title: How to Deserialise JsonDocument To POCO Using System.Text.Json
body: <p>Using HttpClient I post a json document to my controller.</p>
  <pre><code>   public async Task&lt;string&gt; PostAsync&lt;T&gt;(string url, T doc)
     {
          var json = JsonConvert.SerializeObject(doc);
          var response = await mHttp.PostAsync(url, new StringContent(json));
     }
  </code></pre>
  <p>When I inspect the controller here:</p>
  <p><code>    public async Task&lt;ActionResult&gt; Post([FromBody] object doc,string fid)</code></p>
  <p>The object doc has this format:</p>
  <p><code>ValueKind = Object : &quot;{&quot;id&quot;: &quot;101zsdfgfgh&quot;,&quot;fid&quot;: &quot;test1&quot;,......</code>}</p>
  <p>How can  Ideserialize this if the type  is unknown?</p>