读取 WebApi 控制器中的 HttpContent

如何在 MVCwebApi 控制器操作中读取 PUT 请求上的内容。

[HttpPut]
public HttpResponseMessage Put(int accountId, Contact contact)
{
var httpContent = Request.Content;
var asyncContent = httpContent.ReadAsStringAsync().Result;
...

我在这里得到了空字符串: (

我需要做的是: 弄清楚在初始请求中修改/发送了“哪些属性”(这意味着如果 Contact对象有10个属性，而我只想更新其中的2个，那么我发送和发送对象时只有两个属性，类似下面这样:

{


"FirstName": null,
"LastName": null,
"id": 21
}

预期的最终结果是

List<string> modified_properties = {"FirstName", "LastName"}
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最佳答案

By design the body content in ASP.NET Web API is treated as forward-only stream that can be read only once.

The first read in your case is being done when Web API is binding your model, after that the Request.Content will not return anything.

You can remove the contact from your action parameters, get the content and deserialize it manually into object (for example with Json.NET):

[HttpPut]
public HttpResponseMessage Put(int accountId)
{
HttpContent requestContent = Request.Content;
string jsonContent = requestContent.ReadAsStringAsync().Result;
CONTACT contact = JsonConvert.DeserializeObject<CONTACT>(jsonContent);
...
}

That should do the trick (assuming that accountId is URL parameter so it will not be treated as content read).

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You can keep your CONTACT parameter with the following approach:

using (var stream = new MemoryStream())
{
var context = (HttpContextBase)Request.Properties["MS_HttpContext"];
context.Request.InputStream.Seek(0, SeekOrigin.Begin);
context.Request.InputStream.CopyTo(stream);
string requestBody = Encoding.UTF8.GetString(stream.ToArray());
}

Returned for me the json representation of my parameter object, so I could use it for exception handling and logging.

Found as accepted answer here

小开

Even though this solution might seem obvious, I just wanted to post it here so the next guy will google it faster.

If you still want to have the model as a parameter in the method, you can create a DelegatingHandler to buffer the content.

internal sealed class BufferizingHandler : DelegatingHandler
{
protected override async Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, CancellationToken cancellationToken)
{
await request.Content.LoadIntoBufferAsync();
var result = await base.SendAsync(request, cancellationToken);
return result;
}
}

And add it to the global message handlers:

configuration.MessageHandlers.Add(new BufferizingHandler());

This solution is based on the answer by Darrel Miller.

This way all the requests will be buffered.


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