title: Firestore : Query documents by property of objects
body: <p>To Query from <code>Firebase Firestore</code> documents by using properties of objects.</p>
  
  <p><strong><em>My Data Structure :</em></strong>  </p>
  
  <pre><code>document{  
    id:"document-id",
    user: {
      name:"John",
      email:"example@gmail.com"
    }
  }
  </code></pre>
  
  <p><em>How to query from a collection in which I want documents having "example@gmail.com" as email address of user.</em></p>
  
  <p><strong><em>Note:</em></strong><br>
  This question is similar to this one : <a href="https://stackoverflow.com/q/49613117/9636037">Firestore: Query documents by property of object</a><br>
  But, that question is for backend(node) and this one is for frontend(java).</p>