Develop Reference

Error : UrlHelper.Link must not return null

I am creating REST Services. Here I want to create a Post service. Data is inserted into a database, but in response I got this error
UrlHelper.Link must not return null..
My Code
[HttpPost]
[Route("api/CourseRegistrations")]
[ResponseType(typeof(CourseRegistration))]
public IHttpActionResult PostCourseRegistration(CourseRegistration courseRegistration)
{
if (!ModelState.IsValid)
{
return BadRequest(ModelState);
}
db.CourseRegistrations.Add(courseRegistration);
db.SaveChanges();
return CreatedAtRoute("DefaultApi", new { id = courseRegistration.course_id }, courseRegistration);
}

I assumed you're using default setting inside WebApiConfig class in App_Start folder like this:
public static class WebApiConfig {
public static void Register(HttpConfiguration config) {
config.Routes.MapHttpRoute(
name: "DefaultApi",
routeTemplate: "api/{controller}/{id}",
defaults: new { id = RouteParameter.Optional }
);
}
}
Thus it is necessary to provide controller name parameter in CreatedAtRoute method, as in example below:
return CreatedAtRoute("DefaultApi", new { controller = "ApiControllerName", id = courseRegistration.course_id }, courseRegistration);
However, since RouteAttribute is present, it indicates that attribute routing is enabled, then you should provide route name for GET route with proper parameter name and then set POST route as shown in example below:
// GET method
[HttpGet]
[Route("api/CourseRegistrations/{id}", Name = "GetCourseRegistrationById")]
[ResponseType(typeof(CourseRegistration))]
public IHttpActionResult GetCourseRegistration(int id)
{
// do something
}
// POST method
[HttpPost]
[Route("api/CourseRegistrations")]
public IHttpActionResult PostCourseRegistration(CourseRegistration courseRegistration)
{
if (!ModelState.IsValid)
{
return BadRequest(ModelState);
}
db.CourseRegistrations.Add(courseRegistration);
db.SaveChanges();
// replace 'DefaultApi' with route name for redirect to GET method
return CreatedAtRoute("GetCourseRegistrationById", new { id = courseRegistration.course_id }, courseRegistration);
}
Note:
1) The parameter name contained inside CreatedAtRoute must match with target parameter name used in action method, otherwise the UrlHelper.Link() method will return null.
2) The route name in RouteAttribute should be different from action method name to avoid confusion.
Reference:
Attribute Routing in ASP.NET Web API 2: Route Names
Related issue:
Attribute Routing and CreatedAtRoute

Can I have multiple POST methods in WebAPI/MVC on same route? [duplicate]

I am starting to use MVC4 Web API project, I have controller with multiple HttpPost methods. The Controller looks like the following:
Controller
public class VTRoutingController : ApiController
{
[HttpPost]
public MyResult Route(MyRequestTemplate routingRequestTemplate)
{
return null;
}
[HttpPost]
public MyResult TSPRoute(MyRequestTemplate routingRequestTemplate)
{
return null;
}
}
Here MyRequestTemplate represents the template class responsible for handling the Json coming through the request.
Error:
When I make a request using Fiddler for http://localhost:52370/api/VTRouting/TSPRoute or http://localhost:52370/api/VTRouting/Route I get an error:
Multiple actions were found that match the request
If I remove one of the above method it works fine.
Global.asax
I have tried modifying the default routing table in global.asax, but I am still getting the error, I think I have problem in defining routes in global.asax. Here is what I am doing in global.asax.
public static void RegisterRoutes(RouteCollection routes)
{
routes.MapHttpRoute(
name: "MyTSPRoute",
routeTemplate: "api/VTRouting/TSPRoute",
defaults: new { }
);
routes.MapHttpRoute(
name: "MyRoute",
routeTemplate: "api/VTRouting/Route",
defaults: new { action="Route" }
);
}
I am making the request in Fiddler using POST, passing json in RequestBody for MyRequestTemplate.

You can have multiple actions in a single controller.
For that you have to do the following two things.
First decorate actions with ActionName attribute like
[ActionName("route")]
public class VTRoutingController : ApiController
{
[ActionName("route")]
public MyResult PostRoute(MyRequestTemplate routingRequestTemplate)
{
return null;
}
[ActionName("tspRoute")]
public MyResult PostTSPRoute(MyRequestTemplate routingRequestTemplate)
{
return null;
}
}
Second define the following routes in WebApiConfig file.
// Controller Only
// To handle routes like `/api/VTRouting`
config.Routes.MapHttpRoute(
name: "ControllerOnly",
routeTemplate: "api/{controller}"
);
// Controller with ID
// To handle routes like `/api/VTRouting/1`
config.Routes.MapHttpRoute(
name: "ControllerAndId",
routeTemplate: "api/{controller}/{id}",
defaults: null,
constraints: new { id = #"^\d+$" } // Only integers
);
// Controllers with Actions
// To handle routes like `/api/VTRouting/route`
config.Routes.MapHttpRoute(
name: "ControllerAndAction",
routeTemplate: "api/{controller}/{action}"
);

Another solution to your problem would be to use Route which lets you specify the route on the method by annotation:
[RoutePrefix("api/VTRouting")]
public class VTRoutingController : ApiController
{
[HttpPost]
[Route("Route")]
public MyResult Route(MyRequestTemplate routingRequestTemplate)
{
return null;
}
[HttpPost]
[Route("TSPRoute")]
public MyResult TSPRoute(MyRequestTemplate routingRequestTemplate)
{
return null;
}
}

use:
routes.MapHttpRoute(
name: "DefaultApi",
routeTemplate: "api/{controller}/{action}/{id}",
defaults: new { id = RouteParameter.Optional }
);
it's not a RESTful approach anymore, but you can now call your actions by name (rather than let the Web API automatically determine one for you based on the verb) like this:
[POST] /api/VTRouting/TSPRoute
[POST] /api/VTRouting/Route
Contrary to popular belief, there is nothing wrong with this approach, and it's not abusing Web API. You can still leverage on all the awesome features of Web API (delegating handlers, content negotiation, mediatypeformatters and so on) - you just ditch the RESTful approach.

A web api endpoint (controller) is a single resource that accepts get/post/put/delete verbs. It is not a normal MVC controller.
Necessarily, at /api/VTRouting there can only be one HttpPost method that accepts the parameters you are sending. The function name does not matter, as long as you are decorating with the [http] stuff. I've never tried, though.
Edit: This does not work. In resolving, it seems to go by the number of parameters, not trying to model-bind to the type.
You can overload the functions to accept different parameters. I am pretty sure you would be OK if you declared it the way you do, but used different (incompatible) parameters to the methods. If the params are the same, you are out of luck as model binding won't know which one you meant.
[HttpPost]
public MyResult Route(MyRequestTemplate routingRequestTemplate) {...}
[HttpPost]
public MyResult TSPRoute(MyOtherTemplate routingRequestTemplate) {...}
This part works
The default template they give when you create a new one makes this pretty explicit, and I would say you should stick with this convention:
public class ValuesController : ApiController
{
// GET is overloaded here. one method takes a param, the other not.
// GET api/values
public IEnumerable<string> Get() { .. return new string[] ... }
// GET api/values/5
public string Get(int id) { return "hi there"; }
// POST api/values (OVERLOADED)
public void Post(string value) { ... }
public void Post(string value, string anotherValue) { ... }
// PUT api/values/5
public void Put(int id, string value) {}
// DELETE api/values/5
public void Delete(int id) {}
}
If you want to make one class that does many things, for ajax use, there is no big reason to not use a standard controller/action pattern. The only real difference is your method signatures aren't as pretty, and you have to wrap things in Json( returnValue) before you return them.
Edit:
Overloading works just fine when using the standard template (edited to include) when using simple types. I've gone and tested the other way too, with 2 custom objects with different signatures. Never could get it to work.
Binding with complex objects doesn't look "deep", so thats a no-go
You could get around this by passing an extra param, on the query string
A better writeup than I can give on available options
This worked for me in this case, see where it gets you. Exception for testing only.
public class NerdyController : ApiController
{
public void Post(string type, Obj o) {
throw new Exception("Type=" + type + ", o.Name=" + o.Name );
}
}
public class Obj {
public string Name { get; set; }
public string Age { get; set; }
}
And called like this form the console:
$.post("/api/Nerdy?type=white", { 'Name':'Slim', 'Age':'21' } )

It is Possible to add Multiple Get and Post methods in the same Web API Controller. Here default Route is Causing the Issue. Web API checks for Matching Route from Top to Bottom and Hence Your Default Route Matches for all Requests. As per default route only one Get and Post Method is possible in one controller. Either place the following code on top or Comment Out/Delete Default Route
config.Routes.MapHttpRoute("API Default",
"api/{controller}/{action}/{id}",
new { id = RouteParameter.Optional });

When creating another Http Method add [HttpPost("Description")]
[HttpPost("Method1")]
public DataType Method1(MyRequestTemplate routingRequestTemplate)
{
return null;
}
[HttpPost("Method2")]
public DataType Method2(MyRequestTemplate routingRequestTemplate){}

Put Route Prefix [RoutePrefix("api/Profiles")] at the controller level and put a route at action method [Route("LikeProfile")]. Don't need to change anything in global.asax file
namespace KhandalVipra.Controllers
{
[RoutePrefix("api/Profiles")]
public class ProfilesController : ApiController
{
// POST: api/Profiles/LikeProfile
[Authorize]
[HttpPost]
[Route("LikeProfile")]
[ResponseType(typeof(List<Like>))]
public async Task<IHttpActionResult> LikeProfile()
{
}
}
}

You can use this approach :
public class VTRoutingController : ApiController
{
[HttpPost("Route")]
public MyResult Route(MyRequestTemplate routingRequestTemplate)
{
return null;
}
[HttpPost("TSPRoute")]
public MyResult TSPRoute(MyRequestTemplate routingRequestTemplate)
{
return null;
}
}

I think the question has already been answered. I was also looking for something a webApi controller that has same signatured mehtods but different names. I was trying to implement the Calculator as WebApi. Calculator has 4 methods with the same signature but different names.
public class CalculatorController : ApiController
{
[HttpGet]
[ActionName("Add")]
public string Add(int num1 = 1, int num2 = 1, int timeDelay = 1)
{
Thread.Sleep(1000 * timeDelay);
return string.Format("Add = {0}", num1 + num2);
}
[HttpGet]
[ActionName("Sub")]
public string Sub(int num1 = 1, int num2 = 1, int timeDelay = 1)
{
Thread.Sleep(1000 * timeDelay);
return string.Format("Subtract result = {0}", num1 - num2);
}
[HttpGet]
[ActionName("Mul")]
public string Mul(int num1 = 1, int num2 = 1, int timeDelay = 1)
{
Thread.Sleep(1000 * timeDelay);
return string.Format("Multiplication result = {0}", num1 * num2);
}
[HttpGet]
[ActionName("Div")]
public string Div(int num1 = 1, int num2 = 1, int timeDelay = 1)
{
Thread.Sleep(1000 * timeDelay);
return string.Format("Division result = {0}", num1 / num2);
}
}
and in the WebApiConfig file you already have
config.Routes.MapHttpRoute(
name: "DefaultApi",
routeTemplate: "api/{controller}/{action}/{id}",
defaults: new { id = RouteParameter.Optional });
Just set the authentication / authorisation on IIS and you are done!
Hope this helps!

Best and simplest explanation I have seen on this topic -
http://www.binaryintellect.net/articles/9db02aa1-c193-421e-94d0-926e440ed297.aspx
Edited -
I got it working with only Route, and did not need RoutePrefix.
For example, in the controller
[HttpPost]
[Route("[action]")]
public IActionResult PostCustomer
([FromBody]CustomerOrder obj)
{
}
and
[HttpPost]
[Route("[action]")]
public IActionResult PostCustomerAndOrder
([FromBody]CustomerOrder obj)
{
}
Then, the function name goes in jquery as either -
options.url = "/api/customer/PostCustomer";
or
options.url = "/api/customer/PostCustomerAndOrder";

I am using .Net6. please find the following code. I have achieve like the following.
using Microsoft.AspNetCore.Http;
using Microsoft.AspNetCore.Mvc;
namespace ProjectName.Controllers
{
[Route("[controller]")]
[ApiController]
public class WizardAPIController : ControllerBase
{
[HttpGet("Methord1")]
public async Task<IActionResult> Methord1()
{
return Ok("all good");
}
[HttpGet("Methord2")]
public async Task<IActionResult> Methord2()
{
return Ok("all good");
}
}
}

public class Journal : ApiController
{
public MyResult Get(journal id)
{
return null;
}
}
public class Journal : ApiController
{
public MyResult Get(journal id, publication id)
{
return null;
}
}
I am not sure whether overloading get/post method violates the concept of restfull api,but it workds. If anyone could've enlighten on this matter. What if I have a uri as
uri:/api/journal/journalid
uri:/api/journal/journalid/publicationid
so as you might seen my journal sort of aggregateroot, though i can define another controller for publication solely and pass id number of publication in my url however this gives much more sense. since my publication would not exist without journal itself.

Web API Routing Not Recognising Parameters

I have the following WebAPI controller:
namespace MyApp.WebApi.Controllers
{
[RoutePrefix("api/listing")]
public class ListingController : ApiController
{
[Route("{firstparam:int?}/{nextparam:int?}")]
public IEnumerable<ListItem> Get(int firstparam = 100, int nextparam = 12)
{
// firstparam is always 100, and nextparam is always 12
However, I've tried specifying the URL:
http://localhost:56004/#/listing?firstparam=2
If I specify the URL like this:
http://localhost:56004/#/listing/2
Then it breaks the routing.
Clearly I'm missing something regarding routing; please could someone point me in the right direction?

You are using multiple optional parameter which don't work well for routeTemplates. Normally the last parameter tends to be the optional parameter.
Documentation: Attribute Routing in ASP.NET Web API 2: Optional URI Parameters and Default Values
FIrst make sure the attribute routing is enabled
public static class WebApiConfig
{
public static void Register(HttpConfiguration config)
{
// Attribute routing.
config.MapHttpAttributeRoutes();
// Convention-based routing.
config.Routes.MapHttpRoute(
name: "DefaultApi",
routeTemplate: "api/{controller}/{id}",
defaults: new { id = RouteParameter.Optional }
);
}
}
To get what you are after
[RoutePrefix("api/listing")]
public class ListingController : ApiController {
//GET api/listing
//GET api/listing?firstparam=x
//GET api/listing?nextparam=y
//GET api/listing?firstparam=x&nextparam=y
[HttpGet]
[Route("")]
public IEnumerable<ListItem> Get(int firstparam = 100, int nextparam = 12) { ... }
}
The problem with having multiple inline parameters that are optional is that the router wont know which to use which is why they tend to be at the end of the url.
However to get them inline like how you mentioned in your example you are going to need multiple routes.
[RoutePrefix("api/listing")]
public class ListingController : ApiController {
//GET api/listing
[HttpGet]
[Route("")]
public IEnumerable<ListItem> Get() { return Get(100, 12); }
//GET api/listing/2
//GET api/listing/2/5
[HttpGet]
[Route("{firstparam:int}/{nextparam:int?}")]
public IEnumerable<ListItem> Get(int firstparam, int nextparam = 12) { ... }
}

You could try using [FromUri] attribute within the params of the Get() method to extract any query params being passed into the "/listing" uri along with a class that consists of int properties firstparam and secondparam.
namespace MyApp.WebApi.Controllers
{
[RoutePrefix("api/listing")]
public class ListingController : ApiController
{
[Route("")]
[HttpGet]
public IEnumerable<ListItem> Get([FromUri] ClassRepresentingParams params)
{
Hopefully that helps.

Web api route wint action require names for multiple get method

I have an asp.net mvc controller named product.
public class ProductController : ApiController
{
[HttpGet]
public IHttpActionResult Get()
{
return Ok("product");
}
}
And my route is like this.
config.Routes.MapHttpRoute("DefaultRoute",
"api/{controller}/{id}",
new { id = RouteParameter.Optional });
I can access the product Get method like this url: localhost:2541/api/product
And I need some estra get methots.
public class ProductController : ApiController
{
[HttpGet]
public IHttpActionResult Get()
{
return Ok("product");
}
[HttpGet]
public IHttpActionResult Hello()
{
return Ok("Hello from product");
}
}
And I set new route.
config.Routes.MapHttpRoute("ActionsRoute",
"api/{controller}/{action}/{id}",
new { id = RouteParameter.Optional });
But I can not access to localhost:2541/api/product
Error:
Multiple actions were found that match the request: Get

That is because by including {action} route parameter it is now required to include the name of the action in the request other wise it will not know which action to select. like
localhost:2541/api/product/Get
If the root is still desired then include default when mapping route.
config.Routes.MapHttpRoute("ActionsRoute",
"api/{controller}/{action}/{id}",
new { action = "Get", id = RouteParameter.Optional });
With that done, the calls below will map as followed
GET localhost:2541/api/product --> ProductController.Get
GET localhost:2541/api/product/Get --> ProductController.Get
GET localhost:2541/api/product/Hello --> ProductController.Hello

Custom method names in ASP.NET Web API

I'm converting from the WCF Web API to the new ASP.NET MVC 4 Web API. I have a UsersController, and I want to have a method named Authenticate. I see examples of how to do GetAll, GetOne, Post, and Delete, however what if I want to add extra methods into these services? For instance, my UsersService should have a method called Authenticate where they pass in a username and password, however it doesn't work.
public class UsersController : BaseApiController
{
public string GetAll()
{
return "getall!";
}
public string Get(int id)
{
return "get 1! " + id;
}
public User GetAuthenticate(string userName, string password, string applicationName)
{
LogWriter.Write(String.Format("Received authenticate request for username {0} and password {1} and application {2}",
userName, password, applicationName));
//check if valid leapfrog login.
var decodedUsername = userName.Replace("%40", "#");
var encodedPassword = password.Length > 0 ? Utility.HashString(password) : String.Empty;
var leapFrogUsers = LeapFrogUserData.FindAll(decodedUsername, encodedPassword);
if (leapFrogUsers.Count > 0)
{
return new User
{
Id = (uint)leapFrogUsers[0].Id,
Guid = leapFrogUsers[0].Guid
};
}
else
throw new HttpResponseException("Invalid login credentials");
}
}
I can browse to myapi/api/users/ and it will call GetAll and I can browse to myapi/api/users/1 and it will call Get, however if I call myapi/api/users/authenticate?username={0}&password={1} then it will call Get (NOT Authenticate) and error:
The parameters dictionary contains a null entry for parameter 'id' of non-nullable type 'System.Int32' for method 'System.String Get(Int32)' in 'Navtrak.Services.WCF.NavtrakAPI.Controllers.UsersController'. An optional parameter must be a reference type, a nullable type, or be declared as an optional parameter.
How can I call custom method names such as Authenticate?

By default the route configuration follows RESTFul conventions meaning that it will accept only the Get, Post, Put and Delete action names (look at the route in global.asax => by default it doesn't allow you to specify any action name => it uses the HTTP verb to dispatch). So when you send a GET request to /api/users/authenticate you are basically calling the Get(int id) action and passing id=authenticate which obviously crashes because your Get action expects an integer.
If you want to have different action names than the standard ones you could modify your route definition in global.asax:
Routes.MapHttpRoute(
name: "DefaultApi",
routeTemplate: "api/{controller}/{action}/{id}",
defaults: new { action = "get", id = RouteParameter.Optional }
);
Now you can navigate to /api/users/getauthenticate to authenticate the user.

This is the best method I have come up with so far to incorporate extra GET methods while supporting the normal REST methods as well. Add the following routes to your WebApiConfig:
routes.MapHttpRoute("DefaultApiWithId", "Api/{controller}/{id}", new { id = RouteParameter.Optional }, new { id = #"\d+" });
routes.MapHttpRoute("DefaultApiWithAction", "Api/{controller}/{action}");
routes.MapHttpRoute("DefaultApiGet", "Api/{controller}", new { action = "Get" }, new { httpMethod = new HttpMethodConstraint(HttpMethod.Get) });
routes.MapHttpRoute("DefaultApiPost", "Api/{controller}", new {action = "Post"}, new {httpMethod = new HttpMethodConstraint(HttpMethod.Post)});
I verified this solution with the test class below. I was able to successfully hit each method in my controller below:
public class TestController : ApiController
{
public string Get()
{
return string.Empty;
}
public string Get(int id)
{
return string.Empty;
}
public string GetAll()
{
return string.Empty;
}
public void Post([FromBody]string value)
{
}
public void Put(int id, [FromBody]string value)
{
}
public void Delete(int id)
{
}
}
I verified that it supports the following requests:
GET /Test
GET /Test/1
GET /Test/GetAll
POST /Test
PUT /Test/1
DELETE /Test/1
Note That if your extra GET actions do not begin with 'Get' you may want to add an HttpGet attribute to the method.

I am days into the MVC4 world.
For what its worth, I have a SitesAPIController, and I needed a custom method, that could be called like:
http://localhost:9000/api/SitesAPI/Disposition/0
With different values for the last parameter to get record with different dispositions.
What Finally worked for me was:
The method in the SitesAPIController:
// GET api/SitesAPI/Disposition/1
[ActionName("Disposition")]
[HttpGet]
public Site Disposition(int disposition)
{
Site site = db.Sites.Where(s => s.Disposition == disposition).First();
return site;
}
And this in the WebApiConfig.cs
// this was already there
config.Routes.MapHttpRoute(
name: "DefaultApi",
routeTemplate: "api/{controller}/{id}",
defaults: new { id = RouteParameter.Optional }
);
// this i added
config.Routes.MapHttpRoute(
name: "Action",
routeTemplate: "api/{controller}/{action}/{disposition}"
);
For as long as I was naming the {disposition} as {id} i was encountering:
{
"Message": "No HTTP resource was found that matches the request URI 'http://localhost:9000/api/SitesAPI/Disposition/0'.",
"MessageDetail": "No action was found on the controller 'SitesAPI' that matches the request."
}
When I renamed it to {disposition} it started working. So apparently the parameter name is matched with the value in the placeholder.
Feel free to edit this answer to make it more accurate/explanatory.

Web Api by default expects URL in the form of api/{controller}/{id}, to override this default routing. you can set routing with any of below two ways.
First option:
Add below route registration in WebApiConfig.cs
config.Routes.MapHttpRoute(
name: "CustomApi",
routeTemplate: "api/{controller}/{action}/{id}",
defaults: new { id = RouteParameter.Optional }
);
Decorate your action method with HttpGet and parameters as below
[HttpGet]
public HttpResponseMessage ReadMyData(string param1,
string param2, string param3)
{
// your code here
}
for calling above method url will be like below
http://localhost:[yourport]/api/MyData/ReadMyData?param1=value1&param2=value2&param3=value3
Second option
Add route prefix to Controller class and Decorate your action method with HttpGet as below.
In this case no need change any WebApiConfig.cs. It can have default routing.
[RoutePrefix("api/{controller}/{action}")]
public class MyDataController : ApiController
{
[HttpGet]
public HttpResponseMessage ReadMyData(string param1,
string param2, string param3)
{
// your code here
}
}
for calling above method url will be like below
http://localhost:[yourport]/api/MyData/ReadMyData?param1=value1&param2=value2&param3=value3

In case you're using ASP.NET 5 with ASP.NET MVC 6, most of these answers simply won't work because you'll normally let MVC create the appropriate route collection for you (using the default RESTful conventions), meaning that you won't find any Routes.MapRoute() call to edit at will.
The ConfigureServices() method invoked by the Startup.cs file will register MVC with the Dependency Injection framework built into ASP.NET 5: that way, when you call ApplicationBuilder.UseMvc() later in that class, the MVC framework will automatically add these default routes to your app. We can take a look of what happens behind the hood by looking at the UseMvc() method implementation within the framework source code:
public static IApplicationBuilder UseMvc(
[NotNull] this IApplicationBuilder app,
[NotNull] Action<IRouteBuilder> configureRoutes)
{
// Verify if AddMvc was done before calling UseMvc
// We use the MvcMarkerService to make sure if all the services were added.
MvcServicesHelper.ThrowIfMvcNotRegistered(app.ApplicationServices);
var routes = new RouteBuilder
{
DefaultHandler = new MvcRouteHandler(),
ServiceProvider = app.ApplicationServices
};
configureRoutes(routes);
// Adding the attribute route comes after running the user-code because
// we want to respect any changes to the DefaultHandler.
routes.Routes.Insert(0, AttributeRouting.CreateAttributeMegaRoute(
routes.DefaultHandler,
app.ApplicationServices));
return app.UseRouter(routes.Build());
}
The good thing about this is that the framework now handles all the hard work, iterating through all the Controller's Actions and setting up their default routes, thus saving you some redundant work.
The bad thing is, there's little or no documentation about how you could add your own routes. Luckily enough, you can easily do that by using either a Convention-Based and/or an Attribute-Based approach (aka Attribute Routing).
Convention-Based
In your Startup.cs class, replace this:
app.UseMvc();
with this:
app.UseMvc(routes =>
{
// Route Sample A
routes.MapRoute(
name: "RouteSampleA",
template: "MyOwnGet",
defaults: new { controller = "Items", action = "Get" }
);
// Route Sample B
routes.MapRoute(
name: "RouteSampleB",
template: "MyOwnPost",
defaults: new { controller = "Items", action = "Post" }
);
});
Attribute-Based
A great thing about MVC6 is that you can also define routes on a per-controller basis by decorating either the Controller class and/or the Action methods with the appropriate RouteAttribute and/or HttpGet / HttpPost template parameters, such as the following:
using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using Microsoft.AspNet.Mvc;
namespace MyNamespace.Controllers
{
[Route("api/[controller]")]
public class ItemsController : Controller
{
// GET: api/items
[HttpGet()]
public IEnumerable<string> Get()
{
return GetLatestItems();
}
// GET: api/items/5
[HttpGet("{num}")]
public IEnumerable<string> Get(int num)
{
return GetLatestItems(5);
}
// GET: api/items/GetLatestItems
[HttpGet("GetLatestItems")]
public IEnumerable<string> GetLatestItems()
{
return GetLatestItems(5);
}
// GET api/items/GetLatestItems/5
[HttpGet("GetLatestItems/{num}")]
public IEnumerable<string> GetLatestItems(int num)
{
return new string[] { "test", "test2" };
}
// POST: /api/items/PostSomething
[HttpPost("PostSomething")]
public IActionResult Post([FromBody]string someData)
{
return Content("OK, got it!");
}
}
}
This controller will handle the following requests:
[GET] api/items
[GET] api/items/5
[GET] api/items/GetLatestItems
[GET] api/items/GetLatestItems/5
[POST] api/items/PostSomething
Also notice that if you use the two approaches togheter, Attribute-based routes (when defined) would override Convention-based ones, and both of them would override the default routes defined by UseMvc().
For more info, you can also read the following post on my blog.

See this article for a longer discussion of named actions. It also shows that you can use the [HttpGet] attribute instead of prefixing the action name with "get".
http://www.asp.net/web-api/overview/web-api-routing-and-actions/routing-in-aspnet-web-api

Web APi 2 and later versions support a new type of routing, called attribute routing. As the name implies, attribute routing uses attributes to define routes. Attribute routing gives you more control over the URIs in your web API. For example, you can easily create URIs that describe hierarchies of resources.
For example:
[Route("customers/{customerId}/orders")]
public IEnumerable<Order> GetOrdersByCustomer(int customerId) { ... }
Will perfect and you don't need any extra code for example in WebApiConfig.cs.
Just you have to be sure web api routing is enabled or not in WebApiConfig.cs , if not you can activate like below:
// Web API routes
config.MapHttpAttributeRoutes();
You don't have to do something more or change something in WebApiConfig.cs. For more details you can have a look this article.

Just modify your WebAPIConfig.cs as bellow
Routes.MapHttpRoute(
name: "DefaultApi",
routeTemplate: "api/{controller}/{action}/{id}",
defaults: new { action = "get", id = RouteParameter.Optional });
Then implement your API as bellow
// GET: api/Controller_Name/Show/1
[ActionName("Show")]
[HttpGet]
public EventPlanner Id(int id){}