attribute Routing to work. But with a complex parameter, I get 404s. How does Attribute Routing work with complex action parameters? Is it compatible with the FromUri attribute?

Answer 1

The solution here was that the {query} token in the Route definition was superfluous. Removing it, as follows, fixed the issue:

[Route("api/query/hello")]

Answer 2

The [FromUri] attribute will be needed because you're reading from the URL. Your route should look something like:

public HttpResponseMessage Hello([FromUri]Query query)
{
    //Implement whatever
    return null;
}

/api/{Controller Name}/hello?QueryText=bacon

Should then work correctly.

The model binder will take whatever query parameters you provided then try to bind whatever is inside that Query object. I'd worry about the Route Attribute after you've got it working first.