title: Building an ElasticSearch search with exists using pyes
body: <p>The goal of this example code is to figure out how to create a query consisting out of multiple filters and queries.</p>
  
  <p>The below example is not working as expected.</p>
  
  <ol>
  <li>I want to be able to execute my search only on document which contain a certain "key".  That what I'm trying to reach with the ExistsFilter, but when enabling I don't get any results back.</li>
  </ol>
  
  <p>Any pointers to clear up this question?</p>
  
  <pre><code>#!/usr/bin/python
  
  import pyes
  conn = pyes.ES('sandbox:9200')
  conn.index('{"test":{"field1":"value1","field2":"value2"}}','2012.9.23','test')
  
  filter = pyes.filters.BoolFilter()
  filter.add_must(pyes.filters.LimitFilter(1))
  filter.add_must(pyes.filters.ExistsFilter('test')) #uncommenting this line returns the documents
  
  query = pyes.query.BoolQuery()
  query.add_must(pyes.query.TextQuery('test.field1','value1'))
  query.add_must(pyes.query.TextQuery('test.field2','value2'))
  
  search = pyes.query.FilteredQuery(query, filter)
  
  for reference in conn.search(query=search,indices=['2012.9.23']):
      print reference
  </code></pre>