title: How to add Document with Custom ID to firestore in firestore 9
body: <p>How to add a custom id to a firestore document instead of automatically generated id by firebase 9?</p>
  <p>i've problem transforming this code into firebase 9 version -</p>
  <pre><code>db.collection(&quot;cities&quot;).doc(&quot;LA&quot;).set({
  name: &quot;Los Angeles&quot;,
  state: &quot;CA&quot;,
  country: &quot;USA&quot; })
  </code></pre>