title: how to set server time stamp with firestore admin nodejs sdk?
body: <pre><code>const firebase = require('@firebase/app').default;
  require('@firebase/firestore')
  
  const admin = require('firebase-admin')
  const functions = require('firebase-functions')
  
  // initialize the admin SDK...    
  
  exports.setUpdatedDate = functions.firestore.document('/foos/{fooId}/bars/{barId}')
      .onCreate(event =&gt; {
        admin.firestore().collection('foos').doc( event.params.fooId )
              .set({
                  updatedDate: firebase.firestore.FieldValue.serverTimestamp()
              }, {merge:true})
      })
  </code></pre>
  
  <p>Running the function shell above and I got:</p>
  
  <pre><code>Cannot encode type ([object Object]) to a Firestore Value
  at Function.encodeValue (...\functions\node_modules\@google-cloud\firestore\src\document.js:772:11
  </code></pre>
  
  <p>so how to set server time stamp with firestore admin nodejs sdk?</p>