228
votes

I need to implement the following WebAPI method:

/api/books?author=XXX&title=XXX&isbn=XXX&somethingelse=XXX&date=XXX

All of the query string parameters can be null. That is, the caller can specify from 0 to all of the 5 parameters.

In MVC4 beta I used to do the following:

public class BooksController : ApiController
{
    // GET /api/books?author=tolk&title=lord&isbn=91&somethingelse=ABC&date=1970-01-01
    public string GetFindBooks(string author, string title, string isbn, string somethingelse, DateTime? date) 
    {
        // ...
    }
}

MVC4 RC doesn't behave like this anymore. If I specify fewer than 5 parameters, it replies with a 404 saying:

No action was found on the controller 'Books' that matches the request.

What is the correct method signature to make it behave like it used to, without having to specify the optional parameter in the URL routing?

5
put [httpget] on action.user960567
If I set all of the parameters the method gets called; furthermore it starts with Get so it is automatically bound with the HTTP GET method...frapontillo
Yes. I know how it works. I just can't get it to work under THIS particular circumstance.frapontillo
How did this even compile? string? is not a valid type. You can't declare string as a nullable type since it is a reference type.EkoostikMartin

5 Answers

321
votes

This issue has been fixed in the regular release of MVC4. Now you can do:

public string GetFindBooks(string author="", string title="", string isbn="", string  somethingelse="", DateTime? date= null) 
{
    // ...
}

and everything will work out of the box.

89
votes

It's possible to pass multiple parameters as a single model as vijay suggested. This works for GET when you use the FromUri parameter attribute. This tells WebAPI to fill the model from the query parameters.

The result is a cleaner controller action with just a single parameter. For more information see: http://www.asp.net/web-api/overview/formats-and-model-binding/parameter-binding-in-aspnet-web-api

public class BooksController : ApiController
  {
    // GET /api/books?author=tolk&title=lord&isbn=91&somethingelse=ABC&date=1970-01-01
    public string GetFindBooks([FromUri]BookQuery query)
    {
      // ...
    }
  }

  public class BookQuery
  {
    public string Author { get; set; }
    public string Title { get; set; }
    public string ISBN { get; set; }
    public string SomethingElse { get; set; }
    public DateTime? Date { get; set; }
  }

It even supports multiple parameters, as long as the properties don't conflict.

// GET /api/books?author=tolk&title=lord&isbn=91&somethingelse=ABC&date=1970-01-01
public string GetFindBooks([FromUri]BookQuery query, [FromUri]Paging paging)
{
  // ...
}

public class Paging
{
  public string Sort { get; set; }
  public int Skip { get; set; }
  public int Take { get; set; }
}

Update:
In order to ensure the values are optional make sure to use reference types or nullables (ex. int?) for the models properties.

75
votes

Use initial default values for all parameters like below

public string GetFindBooks(string author="", string title="", string isbn="", string  somethingelse="", DateTime? date= null) 
{
    // ...
}
1
votes

if you want to pass multiple parameters then you can create model instead of passing multiple parameters.

in case you dont want to pass any parameter then you can skip as well in it, and your code will look neat and clean.

1
votes

Default values cannot be supplied for parameters that are not declared 'optional'

 Function GetFindBooks(id As Integer, ByVal pid As Integer, Optional sort As String = "DESC", Optional limit As Integer = 99)

In your WebApiConfig

 config.Routes.MapHttpRoute( _
          name:="books", _
          routeTemplate:="api/{controller}/{action}/{id}/{pid}/{sort}/{limit}", _
          defaults:=New With {.id = RouteParameter.Optional, .pid = RouteParameter.Optional, .sort = UrlParameter.Optional, .limit = UrlParameter.Optional} _
      )