Web API Routing – api/{controller}/{action}/{id} “dysfunctions” api/{controller}/{id}

actionasp.netasp.net-web-apicontrollerrouting

I have the default Route in Global.asax:

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

I wanted to be able to target a specific function, so I created another route:

RouteTable.Routes.MapHttpRoute(
         name: "WithActionApi",
         routeTemplate: "api/{controller}/{action}/{id}",
         defaults: new { id = System.Web.Http.RouteParameter.Optional }
         );

So, in my controller, I have:

    public string Get(int id)
    {
        return "object of id id";
    }        

    [HttpGet]
    public IEnumerable<string> ByCategoryId(int id)
    {
        return new string[] { "byCategory1", "byCategory2" };
    }

Calling .../api/records/bycategoryid/5 will give me what I want.
However, calling .../api/records/1 will give me the error

Multiple actions were found that match the request: …

I understand why that is – the routes just define what URLs are valid, but when it comes to function matching, both Get(int id) and ByCategoryId(int id) match api/{controller}/{id}, which is what confuses the framework.

What do I need to do to get the default API route to work again, and keep the one with {action}? I thought of creating a different controller named RecordByCategoryIdController to match the default API route, for which I would request .../api/recordbycategoryid/5. However, I find that to be a "dirty" (thus unsatisfactory) solution. I've looked for answers on this and no tutorial out there on using a route with {action} even mentions this issue.

Best Answer

The route engine uses the same sequence as you add rules into it. Once it gets the first matched rule, it will stop checking other rules and take this to search for controller and action.

So, you should:

Put your specific rules ahead of your general rules(like default), which means use RouteTable.Routes.MapHttpRoute to map "WithActionApi" first, then "DefaultApi".
Remove the defaults: new { id = System.Web.Http.RouteParameter.Optional } parameter of your "WithActionApi" rule because once id is optional, url like "/api/{part1}/{part2}" will never goes into "DefaultApi".
Add an named action to your "DefaultApi" to tell the route engine which action to enter. Otherwise once you have more than one actions in your controller, the engine won't know which one to use and throws "Multiple actions were found that match the request: ...". Then to make it matches your Get method, use an ActionNameAttribute.

So your route should like this:

// Map this rule first
RouteTable.Routes.MapRoute(
     "WithActionApi",
     "api/{controller}/{action}/{id}"
 );

RouteTable.Routes.MapRoute(
    "DefaultApi",
    "api/{controller}/{id}",
    new { action="DefaultAction", id = System.Web.Http.RouteParameter.Optional }
);

And your controller:

[ActionName("DefaultAction")] //Map Action and you can name your method with any text
public string Get(int id)
{
    return "object of id id";
}        

[HttpGet]
public IEnumerable<string> ByCategoryId(int id)
{
    return new string[] { "byCategory1", "byCategory2" };
}

Related Solutions

C# – Multiple types were found that match the controller named ‘Home’

Here is another scenario where you might confront this error. If you rename your project so that the file name of the assembly changes, it's possible for you to have two versions of your ASP.NET assembly, which will reproduce this error.

The solution is to go to your bin folder and delete the old dlls. (I tried "Rebuild Project", but that didn't delete 'em, so do make sure to check bin to ensure they're gone)

Asp.net-mvc – Returning binary file from controller in ASP.NET Web API

Try using a simple HttpResponseMessage with its Content property set to a StreamContent:

// using System.IO;
// using System.Net.Http;
// using System.Net.Http.Headers;

public HttpResponseMessage Post(string version, string environment,
    string filetype)
{
    var path = @"C:\Temp\test.exe";
    HttpResponseMessage result = new HttpResponseMessage(HttpStatusCode.OK);
    var stream = new FileStream(path, FileMode.Open, FileAccess.Read);
    result.Content = new StreamContent(stream);
    result.Content.Headers.ContentType = 
        new MediaTypeHeaderValue("application/octet-stream");
    return result;
}

A few things to note about the stream used:

You must not call stream.Dispose(), since Web API still needs to be able to access it when it processes the controller method's result to send data back to the client. Therefore, do not use a using (var stream = …) block. Web API will dispose the stream for you.
Make sure that the stream has its current position set to 0 (i.e. the beginning of the stream's data). In the above example, this is a given since you've only just opened the file. However, in other scenarios (such as when you first write some binary data to a MemoryStream), make sure to stream.Seek(0, SeekOrigin.Begin); or set stream.Position = 0;
With file streams, explicitly specifying FileAccess.Read permission can help prevent access rights issues on web servers; IIS application pool accounts are often given only read / list / execute access rights to the wwwroot.

Best Answer

Related Solutions

C# – Multiple types were found that match the controller named ‘Home’

Asp.net-mvc – Returning binary file from controller in ASP.NET Web API

Related Topic