Delete an array element using Firebase 9

Question

I've a simple document in my Firestore collection.

{
  "posts": ["0", "1", "3"],
  "title": "Delete an array element"
}

I know how to delete an entire document using the auto generated Direbase doc id but I'm not sure how do I delete a specific element in an array, let's here I'd like to delete the 1.
And I don't want to use updateDoc for this to work.
Using Javascript for the integration.

What is the programming language you're using? Please also edit your question and add your database structure as a screenshot. — Alex Mamo
– Alex Mamo, Commented Jun 22, 2022 at 15:01
@AlexMamo I've added the firestore structure and I am using Javascript — Chandler Bing
– Chandler Bing, Commented Jun 22, 2022 at 17:41

Dharmaraj · Accepted Answer · 2022-06-22 17:41:06Z

2

The updateDoc() function is required to update a document. You can use arrayRemove() function to remove an element from the array.

import { doc, updateDoc, arrayUnion, arrayRemove } from "firebase/firestore";

const docRef = doc(db, "collection", "docId");

await updateDoc(docRef, {
    posts: arrayRemove("1") // removes "1" from the array 
});

Do note that if you have an array of objects then you must pass the entire object to be removed in arrayRemove().

answered Jun 22, 2022 at 17:41

Dharmaraj

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2 Comments

Chandler Bing Over a year ago

Exactly what I needed, Though I have one question, How can I delete an object. Cause I see you've used an arrayRemove function and basically we have pass the exact element for to remove that element. Thanks.

Dharmaraj Over a year ago

@random_18 in case of array of objects you need to know the exact object. If you only know value of a single property then you cannot use arrayRemove(). You will then have to read the document first and update manually as explained here

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