HttpClient不支持PostAsJsonAsync方法c#-HttpClientnotsupportingPostAsJsonAsyncmethodC#

282  

Yes, you need to add a reference to

是的，您需要添加一个引用到

System.Net.Http.Formatting.dll

This can be found in the extensions assemblies area.

这可以在扩展程序集区域中找到。

Note that a good way of achieving this is by adding the NuGet package System.Net.Http.Formatting.Extension to your project.

注意，实现这一点的一个好方法是添加NuGet包System.Net.Http.Formatting。扩展您的项目。

120  

The missing reference is the System.Net.Http.Formatting.dll. But the better solution is to add the NuGet package Microsoft.AspNet.WebApi.Client to ensure the version of the formatting dll worked with the .NET framework version of System.Net.Http in my project.

缺少的引用是System.Net.Http.Formatting.dll。但是更好的解决方案是添加NuGet包Microsoft.AspNet.WebApi。客户端确保格式化dll的版本与。net框架版本的System.Net兼容。在我的项目Http。

112  

PostAsJsonAsync is no longer in the System.Net.Http.dll (.NET 4.5.2). You can add a reference to System.Net.Http.Formatting.dll, but this actually belongs to an older version. I ran into problems with this on our TeamCity build server, these two wouldn't cooperate together.

PostAsJsonAsync不在System.Net.Http中。dll(。净4.5.2)。您可以添加对system . net . http . format的引用。dll，但它实际上属于一个旧版本。我在我们的TeamCity构建服务器上遇到了这个问题，这两个不能一起合作。

Alternatively, you can replace PostAsJsonAsyncwith a PostAsync call, which is just part of new dll. Replace

或者，您可以用postasjsonasync调用替换postasjsonasync，后者只是新dll的一部分。取代

var respOnse= client.PostAsJsonAsync("api/AgentCollection", user).Result;

With:

:

var respOnse= client.PostAsync("api/AgentCollection", new StringContent(
   new JavascriptSerializer().Serialize(user), Encoding.UTF8, "application/json")).Result;

See https://code.msdn.microsoft.com/windowsapps/How-to-use-HttpClient-to-b9289836

参见https://code.msdn.microsoft.com/windowsapps/How-to-use-HttpClient-to-b9289836

21  

As already debatted, this method isn't available anymore since .NET 4.5.2. To expand on Jeroen K's answer you can make an extension method:

由于已经进行了debatted，所以这个方法在。net 4.5.2之后就不再可用了。要扩展耶罗文K的答案，可以使用扩展方法:

public static async Task PostAsJsonAsync(this HttpClient client, string requestUrl, TModel model)
{
    var serializer = new JavascriptSerializer();
    var json = serializer.Serialize(model);
    var stringCOntent= new StringContent(json, Encoding.UTF8, "application/json");
    return await client.PostAsync(requestUrl, stringContent);
}

Now you are able to call client.PostAsJsonAsync("api/AgentCollection", user).

现在您可以调用客户机了。PostAsJsonAsync(“api / AgentCollection”、用户)。

6  

I had this issue too on a project I'd just checked out from source control.

在我刚刚从源代码控制中检出的一个项目中，我也遇到了这个问题。

The symptom was the error described above and a yellow warning triangle on a reference to System.Net.Http.Formatting

症状是上面描述的错误和system . net . http . format的一个黄色警告三角形

To fix this, I removed the broken reference and then used NuGet to install the latest version of Microsoft.AspNet.WebApi.Client.

为了解决这个问题，我删除了被破坏的引用，然后使用NuGet安装了最新版本的Microsoft.AspNet.WebApi.Client。

2  

Instead of writing this amount of code to make a simple call, you could use one of the wrappers available over the internet.

不用编写这么多代码来进行简单的调用，您可以使用internet上可用的一个包装器。

I've written one called WebApiClient, available at NuGet... check it out!

我写了一篇叫做WebApiClient的文章，在NuGet上可以找到。点击这里查看详情！

http://webapiclient.azurewebsites.net

http://webapiclient.azurewebsites.net

2  

I know this reply is too late, I had the same issue and i was adding the System.Net.Http.Formatting.Extension Nuget, after checking here and there I found that the Nuget is added but the System.Net.Http.Formatting.dll was not added to the references, I just reinstalled the Nuget

我知道这个回复太晚了，我遇到了同样的问题，我添加了System.Net.Http.Formatting。扩展Nuget，在这里和那里检查之后，我发现添加了Nuget，但是添加了system . net . http . format。dll没有添加到引用中，我只是重新安装了Nuget