How can I resolve the error I am getting in web api? - asp.net-web-api

Question

**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;
}
}
}

Answer 1

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