blocks|key|4421533|text|您需要在请求正文中以原始字符串而不是FormUrlEncodedContent的形式传递数据。一种方法是将其序列化为JSON字符串：|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|4421534|var+json+=+JsonConvert.SerializeObject(data);+//+or+JsonSerializer.Serialize+if+using+System.Text.Json|code-block|syntax|javascript|4421535|现在，您需要做的就是将字符串传递给post方法。|4421536|var+stringContent+=+new+StringContent(json,+UnicodeEncoding.UTF8,+"application/json");+//+use+MediaTypeNames.Application.Json+in+Core+3.0%2B+and+Standard+2.1%2B

var+client+=+new+HttpClient();
var+response+=+await+client.PostAsync(uri,+stringContent);|4421537|entityMap^0|I|L|0|0|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@$9|R|A|S|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|T|8|@]|D|@]|E|$I|J]]|$1|K|3|L|5|6|7|U|8|@]|D|@]|E|$]]|$1|M|3|N|5|H|7|V|8|@]|D|@]|E|$I|J]]|$1|O|3|-4|5|6|7|W|8|@]|D|@]|E|$]]]|P|$]]

You need to pass your data in the request body as a raw string rather than <code>FormUrlEncodedContent</code>. One way to do so is to serialize it into a JSON string:

<pre><code>var json = JsonConvert.SerializeObject(data); // or JsonSerializer.Serialize if using System.Text.Json
</code></pre>

Now all you need to do is pass the string to the post method.

<pre><code>var stringContent = new StringContent(json, UnicodeEncoding.UTF8, "application/json"); // use MediaTypeNames.Application.Json in Core 3.0+ and Standard 2.1+

var client = new HttpClient();
var response = await client.PostAsync(uri, stringContent);
</code></pre>

blocks|key|4421744|text|一个简单的解决方案是使用NuGet中的Microsoft+ASP.NET+Web+API+2.2+Client。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|4421745|然后，您可以简单地执行此操作，它会将对象序列化为JSON，并将Content-Type标头设置为application/json;+charset=utf-8|4421746|var+data+=+new
{
++++name+=+"Foo",
++++category+=+"article"
};

var+client+=+new+HttpClient();
client.BaseAddress+=+new+Uri(baseUri);
client.DefaultRequestHeaders.Add("token",+token);
var+response+=+await+client.PostAsJsonAsync("",+data);|code-block|syntax|javascript|4421747|entityMap|0|LINK|mutability|MUTABLE|url|https://www.nuget.org/packages/microsoft.aspnet.webapi.client/^0|J|10|C|5|0|0|V|C|1C|V|0|0^^$0|@$1|2|3|4|5|6|7|U|8|@$9|V|A|W|B|C]]|D|@$9|X|A|Y|1|Z]]|E|$]]|$1|F|3|G|5|6|7|10|8|@$9|11|A|12|B|C]|$9|13|A|14|B|C]]|D|@]|E|$]]|$1|H|3|I|5|J|7|15|8|@]|D|@]|E|$K|L]]|$1|M|3|-4|5|6|7|16|8|@]|D|@]|E|$]]]|N|$O|$5|P|Q|R|E|$S|T]]]]

A simple solution is to use <code>Microsoft ASP.NET Web API 2.2 Client</code> from <a href="https://www.nuget.org/packages/microsoft.aspnet.webapi.client/" rel="noreferrer">NuGet</a>.

Then you can simply do this and it'll serialize the object to JSON and set the <code>Content-Type</code> header to <code>application/json; charset=utf-8</code>:

<pre><code>var data = new
{
 name = "Foo",
 category = "article"
};

var client = new HttpClient();
client.BaseAddress = new Uri(baseUri);
client.DefaultRequestHeaders.Add("token", token);
var response = await client.PostAsJsonAsync("", data);
</code></pre>

blocks|key|4421813|text|新的.NET+5解决方案：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|4421814|在.NET+5中，引入了一个名为JsonContent的新类，它是从HttpContent派生的。See+in+Microsoft+docs|offset|length|style|CODE|4421815|该类包含一个名为Create()的静态方法，它接受任意对象作为参数，顾名思义，它返回JsonContent的一个实例，然后可以将该实例作为参数传递给PostAsync方法。|4421816|用法：|4421817|var+myObject+=+new
{
++++foo+=+"Hello",
++++bar+=+"World",
};

JsonContent+content+=+JsonContent.Create(myObject);

HttpResponseMessage+response+=+await+_httpClient.PostAsync("https://...",+content);|code-block|syntax|javascript|4421818|entityMap|0|LINK|mutability|MUTABLE|url|https://docs.microsoft.com/en-us/dotnet/api/system.net.http.json.jsoncontent?view=net-5.0^0|0|G|B|Y|B|1D|L|0|0|8|8|16|B|22|9|0|0|0^^$0|@$1|2|3|4|5|6|7|Y|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|Z|8|@$D|10|E|11|F|G]|$D|12|E|13|F|G]]|9|@$D|14|E|15|1|16]]|A|$]]|$1|H|3|I|5|6|7|17|8|@$D|18|E|19|F|G]|$D|1A|E|1B|F|G]|$D|1C|E|1D|F|G]]|9|@]|A|$]]|$1|J|3|K|5|6|7|1E|8|@]|9|@]|A|$]]|$1|L|3|M|5|N|7|1F|8|@]|9|@]|A|$O|P]]|$1|Q|3|-4|5|6|7|1G|8|@]|9|@]|A|$]]]|R|$S|$5|T|U|V|A|$W|X]]]]

<h1>New .NET 5 Solution:</h1>
In .NET 5, a new class has been introduced called <code>JsonContent</code>, which derives from <code>HttpContent</code>. <a href="https://docs.microsoft.com/en-us/dotnet/api/system.net.http.json.jsoncontent?view=net-5.0" rel="nofollow noreferrer">See in Microsoft docs</a>
This class contains a static method called <code>Create()</code>, which takes any arbitrary object as a parameter, and as the name implies returns an instance of <code>JsonContent</code>, which you can then pass as an argument to the <code>PostAsync</code> method.
Usage:
<pre><code>var myObject = new
{
 foo = &quot;Hello&quot;,
 bar = &quot;World&quot;,
};

JsonContent content = JsonContent.Create(myObject);

HttpResponseMessage response = await _httpClient.PostAsync(&quot;https://...&quot;, content);
</code></pre>

blocks|key|4421718|text|@arad很好的观点。事实上，我只是发现了这个扩展方法(.NET+5.0)：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|4421719|PostAsJsonAsync<TValue>(HttpClient,+String,+TValue,+CancellationToken)|offset|length|style|CODE|4421720|来自https://docs.microsoft.com/en-us/dotnet/api/system.net.http.json.httpclientjsonextensions.postasjsonasync?view=net-5.0|4421721|所以现在我们可以：|4421722|var+data+=+new+{+foo+=+"Hello";+bar+=+42;+};
var+response+=+await+_Client.PostAsJsonAsync(_Uri,+data,+cancellationToken);|code-block|syntax|javascript|4421723|entityMap|0|LINK|mutability|MUTABLE|url|https://docs.microsoft.com/en-us/dotnet/api/system.net.http.json.httpclientjsonextensions.postasjsonasync?view=net-5.0^0|0|0|1Y|0|2|3A|0|0|0|0^^$0|@$1|2|3|4|5|6|7|Y|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|Z|8|@$D|10|E|11|F|G]]|9|@]|A|$]]|$1|H|3|I|5|6|7|12|8|@]|9|@$D|13|E|14|1|15]]|A|$]]|$1|J|3|K|5|6|7|16|8|@]|9|@]|A|$]]|$1|L|3|M|5|N|7|17|8|@]|9|@]|A|$O|P]]|$1|Q|3|-4|5|6|7|18|8|@]|9|@]|A|$]]]|R|$S|$5|T|U|V|A|$W|X]]]]

@arad good point. In fact I just found this extension method (.NET 5.0):
<code>PostAsJsonAsync&lt;TValue&gt;(HttpClient, String, TValue, CancellationToken)</code>
from <a href="https://docs.microsoft.com/en-us/dotnet/api/system.net.http.json.httpclientjsonextensions.postasjsonasync?view=net-5.0" rel="noreferrer">https://docs.microsoft.com/en-us/dotnet/api/system.net.http.json.httpclientjsonextensions.postasjsonasync?view=net-5.0</a>
So one can now:
<pre><code>var data = new { foo = &quot;Hello&quot;; bar = 42; };
var response = await _Client.PostAsJsonAsync(_Uri, data, cancellationToken);
</code></pre>

blocks|key|4421894|text|根据您编写的框架，您有两个选择，如果您使用的是.Net+5，则可以只执行JsonContent.Create(yourObject);|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|4421895|或者创建和扩展方法并在您的对象上调用它：|4421896|public+static+StringContent+GetStringContent(this+object+obj)
{
++++var+jsonContent+=+JsonConvert.SerializeObject(obj);
++++var+contentString+=+new+StringContent(jsonContent,+Encoding.UTF8,+"application/json");
++++contentString.Headers.ContentType+=+new+MediaTypeHeaderValue("application/json");

++++return+contentString;
}|code-block|syntax|javascript|4421897|entityMap^0|10|V|0|0|0^^$0|@$1|2|3|4|5|6|7|O|8|@$9|P|A|Q|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|R|8|@]|D|@]|E|$]]|$1|H|3|I|5|J|7|S|8|@]|D|@]|E|$K|L]]|$1|M|3|-4|5|6|7|T|8|@]|D|@]|E|$]]]|N|$]]

You have two options depending on which framework are you coding, you could just do <code>JsonContent.Create(yourObject);</code> if you are on .Net 5
or create and extension method and call it on your object:
<pre><code>public static StringContent GetStringContent(this object obj)
{
 var jsonContent = JsonConvert.SerializeObject(obj);
 var contentString = new StringContent(jsonContent, Encoding.UTF8, &quot;application/json&quot;);
 contentString.Headers.ContentType = new MediaTypeHeaderValue(&quot;application/json&quot;);

 return contentString;
}
</code></pre>

blocks|key|4421796|text|public+static+async+Task<string>+Post(string+param,+string+code,+string+subject,+string+description)
++++{
++++++++object+mydata+=+new
++++++++{
++++++++++++code+=+code,
++++++++++++subject+=+subject,
++++++++++++description+=+description
++++++++};
++++++++var+myContent+=+JsonConvert.SerializeObject(mydata);
++++++++var+buffer+=+System.Text.Encoding.UTF8.GetBytes(myContent);
++++++++var+byteContent+=+new+ByteArrayContent(buffer);
++++++++byteContent.Headers.ContentType+=+new+MediaTypeHeaderValue("application/json");

++++++++using+(HttpClient+client+=+new+HttpClient())
++++++++{
++++++++++++using+(HttpResponseMessage+res+=+await+client.PostAsync(baseURL+%2B+param,+byteContent))
++++++++++++{
++++++++++++++++Console.WriteLine("Nico",+res);
++++++++++++++++using+(HttpContent+content+=+res.Content)
++++++++++++++++{
++++++++++++++++++++string+data+=+await+content.ReadAsStringAsync();
++++++++++++++++++++if+(data+!=+null)+{+return+data;+}
++++++++++++++++}
++++++++++++}
++++++++}
++++++++return+string.Empty;
++++}|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|4421797|在我的其他形式中|unstyled|4421798|private+async+void+button2_Click(object+sender,+EventArgs+e)+//POST
++++++++{
++++++++++++string+param+=+"subject";
++++++++++++string+code+=+txtCode.Text;+//NC101
++++++++++++string+subject+=+txtSubject.Text;
++++++++++++string+description+=+txtDescription.Text;
++++++++++++var+res+=+await+RESTHelper.Post(param,+code,+subject,+description);
++++++++++++txtRes.Text+=+res;
++++++++}|4421799|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|K|8|@]|9|@]|A|$B|C]]|$1|D|3|E|5|F|7|L|8|@]|9|@]|A|$]]|$1|G|3|H|5|6|7|M|8|@]|9|@]|A|$B|C]]|$1|I|3|-4|5|F|7|N|8|@]|9|@]|A|$]]]|J|$]]

<pre><code>public static async Task&lt;string&gt; Post(string param, string code, string subject, string description)
 {
 object mydata = new
 {
 code = code,
 subject = subject,
 description = description
 };
 var myContent = JsonConvert.SerializeObject(mydata);
 var buffer = System.Text.Encoding.UTF8.GetBytes(myContent);
 var byteContent = new ByteArrayContent(buffer);
 byteContent.Headers.ContentType = new MediaTypeHeaderValue(&quot;application/json&quot;);

 using (HttpClient client = new HttpClient())
 {
 using (HttpResponseMessage res = await client.PostAsync(baseURL + param, byteContent))
 {
 Console.WriteLine(&quot;Nico&quot;, res);
 using (HttpContent content = res.Content)
 {
 string data = await content.ReadAsStringAsync();
 if (data != null) { return data; }
 }
 }
 }
 return string.Empty;
 }
</code></pre>
in my other form
<pre><code>private async void button2_Click(object sender, EventArgs e) //POST
 {
 string param = &quot;subject&quot;;
 string code = txtCode.Text; //NC101
 string subject = txtSubject.Text;
 string description = txtDescription.Text;
 var res = await RESTHelper.Post(param, code, subject, description);
 txtRes.Text = res;
 }
</code></pre>

I'm using <code>System.Net.Http</code>, I found several examples on the web. I managed to create this code for make a <code>POST</code> request:

<pre><code>public static string POST(string resource, string token)
{
 using (var client = new HttpClient())
 {
 client.BaseAddress = new Uri(baseUri);
 client.DefaultRequestHeaders.Add("token", token);

 var content = new FormUrlEncodedContent(new[]
 {
 new KeyValuePair&lt;string, string&gt;("", "")
 });

 var result = client.PostAsync("", content).Result;
 string resultContent = result.Content.ReadAsStringAsync().Result;
 return resultContent;
 }
 }
</code></pre>

all working fine. But suppose that I want pass a third param to the <code>POST</code> method, a param called <code>data</code>. The data param is an object like this:

<pre><code>object data = new
{
 name = "Foo",
 category = "article"
};
</code></pre>

how can I do that without create the <code>KeyValuePair</code>? My php <code>RestAPI</code> wait a json input, so the <code>FormUrlEncodedContent</code> should send the <code>raw</code> json correctly. But how can I do this with <code>Microsoft.Net.Http</code>? Thanks.

How do I pass an object to HttpClient.PostAsync and serialize as a JSON body?

JSON

我正在使用System.Net.Http，我在网上找到了几个例子。我设法创建了用于发出POST请求的代码：public static string POST(string resource, string token){    using (var client = new HttpClient())    {    ...

问如何将对象传递给HttpClient.PostAsync并将其序列化为JSON体？
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