How to Get Document ID in Firestore

1import { collection, getDocs, getFirestore } from 'firebase/firestore'
2
3const db = getFirestore()
4
5async function getAllUsers() {
6  const querySnapshot = await getDocs(collection(db, 'users'))
7
8  querySnapshot.forEach((doc) => {
9    console.log('Document ID:', doc.id)
10    console.log('Document data:', doc.data())
11  })
12
13  // Or use the docs array for mapping:
14  const users = querySnapshot.docs.map((doc) => ({
15    id: doc.id,
16    ...doc.data(),
17  }))
18
19  return users
20}

1import { doc, getDoc, getFirestore } from 'firebase/firestore'
2
3const db = getFirestore()
4
5async function getUserById(userId: string) {
6  const docRef = doc(db, 'users', userId)
7  const docSnap = await getDoc(docRef)
8
9  if (docSnap.exists()) {
10    console.log('ID:', docSnap.id)       // Same as userId
11    console.log('Data:', docSnap.data())
12    return { id: docSnap.id, ...docSnap.data() }
13  } else {
14    console.log('Document not found')
15    return null
16  }
17}

1import { collection, addDoc, getFirestore } from 'firebase/firestore'
2
3const db = getFirestore()
4
5async function createPost(title: string, content: string) {
6  const docRef = await addDoc(collection(db, 'posts'), {
7    title,
8    content,
9    createdAt: new Date(),
10  })
11
12  console.log('New document created with ID:', docRef.id)
13  return docRef.id
14}

1import { collection, doc, setDoc, getFirestore } from 'firebase/firestore'
2
3const db = getFirestore()
4
5async function createUserWithKnownId() {
6  // Generate a reference with an auto-ID (no network call yet)
7  const newUserRef = doc(collection(db, 'users'))
8  const userId = newUserRef.id
9
10  console.log('Pre-generated ID:', userId)
11
12  // Write the document, including its own ID as a field
13  await setDoc(newUserRef, {
14    id: userId,
15    name: 'Alice',
16    email: 'alice@example.com',
17    createdAt: new Date(),
18  })
19
20  return userId
21}

1import { collection, query, where, getDocs, documentId, getFirestore } from 'firebase/firestore'
2
3const db = getFirestore()
4
5async function getUsersByIds(userIds: string[]) {
6  // 'in' operator supports up to 30 values
7  const q = query(
8    collection(db, 'users'),
9    where(documentId(), 'in', userIds)
10  )
11
12  const snapshot = await getDocs(q)
13  return snapshot.docs.map((doc) => ({
14    id: doc.id,
15    ...doc.data(),
16  }))
17}