Question

I have a Action method like this

[HttpPost]
public ActionResult DoSearchRequestOperation(SearchRequestModelDto data)
{
     //..
}

when I us this url string http://localhost:9124/Search/SearchRequest?searchRequestFor=0 , it works. but when i use the url http://localhost:9124/Search/SearchRequest?searchRequestFor= , it is throwing this exception

System.ArgumentException: The parameters dictionary contains a null
entry for parameter ‘searchRequestFor’ of non-nullable type
‘xxxx.Shared.Dto.Process.Search.SearchRequestFor’ for method
‘System.Web.Mvc.ActionResult
SearchRequest(xxxx.Shared.Dto.Process.Search.SearchRequestFor)’ in
‘xxxx.WebServer.UI.Controllers.SearchController

if the user is giving second url it should take the value 0.

I tried changing the maproute like below, but that also is not working.

  routes.MapRoute(
            "Default1", // Route name
            "{controller}/{action}/{id}", // URL with parameters
            new { controller = "Home", action = "Dashboard", id = 0 } 
        );

Here is the SearchRequestModelDto class

[DataContract]
public class SearchRequestModelDto : UIBoundDto
{
    public SearchRequestModelDto()
    {
        Criteria = new SearchRequestCriteriaDto();
        SearchResult = new SearchRequestResultDto();
    }

    [DataMember]
    public SearchRequestCriteriaDto Criteria { get; set; }

    [DataMember]
    public SearchRequestResultDto SearchResult { get; set; }
}

Answer 1

You could make the SearchRequestFor property on your SearchRequestModelDto view model a nullable integer if you want to be able to send null values in the query string:

public int? SearchRequestFor { get; set; }

The fact that you have set id=0 in your route has no influence on query string parameters. They are not governed by routes so you will have to either write a custom model binder or use a nullable integer on the model. The latter is preferred.