Error: The “path” argument must be of type string. Received undefined. firebase deploy --only functions

Question

I am trying to deploy my firebase cloud functions. When I run firebase deploy --only functions after adding my functions to the index.js file it gives me the error mentioned above.

here is my firebase.json file:

  "functions": {
    "predeploy": [
      "npm --prefix \"$RESOURCE_DIR\" run lint"
    ],
    "source": "functions"
  },
  "database": {
    "rules": "database.rules.json"
  },
  "firestore": {
    "rules": "firestore.rules",
    "indexes": "firestore.indexes.json"
  }
}

here is my index.js file:

const functions = require('firebase-functions');
const algoliasearch = require('algoliasearch');
//  get api keys for the algolia from the env variable of cloud functions
const APP_ID = functions.config().algolia.app;
const ADMIN_KEY = functions.config().algolia.key;

//  algolia client
const client = algoliasearch(APP_ID, ADMIN_KEY);
const index = client.initIndex('pals');

//  ADD algolia index from firestore database when a document is created in firestore:
exports.addToIndex = functions.firestore.document('users/{userId}').onCreate(snapshot=>{
  const data = snapshot.data();
  const objectID = snapshot.id;
  //  add objectID to algolia index
  return index.addObject({...data, objectID});
});

//  UPDATE algolia index from firestore database when a document is updated in firestore
exports.updateIndex = functions.firestore.document().onUpdate(change =>{
  //  change.after gives the document after the change
  const newData = change.after.data();
  const objectID = change.id;
  //  update objectID to algolia index
  return index.saveObject({...newData, objectID});
});

//  DELETE algolia index from firestore database when a document is deleted in firestore
exports.updateIndex = functions.firestore.document().onDelete(snapshot =>{
  //  delete objectID to algolia index
  return index.deleteObject(snapshot.id);
});

I tried running firebase deploy --only functions with the hello world snippet they provide. It worked fine with that.

Answer 1

As the error message says, you need to always pass a path to the functions.firestore.document(...) function, to determine on which document paths the function triggers.

You do this correctly here:

exports.addToIndex = functions.firestore.document('users/{userId}').onCreate(snapshot=>{
  ...

But you are not passing a path in these two cases:

exports.updateIndex = functions.firestore.document().onUpdate(change =>{
  ...

exports.updateIndex = functions.firestore.document().onDelete(snapshot =>{
  ...

If you also want them to trigger on user documents, just like with onCreate , they'd be:

exports.updateIndex = functions.firestore.document('users/{userId}').onUpdate(change =>{
  ...

exports.updateIndex = functions.firestore.document('users/{userId}').onDelete(snapshot =>{
  ...