I have my API for a small part of my application split over two controllers, because of (external) requirements on the casing of JSON data in the API (some requests should use camelCasing, while others should use PascalCasing).
Now, I have a url that I want to map with PascalCasing for GET, but camelCasing for PUT, so I tried the following:
[PascalCasing] // custom attribute, part of our code
// We configure all controllers that *don't* have this to use
// camelCasing
public class PascalCasedController : ApiController
{
[HttpGet]
[Route("url/to/my/resource/{id}")]
public IHttpActionResult(int id)
{
return Ok(GetResource(id));
}
}
public class CamelCasedController : ApiController
{
[HttpPut]
[Route("url/to/my/resource/{id}")]
public IHttpActionResult(int id, Resource resource)
{
SaveResource(id, resource);
return Ok();
}
}
The GET request works as expected, but if I try to PUT something there with Fiddler, I get the following error message:
Multiple controller types were found that match the URL. This can happen if attribute routes on multiple controllers match the requested URL.
The request has found the following matching controller types:
MyProject.PascalCaseController
MyProject.CamelCaseController
I realize this is probably because WebAPI maps routes to controllers first and actions next, but if HTTP methods are considered, there really isn't any ambiguity here. Is there any way that I can tell WebAPI how to do this, without having to have the methods in the same controller?
#Tomas - There's an interface "System.Web.Http.Dispatcher.IHttpControllerSelector" exposed in System.Web.Http assembly. You can use that interface and create your own HttpControllerSelector. You can then replace the DefaultControllerSelector with your custom controller selector in the HttpConfiguration during AreaRegistration.
httpConfig.Services.Replace(typeof(IHttpControllerSelector), new CustomControllerSelector(services.GetHttpControllerSelector()));
In this custom controller selector you can write your own implementation of SelectController() method of IHttpControllerSelector in which you can call GetControllerMapping() method of IHttpControllerSelector. This will give you the list of all the controllers registered. For every controller you can check for the DeclaredMethods and check for the CustomAttributes for each of the DeclaredMethods. In your case it will be either HttpGetAttribute or HttpPutAttribute.
Check the Method type of the incoming HttpRequestMessage (GET/PUT) and compare it against the value of the CustomAttributes. If you find a match of the combination of incoming request URL and the the respective Http Verb then you take that HttpControllerDiscriptor and return it from the SelectController() method..
This will allow you to have same URL with different methods in two different controllers.
Related
**web-api**
As u can see I have to develop different api . For this I have created a MasterController. But I am getting an problem. I am using Postman for testing and I am getting the following problem. Please help me to resolve this issue. I am getting multiple match points. Please help me resolve the issue.
Microsoft.AspNetCore.Routing.Matching.AmbiguousMatchException: The request matched multiple endpoints.
using Microsoft.AspNetCore.Mvc;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using VENUS.HRMS.API.Filters;
using VENUS.HRMS.DATA.Data;
using VENUS.HRMS.DATA.Models;
namespace VENUS.HRMS.API.Controllers
{
[ApiController]
[Route("[controller]")]
public class MasterController : Controller
{
public IActionResult Index()
{
return View();
}
[HttpGet]
[AuthorizationFilter]
public IEnumerable<TblMstEmpRole> Get()
{
var emprole = new EmpRoleData().GetMstEmpRole();
return emprole;
}
[HttpGet]
[AuthorizationFilter]
public IEnumerable<TblMstState> GetState()
{
var state = new StateData().GetMstState();
return state;
}
[HttpGet]
[AuthorizationFilter]
public IEnumerable<TblMstCity> GetCity()
{
var city = new CityData().GetMstCity();
return city;
}
}
}
The issue is exactly what error says: The request matched multiple endpoints
Remember when calling an API, the function name does not matter. The function name is only for "Internal" use within your C# applicaiton. The name of the API endpoint correlates to it's route. This route is set with either the [Route()] attribute or within the [HttpGet()] attribute.
For example you have 3 functions:
[HttpGet]
public IEnumerable<TblMstEmpRole> Get()
[HttpGet]
public IEnumerable<TblMstState> GetState()
[HttpGet]
public IEnumerable<TblMstCity> GetCity()
The full route for these three functions respectively are:
Get --> /Master/
Get --> /Master/
Get --> /Master/
Yes all thee are the same. And that is the exact issue you are having. To fix this change the Route for your endpoints like this:
[HttpGet]
public IEnumerable<TblMstEmpRole> Get()
[HttpGet("State")]
public IEnumerable<TblMstState> GetState()
[HttpGet("City")]
public IEnumerable<TblMstCity> GetCity()
Now the routes will look like this:
Get --> /Master/
Get --> /Master/State
Get --> /Master/City
The rule is:
You can only have one route name per Http operation.
Different HTTP Methods
[HttpGet] is one of the attributes which has a GET method, however, there are many other methods such as POST, HEAD, PUT, OPTIONS, DELETE, CONNECT, TRACE and PATCH.
To utilize them through an API endpoint all you need to do is add it to the function. All the attributes have the [Http***] format. Example Post and Put will be:
[HttpPost]
[HttoPut]
And has mentioned a little above, you can only have one Route for each method. See examples below:
// PATH: GET --> /Master/
[HttpGet]
public IEnumerable<TblMstEmpRole> GETGet()
// PATH: POST --> /Master/
[HttpPost]
public IEnumerable<TblMstEmpRole> POSTGet()
The above example is VALID. Even though we have two functions with the same route, they do have different Http Methods and as such are uniquely identifiable.
Why Different Methods
Each method has it's own quirks and uses. Depending on the method, some things are allowed and some are not. When a client makes a query to a server and sends something, that is called a Http Request. The method for either getting or setting it is the Http Method, example GET, POST, PUT...
A Http Request has the following structure:
Headers
Parameters
Body
Footer
If we were to use the GET method, then you are telling the endpoint that it should ignore the Body of the request.
If we were to use the HEAD method then we are telling the endpoint that we are only interested in the Headers section of the request.
Now to figure out which to use and when can be tricky, but as a basic rule of thumb you can use this:
GET - You are only fetching data and not sending anything in the body
POST - When you are creating something in the database or sending data in the body
PUT - Similar to Post, but only when you are updating something
DELETE - When you are removing something.
These are the basic 4 any beginner to intermediate should be aware of. For more information on what method to use see: https://www.w3schools.com/tags/ref_httpmethods.asp
My issue is similar to Web Api Routing : Multiple controller types were found that match the URL but I want to keep them in separate controllers.
From the comments, 2 preexisting answers are good workarounds but do not solve the actual issue I'm trying to resolve.
The URLs I'm making up are similar to nested directories in a file system OR are very similar to Firebase URLs.
/BiggestSet/{BiggestSetCode}/Subset1/{Subset1Code}/SubsetOfSubset1/{SubsetOfSubset1}
... etc all the way down to where ever the tree stops. Think of it as a tree of data.
/Collection/{Instance}/Collection/{Instance}
The issue I have is that at the /Collection level I want to also provide specific collection level operations. Like Add and search and other collection specific Operations Collection/ProccessData
Collection Controller:
/Collection/Add
/Collection/ProcessDataOnTheColleciton
Instance Controller:
/Collection/{InstanceCode}
/Collection/{InstanceCode}/ProcessOnTheInstance
The problem I'm having is the Collection/ProcessData clashes with the instance Collection/{InstanceCode}
NOTE: 1 is an parameter and the other is a constant.
If you setup the controllers so that collection and Instance are in the same controller. the /{InstanceCode} doesn't clash with the /ProcessData
BUT
If you setup so the controllers are split into logical functions WebAPI gives the error Multiple controller types were found that match the URL.
Does anyone know how to modify attribute routing to somehow behave as if they are in the same controller OR to prioritize the constant over the parameter across controllers?
To keep two separate controllers and still have such routes you can use regular expression route constraints. This way you can specify for the instanceCode you accept everything except the actions from the other controller.
Here is a sample of how to configure routes like that:
public class CollectionController : ApiController
{
[HttpGet]
[Route("Collection/Add")]
public string Add()
{
return $"CollectionController = Collection/Add";
}
[HttpGet]
[Route("Collection/Process")]
public string Process()
{
return $"CollectionController = Collection/Process";
}
}
public class InstanceController : ApiController
{
[HttpGet]
[Route("Collection/{instanceCode:regex(^(?!Add$|Process$).*)}")]
public string Get(string instanceCode)
{
return $"InstanceController = Collection/{instanceCode}";
}
[HttpGet]
[Route("Collection/{instanceCode:regex(^(?!Add$|Process$).*)}/Process")]
public string Process(string instanceCode)
{
return $"InstanceController = Collection/{instanceCode}/Process";
}
}
Here is also a link to the post that explains the regular expression used in the sample.
An even better option would be if you have a specific format for the instanceCode and set the regular expression to accept only this specific format. Then you would not need to modify the regular expression for every new action added. I include also a link to the documentation for all available Route constraints. There you can see all the available options. For example if your instance code is a number you don't even need a regular expression you can just restrict with the int constraint like this [Route("Collection/{instanceCode:int}")].
I have two controllers, ItemsController and SingleItemController which both inherit from ApiController. Both have RoutePrefix items/inventory defined on the controllers, like so:
[RoutePrefix("items/inventory")]
I'm using AttributeRouting in Web API 2.2.
In SingleItemController I have the following route:
[Route("{itemReference}")]
[HttpGet]
public ItemDTO GetItem(string itemReference)
In ItemsController I have the following route:
[Route("all")]
[HttpGet]
public List<ItemDTO> GetAllItems(DateTime dateFrom, DateTime dateTo)
When I try to hit the /items/inventory/all?dateFrom=2015-09-06&dateTo=2015-09-12 route, I get the following error:
Multiple controller types were found that match the URL. This can
happen if attribute routes on multiple controllers match the requested
URL. The request has found the following matching controller types:
ItemAPI.Controllers.ItemsController
ItemAPI.Controllers.SingleItemController
So {itemReference} route is conflicting with all route. Why is this? I would think that it reserves first all route and then allows an optional string route.
This is because it can't decide whether "all" is an item reference.
I had a similar issue recently where I had a controller with an "admin" route prefix.
To get round the issue I put a constraint on the parameter to ignore the word "admin".
So in your case you could do the following to ignore the word "all":
[Route("{itemReference:regex(^(?!all))})]
I have a standard CI web app, but I've decided to get the chaotic javascript in order using backbone. I had a whole pile of serialized forms/jQuery AJAX requests to various controller methods: authenticate, change_password, register_member, request_new_password, etc.., and don't quite understand how REST works instead. I'm using Phil Sturgeon's REST library for CI https://github.com/philsturgeon/codeigniter-restserver
Should every backbone model have a different api url? And what am I supposed to actually call the controller methods?
<?php
require(APPPATH.'/libraries/REST_Controller.php');
class RestApi extends REST_Controller
{
function get()
{
But it just 404s.
I just don't get how to replace the routing to fifty of my old methods based on a handful of HTTP methods. Does the name of the backbone model need to match something on the server side?
You have to name your functions index_HTTPMETHOD. In your example it would be:
class RestApi extends REST_Controller {
// this will handle GET http://.../RestApi
function index_get() {
}
// additionally this will handle POST http://.../RestApi
function index_post() {
}
// and so forth
// if you want to POST to http://.../RestApi/somefunc
function somefunc_post() {
}
}
the url-attribute of the model should match the server-side 'url' which returns the JSON that will make up the model's attributes. Backbone.js has default functionality to this, which is to match the model's collection url with it's id attribute. The collection url requirement can be foregone by overriding the urlRoot -function, in order to operate model's outside of collections.
If you want to be independent of the id -attribute as well, you sould override the url -attribute/function to provide your own url that matches to the model on the server, like this:
url: 'path/to/my/model'
or
url: function() { // Define the url as a function of some model properties
var path = this.model_root + '/' + 'some_other_url_fragment/' + this.chosen_model_identifier;
return path;
}
I'm creating a CMS using ASP.NET MVC, and by design, I've decided that each plugin (add-on) should have a key in the incoming HTTP request. Thus, I have this general route in my host application:
{pluginKey}/{controller}/{action}/{id}
I've created a custom controller factory which implements IControllerFactory and of course, it has a method to create controllers base on the ReqeustContext and controller name. However, I want to create an artificial HttpContext (alongside all other relevant objects like HttpRequest, RequestContext, RouteData, etc.) so that controllers of plugins won't misinterpret these URL segments wrongly. In other words, I want to cut the first part of the incoming URL, and make plugins think that they're processing this URL:
{controller}/{action}/{id}
How can I achieve this?
While you could create a new implementation of all the context classes, it seems like a bit of overkill. Why not use a derived Route Handler that applies the filtering functionality before returning the HttpHandler? Here's an example:
// To avoid conflicts with similarly named controllers, I find it to be good practice
// to create a route constraint with the set of all plugin names. If you don't have
// this function already, you should be able to access it with reflection (one time
// per app lifecycle) or you hard-code them. The point is to have a regex which ensures
// only valid plugins will get selected
string[] pluginNames = GetPluginNames();
string pluginNameRegex = string.Join("|",pluginNames);
Route pluginRoute = new Route (
url: "{pluginKey}/{controller}/{action}/{id}",
defaults: null,
constraints: new RouteValueDictionary(new { pluginKey = pluginNameRegex }),
routeHandler: new PluginRouteHandler()
});
// The custom route handler can modify your route data after receiving the RequestContext
// and then send it to the appropriate location. Here's an example (markdown code/untested)
// Note: You don't have to inherit from MvcRouteHandler (you could just implement IRouteHandler
// but I'm assuming you want Mvc functionality as the fallback)
public class PluginRouteHandler : MvcRouteHandler
{
public PluginRouteHandler(IControllerFactory controllerFactory)
: base(controllerFactory)
{}
protected override IHttpHandler GetHttpHandler(RequestContext requestContext){
if(ValidatePluginRoute(requestContext))
{
// we are going to remove the pluginKey from the RequestContext, It's probably wise
// to go ahead and add it to HttpContext.Items, in case you need the data later
requestContext.HttpContext.Items["pluginKey"] = requestContext.RouteData.Values["pluginKey"];
// now let's get ride of it, so your controller factory will process the
// requestContext as you have described.
requestContext.Values.Remove("pluginKey");
// the route will now be interpreted as described so let the flow go to the MvcRouteHandler's method
}
return base.GetHttpHandler(requestContext);
}
static bool ValidatePluginRoute(RequestContext requestContext){
return requestContext.RouteData.ContainsKey("pluginKey");
}
}