title: How to pass data to urllib3 POST request method?
body: <p>I want to use <code>urllib3</code> library for making POST request over <code>requests</code> library since it has connection pooling and retries etc. But I couldn't 
  find any substitute of following <code>POST</code> request.</p>
  
  <pre><code>import requests
  result = requests.post("http://myhost:8000/api/v1/edges", json={'node_id1':"VLTTKeV-ixhcGgq53", 'node_id2':"VLTTKeV-ixhcGgq51", 'type': 1 })
  </code></pre>
  
  <p>This is working fine with <code>requests</code> library but I couldn't convert this into <code>urllib3</code> request.
  I tried</p>
  
  <pre><code>import json
  import urllib3
  urllib3.PoolManager().request("POST","http://myhost:8000/api/v1/edges", body=json.dumps(dict(json={'node_id1':"VLTTKeV-ixhcGgq53", 'node_id2':"VLTTKeV-ixhcGgq51", 'type': 1 })))
  </code></pre>
  
  <p>Problem is with passing raw json data with <code>json</code> as key in <code>POST</code> request. </p>