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The API I'm trying to call requires a POST with an empty body. I'm using the WCF Web API HttpClient, and I can't find the right code that will post with an empty body. I found references to some HttpContent.CreateEmpty() method, but I don't think it’s for the Web API HttpClient code since I can't seem to find that method.

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4

8 Answers 8

Reset to default
284

Use StringContent or ObjectContent which derive from HttpContent or you can use null as HttpContent:

var response = await client.PostAsync(requestUri, null);
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9 Comments

It looks like this is only in .NET framework 4.5? msdn.microsoft.com/en-us/library/…
It will ship with WCF Web API but I think some of the "good parts" will make it into the framework itself.
Why isn't there any overload methods which does not require a HttpContent class? Should we at least provide something (even an empty string) to make a http post?
You can use null as the HttpContent, this will send no body in the request, e.g. var response = await client.PostAsync(requestUri, null);
Assembly System.Net.Http in version 5.0.0.0 has still no nullable HttpContent parameter, so null should be not allowed. But it (still) seems to work. I could pass null!.
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137

Did this before, just keep it simple: 

Task<HttpResponseMessage> task = client.PostAsync(url, null);
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1 Comment

This is cleaner than accepted answer, and should be voted up.
14

Have found that:

Task<HttpResponseMessage> task = client.PostAsync(url, null);

Adds null to the request body, which failed on WSO2. Replaced with:

Task<HttpResponseMessage> task = client.PostAsync(url, new {});

And worked.

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1 Comment

I cannot confirm this finding (but I am not sure my test was totally adequate). When I POST to one of my own APIs with a null content and look at the content found in the HttpRequestMessage, I seem to be getting a length of zero bytes.
2

In case you do not want to pass null value you can you the following:

Task<HttpResponseMessage> task = httpClient.PostAsync(uri, new StringContent(String.Empty));

But, beside this, as above already discussed you could pass null in there as a parameter.

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2

If you wish to avoid 'null' and make your intentions clear, as do I, you can override the StringContent class:

    private sealed class DeliberatelyEmptyContent : StringContent
    {
        public DeliberatelyEmptyContent() : base(string.Empty)
        {
        }
    }

    public async Task ActivateUser(string xflowUserId)
    {
        var httpclient = _httpClientFactory.CreateClient(_namedHttpClientName);
        string activateUrl = $"/User/{xflowUserId}/Activate";

        _ = await httpclient.PutAsync(activateUrl, new DeliberatelyEmptyContent());
    }
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1

To solve this problem, use this example:

   using (var client = new HttpClient())
            {
                var stringContent = new StringContent(string.Empty);
                stringContent.Headers.ContentType = MediaTypeHeaderValue.Parse("application/x-www-form-urlencoded");
                var response = client.PostAsync(url, stringContent).Result;
                var result = response.Content.ReadAsAsync<model>().Result;
            }
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0

You can send an empty object too:

var emptyObject = new object();
HttpResponseMessage httpResponse = await server.CreateClient().PutAsJsonAsync(Put.SomeUrl(), emptyObject);
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-6

I think it does that automagically if your web method has no parameters or they all fit into URL template.

For example this declaration sends empty body:

  [OperationContract]
  [WebGet(UriTemplate = "mykewlservice/{emailAddress}",
     RequestFormat = WebMessageFormat.Json, ResponseFormat = WebMessageFormat.Json,
     BodyStyle = WebMessageBodyStyle.Wrapped)]
  void GetStatus(string emailAddress, out long statusMask);
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3 Comments

I'm trying to SEND an empty body. The HttpClient.Post() method requires an URI and a HttpContent object. I'm not what to pass as the HttpContent when I don't want to send anything.
So you're not using WCF. That's even easier: ... HttpWebRequest request = (HttpWebRequest) WebRequest.Create("http://..."); request.Method = "POST"; HttpWebResponse respose = (HttpWebResponse)request.GetResponse(); ... you result in response
I'm using HttpClient, not HttpWebRequest. Using StringContent with an empty string worked.

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