title: Firebase Cloud Firestore query not finding my document
body: <p>Here's a picture of my data:
  <a href="https://i.stack.imgur.com/ZNJQq.png" rel="noreferrer"><img src="https://i.stack.imgur.com/ZNJQq.png" alt="enter image description here"></a></p>
  
  <p>I'm trying to get that document. This works:</p>
  
  <pre><code>var docRef = db.collection('users').doc('jPDKwHyrFNXNTFI5qgOY');
  docRef.get().then(function(doc) {
    if (doc.exists) {
      console.log("Document data:", doc.data());
    } else {
      console.log("No such document!");
    }
  }).catch(function(error) {
    console.log("Error getting document:", error);
  });
  </code></pre>
  
  <p>It returns:</p>
  
  <p><a href="https://i.stack.imgur.com/3yaIR.png" rel="noreferrer"><img src="https://i.stack.imgur.com/3yaIR.png" alt="enter image description here"></a></p>
  
  <p>I.e., if I know the document's key I can get the document. </p>
  
  <p>This doesn't work:</p>
  
  <pre><code>db.collection('users').where('uid', '==', 'bcmrZDO0X5N6kB38MqhUJZ11OzA3')
  .get().then(function(querySnapshot) {
    if (querySnapshot.exists) {
      console.log(querySnapshot.data);
    } else {
      console.log("No such document!");
    }
  })
  .catch(function(error) {
    console.log("Error getting document: ", error);
  });
  </code></pre>
  
  <p>It just returns <code>No such document!</code> What's wrong with my query?</p>