title: How can I query Algolia to find all documents missing a particular key?
body: <p>If I have an Algolia index containing documents that look like these:<br><br></p>
  
  <pre><code>{"object_id":1, "color":"red", "shape":"circle"}
  {"object_id":2, "color":"blue", "shape":"triangle"}
  {"object_id":3, "color":"green", "shape":"square"}
  {"object_id":4, "color":null, "shape":"hexagon"}
  {"object_id":5, "shape":"hexagon"}
  ...
  </code></pre>
  
  <p>Using the python API for Algolia, how can I search the index to get objects like 4 and 5 back since they are both missing the "color" attribute.<br><br>I've been dragging through (<a href="https://www.algolia.com/doc/api-client/python/search#search-in-an-index" rel="nofollow noreferrer">https://www.algolia.com/doc/api-client/python/search#search-in-an-index</a>) but I cannot find the answer.<br><br></p>
  
  <p>I've tried this snippet but no luck:<br></p>
  
  <pre><code>from algoliasearch import algoliasearch
  
  client = algoliasearch.Client("YourApplicationID", 'YourAPIKey')
  index = client.init_index("colorful_shapes")
  res = index.search("null")
  res1 = index.search("color=null")
  res2 = index.search("color:null")
  res3 = index.search("!color")
  print(res, res1, res2, res3)
  </code></pre>