Attribute Based Routing/Versioning in ASP.Net WEB API 2.0

Question

I'm trying to use versioning in Asp.Net Web API. Following is the structure of the project.

To support versioning I've added Microsoft.AspNet.WebApi.Versioning NuGet package. Following is the code snippet of WebApiConfig:

    public static void Register(HttpConfiguration config)
    {
        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 }
        );
    }

And below is the code from controller:

[ApiVersion("1.0")]
[RoutePrefix("api/v{version:apiVersion}/employeemanagement")]
public class EmployeeManagementController : ApiController
{
    [Route("GetTest")]
    [HttpGet]
    public string GetTest()
    {
        return "Hello World";
    }

    [Route("GetTest2")]
    [HttpGet]
    public string GetTest2()
    {
        return "Another Hello World";
    }

    [Route("saveemployeedata")]
    [HttpPost]
    public async Task<GenericResponse<int>> SaveEmployeeData(EmployeeData employeeData, ApiVersion apiVersion)
    {
        //code goes here
    }

    [Route("updateemployeedata")]
    [HttpPost]
    public async Task<GenericResponse<int>> UpdateEmployeeData([FromBody]int id, ApiVersion apiVersion)
    {
        //code goes here            
    }
}

If I use [FromBody] in UpdateEmployeeData, it gives following error:

{
"Message": "The request is invalid.",
"MessageDetail": "The parameters dictionary contains a null entry for parameter 'id' of non-nullable type 'System.Int32' for method 'System.Threading.Tasks.Task`1[AlphaTest.API.Models.ResponseModels.GenericResponse`1[System.Int32]] UpdateEmployeeData(Int32, Microsoft.Web.Http.ApiVersion)' in 'AlphaTest.API.Controllers.V1.EmployeeManagementController'. An optional parameter must be a reference type, a nullable type, or be declared as an optional parameter."
}

Following is the URL & data, I'm passing to generate above error: http://localhost:53963/api/v1.0/EmployeeManagement/updateemployeedata

If I remove[FromBody] it gives me 404 Not found error.

Please help me understand what I'm doing wrong here, which is causing above mentioned error.

Mohammed Sajid · Accepted Answer · 2020-06-13 23:33:40Z

1

You could use object that contains property called Id as parameter of the action UpdateEmployeeData not directly the int Id, like :

public class Request
{
    public int Id { get; set; }
}

The action will be :

[Route("updateemployeedata")]
[HttpPost]
public async Task<GenericResponse<int>> UpdateEmployeeData([FromBody]Request request, ApiVersion apiVersion)
{
    //code goes here            
}

I hope you find this helpful.

edited Jun 13, 2020 at 23:33

answered Jun 13, 2020 at 23:28

Mohammed Sajid

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3 Comments

Vivek Sharma Over a year ago

Yes. You're right. we can achieve desired result the way you mentioned. But what is wrong with the approach I'm following.

Gusman Over a year ago

@VivekSharma The problem in your code is that you are sending a object with a property called id, not an integer. look how it's enclosed in brackets and the value is set to a property. An integer would be directly the value on the body, nothing else, try to serialize in JSON an integer, the result you will get will be the number in plain text.

Mohammed Sajid Over a year ago

@VivekSharma you can use app.quicktype.io/?l=csharp to generate c# code from Json, that will help you if you have a complex json.

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