node js function onWrite is not working properly in google cloud function

Question

I have this node js function that attempts to update Algolia index once a add/update/delete is done to node Listings

exports.indexlisting_algolia = 
    functions.database.ref('/Listings/{listingId}').onWrite((snapshot, context) => {
   const index = algolia.initIndex('Listings');
   // var firebaseObject = snapshot.data;
   var firebaseObject = snapshot.data.val();
   console.log("test ",firebaseObject)

   firebaseObject.objectID = context.params.listingId;


  return index.saveObject(firebaseObject).then(
  () => 
   snapshot.data.adminRef.parent.child('last_index_timestamp').set(
      Date.parse(event.timestamp)));
  });

this is my error thraceback

TypeError: Cannot read property 'val' of undefined at exports.indexlisting_algolia.functions.database.ref.onWrite (/user_code/index.js:807:40) at Object. (/user_code/node_modules/firebase-functions/lib/cloud-functions.js:112:27) at next (native) at /user_code/node_modules/firebase-functions/lib/cloud-functions.js:28:71 at __awaiter (/user_code/node_modules/firebase-functions/lib/cloud-functions.js:24:12) at cloudFunction (/user_code/node_modules/firebase-functions/lib/cloud-functions.js:82:36) at /var/tmp/worker/worker.js:733:24 at process._tickDomainCallback (internal/process/next_tick.js:135:7)

line 807 is this function

var firebaseObject = snapshot.data.val();

what am I doing wrongly and how can I fix this?

Doug Stevenson Doug Stevenson · Accepted Answer · 2018-09-06T23:38:18

You're using an old version of the API exposed by the firebase-functions module. The new one requires that you accept a Change object, with before and after attributes, as the first parameter of onWrite and onUpdate triggers. Those attributes will be DataSnapshot objets. Your code is currently expecting a DataDeltaSnapshot, which is what you got in the beta version before the full 1.0 release. This is now deprecated.

You can read about the API changes in version 1.0 in the documentation.

Please also see the documentation for database triggers for examples.

Your function should look more like this:

exports.indexlisting_algolia = 
    functions.database.ref('/Listings/{listingId}')
    .onWrite((change, context) => {
        const before = change.before;  // snapshot before the update
        const after = change.after;    // snapshot after the update
        const before_data = before.val();
        const afater_data = after.val();
    })

node js function onWrite is not working properly in google cloud function

1 Answers