how to add child collection in parent collection in firebase-CodePudding

So I'm having a problem that I can't think else how can I add another collection in the parent/first collection let say the diagram should something look like this

owner-item:
  group-item: [],
  single-item: []

Let say in firebase-collection.js it look something like this

import { collection } from 'firebase/firestore'
import { db } from './firebase'

export const owneritemsRef = collection(db,'owner-items')

And then now I'm exporting now the collection by something like this

let uploadUserStorageTask = uploadBytesResumable(list[i],pictures[j].data)
    ....
},(err) => {
    console.log(err)
},() => {
    getDownloadURL(uploadUserStorageTask.snapshot.ref)
    .then(async (downloadURL) => {
        await setDoc(doc(db,`owner-items`,`${currentUser?.email}-${uid}`),{
        creator:username,name:name,img:downloadURL,email:currentUser?.email
        })
        .then( res => {})
        .catch(err => {})
        })
})

but because I have group-images I want them to set in a group-item collection but I was thinknig await setDoc or something else I should added to make it like a group-item collection in the owner-item parent collection but how can I do it?

I search something related to it and it something like this maybe? LINK...but I want setDoc because I can change my document_id

UPDATE It is something like this.... LINK

import { doc } from "firebase/firestore"; 

const messageRef = doc(db, "rooms", "roomA", "messages", "message1");

I'm sorry its about document inside of collection...let say

await setDoc(..., {
   group_item: {},
   single_item: {},
}

based on my old snippet just add this new thing... Is this the righht way to do it? or something like subcollection you know what I mean.

UPDATE 2 let say I have owner-items

await setDoc(doc(db,`owner-items`,`${currentUser?.email}-${uid}`),{
    group_items:[{
        id:1,
        img:file-image
    }], 
    single_item:[{
        id:1,
        img:file-image
    }]
})

CodePudding user response：

If I understand correctly your answer and comments, the following, using a batched write, should do the trick.

import { writeBatch, doc } from "firebase/firestore";

const batch = writeBatch(db);

const parentDocRef = doc(db, `owner-items`, `${currentUser?.email}-${uid}`);
batch.set(parentDocRef, {
    single_item: [{
        id: 1,
        img: file - image
    }]
});

const group_items = [
    {
        id: 1,
        img: file - image
    },
    {...}
];

group_items.forEach(elem => {
    const groupItemDocRef = doc(db, `owner-items`, `${currentUser?.email}-${uid}`, 'group-items');
    batch.set(groupItemDocRef, {
        item: elem
    });
});

await batch.commit();

Note that a batched write can contain up to 500 operations, so your group_items array shall have maximum 499 elements.