如何使用System.Net.HttpClient发布复杂类型？

Question

我有一个自定义复杂类型,我想使用Web API.

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;
    }
}

现在我想使用System.Net.HttpClient来调用该方法.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.这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();
    });

如何以Web API理解的方式创建HttpContent对象？

Answer 1

该通用HttpRequestMessage<T>已被删除.这个 :

new HttpRequestMessage<Widget>(widget)

将不再有效.

相反,从这篇文章中,ASP.NET团队已经包含了一些新的调用来支持这个功能:

HttpClient.PostAsJsonAsync<T>(T value) sends “application/json”
HttpClient.PostAsXmlAsync<T>(T value) sends “application/xml”

所以,新代码(来自dunston)变成:

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() );

Answer 2

您应该使用该SendAsync方法,这是一种通用方法,它将服务的输入序列化

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() );

如果您不想创建具体类,可以使用FormUrlEncodedContent该类创建

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();
    });

注意:你需要将你的id设置为可以为null的int(int?)

Answer 3

请注意,如果您使用的是可移植类库,则HttpClient将不具有PostAsJsonAsync方法.要使用可移植类库将内容发布为JSON,您必须执行以下操作:

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());