title: MongoDB - finding entries using a nested dictionary
body: <p>I have a MongoDB that I use with python. My entries that looks as follows:</p>
  
  <pre><code>{
     a: something
     b: something
     c: {
          d: something
          e: something
          f: something
         }
  }
  </code></pre>
  
  <p>I want to query for entries that have a specific values for d and e but I don't care about the value in f.</p>
  
  <p>I tried not specifying f at all (similarly to when I don't care about the b value where I just not adding it to the query):</p>
  
  <pre><code>{
     a: a_value
     b: b_value
     c: {
          d: d_value
          e: e_value
         }
  }
  </code></pre>
  
  <p>I also tried to use:</p>
  
  <pre><code>{
     a: something
     b: something
     c: {
          d: something
          e: something
          f: { $exists : 1 }
         }
  }
  </code></pre>
  
  <p>but none of these worked (in fact, I got no results at all)</p>
  
  <p>How my query shall look like?</p>
  
  <p>thanks!</p>