CODEWITHSUNDEEP
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Null Reference
Null Reference

Reputation: 11340

Property null when receiving on web api

I have the following method in my web api

public class AccessPanelController : ApiController
    {
        public HttpResponseMessage PostGrantAccess([FromUri]GrantAccessRequest grantAccessRequest)
        {
            var deviceId = grantAccessRequest.DeviceId;

            var grantAccessResponse = new GrantAccessResponse()
                {
                    Status = "OK"
                };
            var response = Request.CreateResponse<GrantAccessResponse>(HttpStatusCode.OK, grantAccessResponse);
            return response;
        }

    }

GrantAccessRequest class:

public class GrantAccessRequest
{
    public string DeviceId { get; set; }
}

Client:

  HttpClient client = new HttpClient();
            client.BaseAddress = new Uri("http://localhost:55208/");

            // Add an Accept header for JSON format.
            client.DefaultRequestHeaders.Accept.Add(
                new MediaTypeWithQualityHeaderValue("application/json"));

            Uri uri = null;

            var request = new GrantAccessRequest { DeviceId = "bla" };
            var response = client.PostAsJsonAsync("api/accesspanel", uri).Result;
            if (response.IsSuccessStatusCode)
            {
                uri = response.Headers.Location;
            }

In my PostGrantAccess method, grantAccessRequest is constructed, but DeviceId is null

Upvotes: 4

Views: 2348

Answers (2)

Darin Dimitrov
Darin Dimitrov

Reputation: 1038710

Get rid of the [FromUri] attribute on your controller action. Also on the client you don't seem to be doing anything with the request variable which is containing the payload:

public HttpResponseMessage PostGrantAccess(GrantAccessRequest grantAccessRequest)

To better understand how model binding works in the Web API I recommend you reading the following article.

So:

using (var client = new HttpClient())
{
    client.BaseAddress = new Uri("http://localhost:55208/");

    var request = new GrantAccessRequest { DeviceId = "bla" };
    var response = client.PostAsJsonAsync("api/accesspanel", request).Result;
    if (response.IsSuccessStatusCode)
    {
        var uri = response.Headers.Location;
    }
}

Notice that you don't need to set the Accept request header in this case because you are using the PostAsJsonAsync method.

Also I don't know if this is a typo in your question but you seem to have specified api/accesspanel as url whereas your controller action is called GrantAccessRequest.

Upvotes: 5

Jon Skeet
Jon Skeet

Reputation: 1499860

Well this looks problematic to start with:

Uri uri = null;
var request = new GrantAccessRequest { DeviceId = "bla" };
var response = client.PostAsJsonAsync("api/accesspanel", uri).Result;

You're never doing anything with request, and uri will always be null. How are you expecting the device ID to make it through to the server?

(I confess I don't know enough about WebAPI to know exactly how you're expected to fix this, but presumably you want to use request somewhere in the PostAsJsonAsync call... Given the [FromUri] attribute, I'd expect something to convert that data to part of the URI to use.)

Upvotes: 1

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