How to use System Net HttpClient to post a complex type

Question

I have a custom complex type that I want to work with using Web API   public class Widget       public int ID   get  set        public string Name   get  set        public decimal Price   get  set        And here is my web API controller method  I want to post this object like so   public class TestController   ApiController          POST  api test     public HttpResponseMessage lt Widget gt  Post Widget widget                widget ID   1     hardcoded for now  TODO  Save to db and return newly created ID          var response   new HttpResponseMessage lt Widget gt  widget  HttpStatusCode Created           response Headers Location   new Uri Request RequestUri    api test     widget ID ToString             return response            And now I d like to use System Net HttpClient to make the call to the method  However  I m unsure of what type of object to pass into the PostAsync method  and how to construct it  Here is some sample client code    var client   new HttpClient    HttpContent content   new StringContent            how do I construct the Widget to post  client PostAsync  http   localhost 44268 api test   content  ContinueWith       postTask    gt                postTask Result EnsureSuccessStatusCode              How do I create the HttpContent object in a way that web API will understand it

User · Answer

After investigating lots of alternatives, I have come across another approach, suitable for the API 2.0 version.

(VB.NET is my favorite, sooo...)

Public Async Function APIPut_Response(ID as Integer, MyWidget as Widget) as Task(Of HttpResponseMessage)
    Dim DesiredContent as HttpContent = New StringContent(JsonConvert.SerializeObject(MyWidget))
    Return Await APIClient.PutAsync(String.Format("api/widget/{0}", ID), DesiredContent)
End Function

Good luck! For me this worked out (in the end!).

Regards, Peter

User · Answer

Note that if you are using a Portable Class Library  HttpClient will not have PostAsJsonAsync method  To post a content as JSON using a Portable Class Library  you will have to do this    HttpClient client   new HttpClient    HttpContent contentPost   new StringContent argsAsJson  Encoding UTF8    application json     await client PostAsync new Uri wsUrl   contentPost  ContinueWith   postTask    gt  postTask Result EnsureSuccessStatusCode

User · Answer

Make a service call like this   public async void SaveActivationCode ActivationCodes objAC        var client   new HttpClient        client BaseAddress   new Uri baseAddress       HttpResponseMessage response   await client PutAsJsonAsync serviceAddress     SaveActivationCode      apiKey 445-65-1216   objAC        And Service method like this   public HttpResponseMessage PutSaveActivationCode ActivationCodes objAC        PutAsJsonAsync takes care of Serialization and deserialization over the network

User · Answer

I think you can do this   var client   new HttpClient    HttpContent content   new Widget    client PostAsync lt Widget gt   http   localhost 44268 api test   content  new FormUrlEncodedMediaTypeFormatter         ContinueWith  postTask    gt    postTask Result EnsureSuccessStatusCode

User · Answer

If you want the types of convenience methods mentioned in other answers but need portability  or even if you don t   you might want to check out Flurl  disclosure  I m the author   It  thinly  wraps HttpClient and Json NET and adds some fluent sugar and other goodies  including some baked-in testing helpers   Post as JSON   var resp   await  http   localhost 44268 api test  PostJsonAsync widget     or URL-encoded   var resp   await  http   localhost 44268 api test  PostUrlEncodedAsync widget     Both examples above return an HttpResponseMessage  but Flurl includes extension methods for returning other things if you just want to cut to the chase   T poco   await url PostJsonAsync data  ReceiveJson lt T gt     dynamic d   await url PostUrlEncodedAsync data  ReceiveJson    string s   await url PostUrlEncodedAsync data  ReceiveString      Flurl is available on NuGet   PM gt  Install-Package Flurl Http

User · Answer

In case someone like me didn t really understand what all above are talking about  I give an easy example which is working for me  If you have a web api which url is  http   somesite com verifyAddress   it is a post method and it need you to pass it an address object  You want to call this api in your code  Here what you can do       public Address verifyAddress Address address                this client   new HttpClient            client BaseAddress   new Uri  http   somesite com             client DefaultRequestHeaders Accept Add new MediaTypeWithQualityHeaderValue  application json             var urlParm   URL    verifyAddress           response   client PostAsJsonAsync urlParm address  Result          var dataObjects   response IsSuccessStatusCode   response Content ReadAsAsync lt Address gt    Result   null          return dataObjects

User · Answer

The generic HttpRequestMessage lt T gt  has been removed  This    new HttpRequestMessage lt Widget gt  widget    will no longer work   Instead  from this post  the ASP NET team has included some new calls to support this functionality   HttpClient PostAsJsonAsync lt T gt  T value  sends    application json    HttpClient PostAsXmlAsync lt T gt  T value  sends    application xml      So  the new code  from dunston  becomes   Widget widget   new Widget   widget Name    test  widget Price   1   HttpClient client   new HttpClient    client BaseAddress   new Uri  http   localhost 44268    client PostAsJsonAsync  api test   widget       ContinueWith  postTask    gt  postTask Result EnsureSuccessStatusCode

User · Answer

You should use the SendAsync method instead  this is a generic method  that serializes the input to the service  Widget widget   new Widget   widget Name    test  widget Price   1   HttpClient client   new HttpClient    client BaseAddress   new Uri  http   localhost 44268 api test    client SendAsync new HttpRequestMessage lt Widget gt  widget        ContinueWith  postTask    gt  postTask Result EnsureSuccessStatusCode        If you don t want to create the concrete class  you can make it with the FormUrlEncodedContent class  var client   new HttpClient        This is the postdata var postData   new List lt KeyValuePair lt string  string gt  gt     postData Add new KeyValuePair lt string  string gt   Name    test     postData Add new KeyValuePair lt string  string gt   Price     100      HttpContent content   new FormUrlEncodedContent postData     client PostAsync  http   localhost 44268 api test   content  ContinueWith       postTask    gt                postTask Result EnsureSuccessStatusCode              Note  you need to make your id to a nullable int  int

User · Answer

This is the code I wound up with  based upon the other answers here  This is for an HttpPost that receives and responds with complex types   Task lt HttpResponseMessage gt  response   httpClient PostAsJsonAsync                         strMyHttpPostURL                         new MyComplexObject   Param1   param1  Param2   param2   ContinueWith  postTask    gt  postTask Result EnsureSuccessStatusCode                           debug                        String s   response Result Content ReadAsStringAsync   Result                      MyOtherComplexType moct    MyOtherComplexType JsonConvert DeserializeObject response Result Content ReadAsStringAsync   Result  typeof MyOtherComplexType

[c#] How to use System.Net.HttpClient to post a complex type?

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