How to delete a document in Firestore using cloud functions

user_10941659 0
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I want to check documents as they are created in firestore to ensure there are no swear words contained in a publicly visible field. I would like to be able to delete the post after it has been detected to contain swear words. To do this I am trying to use firebase cloud functions:

// Package used to filter profanity
const badWordsFilter = require('bad words-list');

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

// The Firebase Admin SDK to access Cloud Firestore.
const admin = require('firebase-admin');
admin.initializeApp();

export const filterBadWords =
  functions.firestore.document("posts/{userId}/userPosts/{postId}").onCreate((snapshot, context) => {
    const message = snapshot.data.val();

    // Check if post contains bad word
    if (containsSwearwords(message)) {
      //This is where I want to remove the post.
      //What do I put here to delete the document?
    }
  })

// Returns true if the string contains swearwords.
function containsSwearwords(message: any) {
  return message !== badWordsFilter.clean(message);
}

Database structure:

-posts(Collection)
   |
   +---{userID} (Document)
          |
          +---userPosts (collection)
                  |
                  +---{Documents to be checked} (Document)
                  |
                  +-Url1(field)
                  +-Url2(field)
                  +-string1(field)<- check this field for swear
                  +-string2(field)<- check this field for swear

The cloud functions are written using javascript

google-cloud-firestore firebase typescript swift javascript
2 Answers

You can just use the ref to get the DocumentReference and call delete():

functions.firestore.document("posts/{userId}/userPosts/{postId}").onCreate(
  async (snapshot, context) => {
    const message = snapshot.data.val();

    // Check if post contains bad word
    if (containsSwearwords(message)) {
      await snapshot.ref.delete();
    }
  }
)

If they can edit their post afterwards, you should generalize this functionality and add it to the onUpdate trigger as well

user_31069200

This answer is going to be short, but it doesn't require an explanation. Here's the code (for swift, I'm not 100% sure how to do this in js)

swift:

db.collection("cities").document("DC").delete() { err in
    if let err = err {
        print("Error removing document: \(err)")
    } else {
        print("Document successfully removed!")
    }
}

this might work for javascript, not 100% sure

db.collection("cities").doc("DC").delete().then(function() {
    console.log("Document successfully deleted!");
}).catch(function(error) {
    console.error("Error removing document: ", error);
});

hope it helps

user_144653810
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