title: firebase - pushing an object to an array angularFire2
body: <p>I have a db in wich I want to store data like this:</p>
  
  <pre><code>Books:
      0:{pushed Object}
      1:{pushed object} ...
  </code></pre>
  
  <p>As if it is an arrays so I can iterate over it and do the stuff I need to do. The problem is that I am storing data as pic related shows: 
  <a href="https://i.stack.imgur.com/Cd6sT.png" rel="nofollow noreferrer">pic related</a></p>
  
  <p>It is storing the object with the push_ID firebase assigns to an object but not with the index of an array. This is how I am pushing the object to my database:</p>
  
  <pre><code>let book_data = {
    id: bookId,
    name: bookData.name,
    author: bookData.author,
    genre: bookData.genre,
    publishDate: bookData.publishDate
  };
  this.fb.list(`my-lists/${bookList.name}/books/`).push(bookData);
  </code></pre>
  
  <p>What am I doing wrong?</p>
  
  <p>If needed, i'm coding this for an ionic project. </p>