Multi tool use

Delete Firestore Collection using firebase function

I am trying to set up a firebase function that deletes all subcollections of a document when the document is deleted. Trough reading the documentation I have come to this code:

// The Cloud Functions for Firebase SDK to create Cloud Functions and setup triggers.
const functions = require('firebase-functions');



// // Create and Deploy Your First Cloud Functions
// // https://firebase.google.com/docs/functions/write-firebase-functions
//
// exports.helloWorld = functions.https.onRequest((request, response) => {
// response.send("Hello from Firebase!");
// });

exports.DeleteColletionFunction = functions.firestore
.document('exampleCollection/{exampleID}')
.onDelete((snap, context) => {
// Get an object representing the document prior to deletion
// e.g. {'name': 'Marie', 'age': 66}
const deletedValue = snap.data();
deleteCollection()


});



function deleteCollection(db, collectionPath, batchSize) {
var collectionRef = db.collection(collectionPath);
var query = collectionRef.orderBy('__name__').limit(batchSize);

return new Promise((resolve, reject) => {
deleteQueryBatch(db, query, batchSize, resolve, reject);
});
}

function deleteQueryBatch(db, query, batchSize, resolve, reject) {
query.get()
.then((snapshot) => {
// When there are no documents left, we are done
if (snapshot.size == 0) {
return 0;
}

// Delete documents in a batch
var batch = db.batch();
snapshot.docs.forEach((doc) => {
batch.delete(doc.ref);
});

return batch.commit().then(() => {
return snapshot.size;
});
}).then((numDeleted) => {
if (numDeleted === 0) {
resolve();
return;
}

// Recurse on the next process tick, to avoid
// exploding the stack.
process.nextTick(() => {
deleteQueryBatch(db, query, batchSize, resolve, reject);
});
})
.catch(reject);
}


I have never worked before with cloud functions and therefore am not sure what I should do next. I see that in order to use the delete Collection function it is necessary to pass a database, collectionPath and batchSize. What would be the right values to pass in this case?

Should I use this line of code to get the firestore database?

const database = admin.firestore();


I am also getting some errors when copying this function from the documentation:

Expected '===' and instead saw '=='

[eslint] Avoid nesting promises. (promise/no-nesting)
(parameter) snapshot: any

[eslint] Each then() should return a value or throw (promise/always-return)
(parameter) resolve: any

Here is a screenshot to see the locations of the errors:

Thank you for your help!

UPDATE:
I changed some things (adding a promise):

// The Cloud Functions for Firebase SDK to create Cloud Functions and setup triggers.
const functions = require('firebase-functions');

const admin = require('firebase-admin');
admin.initializeApp(functions.config().firebase);


// // Create and Deploy Your First Cloud Functions
// // https://firebase.google.com/docs/functions/write-firebase-functions
//
// exports.helloWorld = functions.https.onRequest((request, response) => {
// response.send("Hello from Firebase!");
// });

exports.DeleteColletionFunction = functions.firestore
.document('exampleCollection/{exampleID}')
.onDelete((snap, context) => {
// Get an object representing the document prior to deletion
// e.g. {'name': 'Marie', 'age': 66}
const deletedValue = snap.data();
const exampleID = context.params.exampleID;

const BATCH_SIZE = 500;

const database = admin.firestore();

const commentsRef = database.collection('exampleCollection').doc(exampleID).collection("comments");

commentsRef.doc('main').delete();

const exampleRef = database.collection('exampleCollection').doc(exampleID).collection("exampleSubCollection");
const deleteExamples = deleteCollection(database, exampleRef, BATCH_SIZE)
return Promise.all([deleteExamples]);

});



/**
* Delete a collection, in batches of batchSize. Note that this does
* not recursively delete subcollections of documents in the collection
*/
function deleteCollection (db, collectionRef, batchSize) {
var query = collectionRef.orderBy('__name__').limit(batchSize)

return new Promise(function (resolve, reject) {
deleteQueryBatch(db, query, batchSize, resolve, reject)
})
}

function deleteQueryBatch (db, query, batchSize, resolve, reject) {
query.get()
.then((snapshot) => {
// When there are no documents left, we are done
if (snapshot.size === 0) {
return 0
}

// Delete documents in a batch
var batch = db.batch()
snapshot.docs.forEach(function (doc) {
batch.delete(doc.ref)
})

return batch.commit().then(function () {
return snapshot.size
})
}).then(function (numDeleted) {
if (numDeleted <= batchSize) {
resolve()
return
}
else {
// Recurse on the next process tick, to avoid
// exploding the stack.
return process.nextTick(function () {
deleteQueryBatch(db, query, batchSize, resolve, reject)
})
}
})
.catch(reject)
}


Now I am getting errors in the firebase console:

ReferenceError: exampleID is not defined
at exports.DeleteColletionFunction.functions.firestore.document.onDelete (/user_code/index.js:26:66)
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:728:24
at process._tickDomainCallback (internal/process/next_tick.js:135:7)

Thanks for your help!

const exampleID = context.params.exampleID;

1 Answer
1

Use instead admin.initializeApp();

admin.initializeApp();

context.params.exampleID

function execution took 79 ms, finished with status: 'error'

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