Multiple actions were found that match the request Web API?

Question

I am using web API and i am new in this. I am stuck in a routing problem. I have a controller with following actions :

    // GET api/Ceremony     public IEnumerable<Ceremony> GetCeremonies()     {         return db.Ceremonies.AsEnumerable();     }      // GET api/Ceremony/5     public Ceremony GetCeremony(int id)     {         Ceremony ceremony = db.Ceremonies.Find(id);         return ceremony;     }      public IEnumerable<Ceremony> GetFilteredCeremonies(Search filter)     {         return filter.Ceremonies();     } 

The problem occure when i added the action GetFilteredCeremonies to my controller. After adding this when i make an ajax call to GetCeremonies action then it return an Exception with following message :

"Message":"An error has occurred.","ExceptionMessage":"Multiple actions were   found that match the request 

FYI: The parameter Search is the Model class which contains properties and a function name Ceremonies.

EDIT

Route:

config.Routes.MapHttpRoute(                 name: "DefaultApi",                 routeTemplate: "api/{controller}/{id}",                 defaults: new { id = RouteParameter.Optional }             ); 

Answer 1

The problem here is your 2 Get methods will resolve to api/Ceremony and MVC does not allow parameter overloading. A quick workaround (not necessarily the preferred approach) for this sort of problem is to make your id parameter nullable e.g.

// GET api/Ceremony public IEnumerable<Ceremony> GetCeremonies(int? id) {     if (id.HasValue)     {         Ceremony ceremony = db.Ceremonies.Find(id);         return ceremony;     }     else     {         return db.Ceremonies.AsEnumerable();     } } 

However, you would then be returning a list of ceremonies when with 1 item when your trying to query for a single ceremony - if you could live with that then it may be the solution for you.

The recommended solution is to map your paths appropriately to the correct actions e.g.

context.Routes.MapHttpRoute(     name: "GetAllCeremonies",     routeTemplate: "api/{controller}",     defaults: new { action = "GetCeremonies" } );  context.Routes.MapHttpRoute(     name: "GetSingleCeremony",     routeTemplate: "api/{controller}/{id}",     defaults: new { action = "GetCeremony", id = UrlParameter.Optional } ); 

Answer 2

If you're not requirement bound to use REST services that use api/{controller}/{id} route and attempt to resolve action based on method GET/POST/DELETE/PUT, you can modify your route to classic MVC route to api/{controller}/{action}/{id} and it will solve your problems.