Optional query string parameters in ASP NET Web API

Question

I need to implement the following WebAPI method    api books author XXX amp title XXX amp isbn XXX amp somethingelse XXX amp 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 amp title lord amp isbn 91 amp somethingelse ABC amp 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

User · Answer

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} _
      )

User · Answer

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 amp title lord amp isbn 91 amp somethingelse ABC amp 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 amp title lord amp isbn 91 amp somethingelse ABC amp 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

User · Answer

Use initial default values for all parameters like below  public string GetFindBooks string author     string title     string isbn     string  somethingelse     DateTime  date  null

User · Answer

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

User · Answer

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

[c#] Optional query string parameters in ASP.NET Web API

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