如何使用 System.Net.HttpClient 发布复杂类型？

我有一个自定义的复杂类型，我想使用 Web API 来处理它。

public class Widget
{
public int ID { get; set; }
public string Name { get; set; }
public decimal Price { get; set; }
}

这是我的 web API 控制器方法，我想像这样发布这个对象:

public class TestController : ApiController
{
// POST /api/test
public HttpResponseMessage<Widget> Post(Widget widget)
{
widget.ID = 1; // hardcoded for now. TODO: Save to db and return newly created ID


var response = new HttpResponseMessage<Widget>(widget, HttpStatusCode.Created);
response.Headers.Location = new Uri(Request.RequestUri, "/api/test/" + widget.ID.ToString());
return response;
}
}

现在我想用 System.Net.HttpClient调用这个方法。但是，我不确定要传递给 PostAsync方法的对象类型，以及如何构造它。下面是一些示例客户端代码。

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) =>
{
postTask.Result.EnsureSuccessStatusCode();
});

我如何创建 HttpContent对象的方式，Web API 将理解它？

210942 次浏览
小开

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<Widget>(widget))
.ContinueWith((postTask) => 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<KeyValuePair<string, string>>();
postData.Add(new KeyValuePair<string, string>("Name", "test"));
postData.Add(new KeyValuePair<string, string>("Price ", "100"));


HttpContent content = new FormUrlEncodedContent(postData);


client.PostAsync("http://localhost:44268/api/test", content).ContinueWith(
(postTask) =>
{
postTask.Result.EnsureSuccessStatusCode();
});

Note: you need to make your id to a nullable int (int?)

小开
最佳答案

The generic HttpRequestMessage<T> has been removed. This :

new HttpRequestMessage<Widget>(widget)

will no longer work.

Instead, from this post, the ASP.NET team has included some new calls to support this functionality:

HttpClient.PostAsJsonAsync<T>(T value) sends “application/json”
HttpClient.PostAsXmlAsync<T>(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) => postTask.Result.EnsureSuccessStatusCode() );
小开

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) => postTask.Result.EnsureSuccessStatusCode());
小开

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<T>();
dynamic d = await url.PostUrlEncodedAsync(data).ReceiveJson();
string s = await url.PostUrlEncodedAsync(data).ReceiveString();

Flurl is available on NuGet:

PM> Install-Package Flurl.Http
小开

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

小开

I think you can do this:

var client = new HttpClient();
HttpContent content = new Widget();
client.PostAsync<Widget>("http://localhost:44268/api/test", content, new FormUrlEncodedMediaTypeFormatter())
.ContinueWith((postTask) => { postTask.Result.EnsureSuccessStatusCode(); });
小开

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

小开

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<HttpResponseMessage> response = httpClient.PostAsJsonAsync(
strMyHttpPostURL,
new MyComplexObject { Param1 = param1, Param2 = param2}).ContinueWith((postTask) => postTask.Result.EnsureSuccessStatusCode());
//debug:
//String s = response.Result.Content.ReadAsStringAsync().Result;
MyOtherComplexType moct = (MyOtherComplexType)JsonConvert.DeserializeObject(response.Result.Content.ReadAsStringAsync().Result, typeof(MyOtherComplexType));
小开

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<Address>().Result : null;
return dataObjects;
}

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