MVC和Web Api：请求的资源不支持http方法“ POST”

Question

So I've looked at all the questions relating to this problem and tried all the suggestions to no avail. I have a solution in Visual Studio 2019 which consists of multiple MVC projects. I want to add a Web Service which I have duly done. All good so far. So I have a call being made to this Web Service using ajax, thus:

            var apiLocation = getHostname(window.location.href, 0) + "/OLBWebService/api/";
            var obj = { "id": $('#salonDDL').val() };

            // populate the services drop down list based on the salon ID
            $.ajax({
                type: "POST",
                headers: {
                            'Content-Type': 'application/json', /*or whatever type is relevant */
                            'Accept': 'application/json' /* ditto */
                        },
                datatype: "json",  
                url: apiLocation + "Service/GetServicesForSalon",
                data: JSON.stringify(obj),  
                success: function (response) {
                    if (response.length > 0) {
                        $('#serviceDDL').empty();
                        var options = '';
                        options += "<option value='0' selected>Please select a service</option>";
                        for (var i = 0; i < response.length; i++) {
                            options += '<option value="' + response[i].Id + '">' + response[i].Name + '</option>';
                        }
                        $('#serviceDDL').append(options);
                    }
                },
                fail: function (error) {
                    alert(error.StatusText);
                }
            });

I currently have my routing in WebApiConfig.cs thus:

            config.MapHttpAttributeRoutes();

            config.Routes.MapHttpRoute(
                name: "DefaultApi",
                routeTemplate: "api/{controller}/{action}/{id}",
                defaults: new { id = RouteParameter.Optional }
            );

I set up a controller with methods thus: (the HttpPost is defined as being from the System.Web.Http namespace)

        [HttpPost]
        public IHttpActionResult GetServicesForSalon([FromBody]DefaultParams passedParams)
        {
            List<Service> service = new List<Service>();
            service = _ServiceService.GetServicesBySalonID(passedParams.id);

            try
            {
                return Json(service.Select(s => new { Id = s.ID, Name = s.Description }).OrderBy(s => s.Name));
            }
            catch (Exception ex)
            {
                _loggingService.LogError(ex, "Error in GetServicesForSalon with id of:" + passedParams.id.ToString());
                return null;
            }
        }

The DefaultParams being passed in are defined thus:

    public class DefaultParams
    {
        public int id { get; set; }
    }

When I run it, either in debug mode via Visual Studio 2019 or using Fiddler, I get the message "The requested resource does not support http method 'POST'".

The strange thing is I have an ajax call prior to this one which works. (the syntax is the original one I always use and I have tried this syntax in the problem call)

            $.ajax({  
                type: "POST",  
                url: apiLocation + "Salon/GetSalonsByOrg",  
                data: JSON.stringify(obj),  
                contentType: "application/json",  
                datatype: "json",  
                success: function (response) {
                    if (response.length > 0) {
                        $('#salonDDL').empty();
                        var options = '';
                        options += "<option value='0' selected>Please select a salon</option>";
                        for (var i = 0; i < response.length; i++) {
                            options += '<option value="' + response[i].Id +'">' + response[i].Name + '</option>';
                        }

                        $('#salonDDL').append(options);
                    } 
                },
                fail: function (error) {
                    alert(error.StatusText);
                }
            });

The controller is a different one and the method is defined thus: (the HttpPost is defined as being from the System.Web.Http namespace)

        [HttpPost]
        public IHttpActionResult GetSalonsByOrg([FromBody]GetSalonsByOrgParams passedParams)
        {
            List<Salon> salons = new List<Salon>();
            salons = _SalonService.GetSalonsByOrg(passedParams.id);

            try
            {
                if (passedParams.filter != null)
                {
                    return Json(salons.AsEnumerable().Where(s => s.City.ToLower().Contains(passedParams.filter.ToLower())).Select(s => new { Id = s.ID, Name = s.Name }).OrderBy(s => s.Name).ToList());
                }
                else
                {
                    return Json(salons.Select(s => new { Id = s.ID, Name = s.Name }).OrderBy(s => s.Name));
                }
            }
            catch (Exception ex)
            {
                _loggingService.LogError(ex, "Error in GetSalonsByOrg with filter of:" + passedParams.filter);
                return null;
            }
        }

Anything I'm missing here? I've been so close to this problem for a day now that I'm sure it's something simple so fresh eyes would be appreciated as I'm sole developer in the office! Many thanks for any advice.

Answer 1

Actually, this is not POST method. Do you have more methods in this controller?

Answer 2

OK. This isn't exactly an answer but hopefully my procedure to get it working might help someone. So I deleted the Web Service project and started again. Added a new project Asp.Net Web Application API. This automatically sets up a WebApiConfig.cs file in your App_Start folder. The route didn't work as it was set to routeTemplate: "api/{controller}/{id}", so I set it to routeTemplate: "api/{controller}/{action}/{id}",

You also get a ValuesController set up. Once the routing was changed, this then worked with the default GET and POST methods.

Next I added my GetServicesForSalon method. It still had the DefaultParams being passed in [FromBody] but instead of having int id {get;set;} declared I changed it to a string, eg string id {get;set;}

Hey presto, it worked.

I have just set up another controller(ServiceController) and copied the code into that to see what would happen. Identical apart from the name(obviously). It doesn't work. So https://localhost/OLBWebService/api/Values/GetServicesForSalon works. But. https://localhost/OLBWebService/api/Service/GetServicesForSalon doesn't work?

So it would seem you are limited to 1 controller which inherits the ApiController. No idea why this is but I now have multiple GET and POST methods working in the ValuesController which was set up by VS when I added the project.

Not ideal as I like to split out my methods according to objects, eg salon, staff, service, etc. But after wasting a day on this I'm just wanting to move on and make up some ground on lost time.