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Cannot get ASP.NET Web API routing to work at all

I am trying to refactor an old setup, the end goal will be that I will have a functional REST API. I am getting rid of an old NuGet service and I sort of have to rebuild everything now. I am trying to set it up using ASP.NET Web API. This will include 60+ routes (like "www.website.com/cars/{id}/engine" "www.website.com/inventory/{id}" etc..)
I have tried attribute routing and conventional routing, and nothing seems to work. I get 404's no matter what I seem to try. I am probably just not doing either of them correctly.
Here is how I am setting up configuration (I am using a self hosting package btw but this is the main configuration point):
public class SomeHostClass
{
public void Configuration(IAppBuilder app)
{
HttpConfiguration config = new HttpConfiguration();
//If I am trying attribute based routing, uncomment this
//config.MapHttpAttributeRoutes();
Register(config.Routes);
// I think I need this at all times?
app.UseWebApi(config);
}
public void Register(HttpRouteCollection routes)
{
// One of many other routes.MapHttpRoute() calls
routes.MapHttpRoute(
name: "Cars",
routeTemplate: "cars/{id}/engine",
defaults: new
{
controller = "CarController",
action = "Get"
},
constraints: null);
}
}
Then here is my Car Controller:
public class CarController : ApiController
{
[HttpGet]
public object Get([FromUri] CarDTO carObject)
{
// Some code calling a private worker method
return WorkerMethod();
}
private object WorkerMethod()
{
// Worker method do stuff, return
}
}
This Get() method is never called and a 404 is returned.
Another note: I have tried using reflection to register all the routes, which slims down the code. I'll debug it and it looks like all the routes have been configured correctly within the HttpConfiguration.routes but I will get 404's still. Even without reflection doing it the way shown above- if I debug and look at the values they all seem correct, but don't work.
Another Note: I should also mention that this is the error I usually get along with the 404.
{"Message":"No HTTP resource was found that matches the request URI 'http://localhost:8000/cars/1/engine'.","MessageDetail":"No type was found that matches the controller named 'CarController'."}
How do I get these routes recognized and stop returning 404's and start returning my data?
If this is a bad way of going about this- what's the best way?

WebAPI MapHttpRoute doesn't work, but AttributeRouting does

I have a case where I can't get a default route to work via Config.Routes.MapHttpRoute(), but if I put the route as a route attribute in the controller it works fine.
Global.asax
protected void Application_Start() {
AreaRegistration.RegisterAllAreas();
WebApiConfig.Register(GlobalConfiguration.Configuration);
FilterConfig.RegisterGlobalFilters(GlobalFilters.Filters);
//RouteConfig.RegisterRoutes(RouteTable.Routes);
//BundleConfig.RegisterBundles(BundleTable.Bundles);
}
(removed last two as they're non-WebAPI requirements (right?) same result even if I leave them in)
WebApiConfig.cs
public static void Register(HttpConfiguration config) {
// Web API configuration and services
// Web API routes
config.MapHttpAttributeRoutes();
config.Routes.MapHttpRoute(
name: "DefaultApi",
routeTemplate: "v1/{controller}/{action}/{id}",
defaults: new { id = RouteParameter.Optional }
);
}
Controller
public class ErrorsController : ApiController
{
[HttpGet]
[Route("v1/Errors/Get")]
public IHttpActionResult Get(int id) {
return Ok();
}
[HttpPost]
[Route("v1/Errors/Submit")]
public IHttpActionResult Submit()
{
// do stuff
return Ok();
}
}
If I have the attribute routes in there, everything works fine. If I don't, I get 404s. For example, the following two report a 404 error:
localhost:myport/v1/Errors/Get?id=5
localhost:myport/v1/Errors/Submit
Yet, if I submit this:
localhost:myport/v1/Errors
I get the following response:
No HTTP resource was found that matches the request URI
'http://localhost:59498/v1/Errors/'.
No type was found that matches the controller named 'v1'.
Obviously my route configuration isn't kicking in, but for the life of my I can't tell why. I even tried changing the route name to Default instead of DefaultApi, thinking that perhaps Default had some internal significance.

"Normal" routing doesn't support this kind of routes with prefix "v1" in it. In a way or another this kind of rounting follows the old MVC routing, where the first part of the address must be the controller; so when you set the address localhost:myport/v1/Errors the system is currently looking for a controller named "v1".
If you want to use a route with a prefix before you have to stick with the attribute routing; that's why it works perfectly with attributes and it doesn't without.
May I suggest you to use a "global" prefix for the v1 thing? That would allow you to avoid repeating the same part of the URL over and over again on different resources. I suggest you to check this article for a couple of implementation details.

WebApi 2 Route Attribute not working unless using parameter

I have a controller List
[Route("api/cache/list")]
[HttpGet]
public IEnumerable<string> List()
{
...
}
But i get a 404 if i try to go to localhost:12121/api/cache/list. My webapi config looks like this:
public static class WebApiConfig
{
public static void Register(HttpConfiguration config)
{
// Web API configuration and services
// Configure Web API to use only bearer token authentication.
//config.SuppressDefaultHostAuthentication();
//config.Filters.Add(new HostAuthenticationFilter(OAuthDefaults.AuthenticationType));
// Web API routes
config.MapHttpAttributeRoutes();
config.Formatters.Remove(config.Formatters.XmlFormatter);
//config.Routes.MapHttpRoute(
// name: "DefaultApi",
// routeTemplate: "api/{controller}/{id}",
// defaults: new { id = RouteParameter.Optional }
//);
}
}
On the other hand if i change that controller to
[Route("api/cache/list/{id}")]
[HttpGet]
public IEnumerable<string> List(int id =0)
{
...
}
It will work. Ive tried doing it without the id as a parameter, still doenst work. What am I doing wrong here?
Extra Info:
I do have a strange setup. My WebApiConfig.cs and global.cs are in a different project. The project which has my controller will then reference the project with the WebApiConfig.cs

Rather than giving the param a default value, try making your id param nullable:
public IEnumerable<string> List(int? id)
Then check for null in code. This also helps differentiate a passed zero from an omitted param value.

I wasnt able to figure out how to fix the problem exactly but I did find a way around my problem.
First I correctly identified that when my routing was in a single assembly the exact same code worked fine. When the routing for my project in a different assembly makes it difficult for config.MapHttpAttributeRoutes(); to correctly identify attribute routes.
On the other hand using a RoutePrefix seemed to fix my issue.
Im not going to set this as my answer because I feel it doesn't truly address the problem, but I felt it would be informational to anyone who comes along this question.

A route named 'MS_attributerouteWebApi' is already in the route collection

I recently added Microsoft.AspNet.WebApi.WebHost to a MVC WebAPI project which would allow me to use the [Route("api/some-action")] attribute on my action. I solved some errors using this article but can't solve the third error below. Added solved errors below to get feedback if I did anything wrong.
First Error: No action was found on the controller 'X' that matches the name 'some-action'
Solution: Added config.MapHttpAttributeRoutes(); to WebApiConfig.cs Register method.
Second Error: System.InvalidOperationException The object has not yet been initialized. Ensure that HttpConfiguration.EnsureInitialized() is called in the application's startup code after all other initialization code.
Solution: Added GlobalConfiguration.Configure(WebApiConfig.Register); to Global.asax.cs Application_Start
Third Error: System.ArgumentException: A route named 'MS_attributerouteWebApi' is already in the route collection. Route names must be unique.
Solution = ?
I've already tried cleaning and deleting all DLLs from bin folder according to this post.

I had a similar problem and it was related to a copy paste error on my part where I added a copy of this line in my WebApiConfig.cs file:
config.MapHttpAttributeRoutes();
make sure you only have one of these.

In the Global.asax, check how many times WebApiConfig.Register function has been called.

Solved! Removed the line WebApiConfig.Register(GlobalConfiguration.Configuration); from Global.asax.cs Application_Start.

I have solved by cleaning the deployment directory before copy the new files. Probably there was some old file that try to register the same root multiple times.

I had the same issue and I discovered that in WebApiConfig.cs
and after I added configuration for API version
I have those two lines
config.MapHttpAttributeRoutes(constraintResolver);
config.MapHttpAttributeRoutes();
I removed the second line
the final code is
public static class WebApiConfig
{
public static void Register(HttpConfiguration config)
{
// Web API routes
var constraintResolver = new DefaultInlineConstraintResolver()
{
ConstraintMap =
{
["apiVersion"] = typeof( ApiVersionRouteConstraint )
}
};
config.MapHttpAttributeRoutes(constraintResolver);
config.AddApiVersioning();
// Web API configuration and services
// Web API routes
// config.MapHttpAttributeRoutes();
config.Routes.MapHttpRoute(
name: "DefaultApi",
routeTemplate: "api/{controller}/{id}",
defaults: new { id = RouteParameter.Optional }
);
}
}

For anybody stumbling across this as I did, this error will happen if you rename the Assembly name (project properties). In my case I was renaming a project, and went into the properties to change the assembly name (which VS2013 won't do for you).
Because the assembly name is different, a Clean or Rebuild will not remove the "old" assembly if it is in the \bin folder. You have to delete the assembly from the \bin folder, then rebuild & run.

Probably you have same register more than one.
Try to delete below codes from Global.asax:
GlobalConfiguration.Configure(WebApiConfig.Register);
RouteConfig.RegisterRoutes(RouteTable.Routes);
and write this ones instead of them :
GlobalConfiguration.Configuration.EnsureInitialized();
BundleConfig.RegisterBundles(BundleTable.Bundles);
I am not sure about reason; but it worked for me in my same case.

I was also experiencing a similar problem (not the MS_attributerouteWebApi route in particular, but a different named route). After verifying only one config.MapHttpAttributeRoutes() existed, began realizing that MapHttpAttributeRoutes will register all project assemblies including externally referenced ones. After finding out that I had a referenced assembly that was registering its own routes, I found a way to exclude or "skip over" routes by overriding the DefaultDirectRouteProvider:
/// <summary>
/// Allows for exclusion from attribute routing of controllers based on name
/// </summary>
public class ExcludeByControllerNameRouteProvider : DefaultDirectRouteProvider {
private string _exclude;
/// <summary>
/// Pass in the string value that you want to exclude, matches on "ControllerType.FullName" and "ControllerType.BaseType.FullName"
/// </summary>
/// <param name="exclude"></param>
public ExcludeByControllerNameRouteProvider(string exclude) {
_exclude = exclude;
}
protected override IReadOnlyList<RouteEntry> GetActionDirectRoutes(
HttpActionDescriptor actionDescriptor,
IReadOnlyList<IDirectRouteFactory> factories,
IInlineConstraintResolver constraintResolver)
{
var actionRoutes = new List<RouteEntry>();
var currentController = actionDescriptor.ControllerDescriptor.ControllerType;
if (!currentController.FullName.Contains(_exclude) && !currentController.BaseType.FullName.Contains(_exclude))
{
var result = base.GetActionDirectRoutes(actionDescriptor, factories, constraintResolver);
actionRoutes = new List<RouteEntry>(result);
}
return actionRoutes.AsReadOnly();
}
}
This allows for you to pass a Controller name or Base Type name in to exclude in your WebApiConfig.cs like:
config.MapHttpAttributeRoutes(new ExcludeByControllerNameRouteProvider("Controller.Name"));
Whether or not directly related, hoping this snippet can help!

I was experiencing the same problem. The solution I found was that I needed visual basic support for mono. When I executed "yum install mono-basic" and restarted my computer the error went away.

In my case error was : "A route named 'MS_attributerouteWebApi' is already in the route collection. Route names must be unique.
Parameter name: name"
Code was:
public static void Register(HttpConfiguration config)
{
// Web API configuration and services
config.MapHttpAttributeRoutes(); // this line had issue
var constraintResolver = new DefaultInlineConstraintResolver();
constraintResolver.ConstraintMap.Add("nonzero", typeof(NonZeroConstraint));
config.MapHttpAttributeRoutes(constraintResolver);
config.Routes.MapHttpRoute(
name: "DefaultApi",
routeTemplate: "api/{controller}/{id}",
defaults: new { id = RouteParameter.Optional }
);
}
Solution :
I just removed - config.MapHttpAttributeRoutes();
line from above method and it got resolved.

Web Api Controller in other project, route attribute not working

I have a solution with two projects. One Web Api bootstap project and the other is a class library.
The class library contains a ApiController with attribute routing.
I add a reference from web api project to the class library and expect this to just work.
The routing in the web api is configured:
config.MapHttpAttributeRoutes();
The controller is simple and looks like:
public class AlertApiController:ApiController
{
[Route("alert")]
[HttpGet]
public HttpResponseMessage GetAlert()
{
return Request.CreateResponse<string>(HttpStatusCode.OK, "alert");
}
}
But I get a 404 when going to the url "/alert".
What am I missing here? Why can't I use this controller? The assembly is definitely loaded so I don't think http://www.strathweb.com/2012/06/using-controllers-from-an-external-assembly-in-asp-net-web-api/ is the answer here.
Any ideas?

Try this. Create a class in your class library project that looks like this,
public static class MyApiConfig {
public static void Register(HttpConfiguration config) {
config.MapHttpAttributeRoutes();
}
}
And wherever you are currently calling the config.MapHttpAttributeRoutes(), instead call MyApiConfig.Register(config).

One possibility is you have 2 routes on different controllers with the same name.
I had 2 controllers both named "UploadController", each in a different namespace and each decorated with a different [RoutePrefix()]. When I tried to access either route I got a 404.
It started working when I changed the name of one of the controllers. It seems the Route Attribute is only keyed on the class name and ignores the namespace.

We were trying to solve a similar problem.
The routes within the external assembly were not registering correctly.
We found one additional detail when trying the solution shown on this page.
The call to the external assembly "MyApiConfig.Register" needed to come before the call to MapHttpRoute
HttpConfiguration config = new HttpConfiguration();
MyExternalNamespace.MyApiConfig.Register(config); //This needs to be before the call to "config.Routes.MapHttpRoute(..."
config.Routes.MapHttpRoute(
name: "DefaultApi",
routeTemplate: "api/{controller}/{id}",
defaults: new { id = RouteParameter.Optional }
);