I am trying to remove an array element from an array in a document using the method updateDoc, for that I need the document reference however I do not know how to get it as it was one generated by Firebase and the documentation or past questions have not helped. This is my code:
const subjectRef = collection(db, "users", auth.currentUser.uid, "subjects");
const querySnapshot = await getDocs(subjectRef);
subjects.forEach(subject => {
querySnapshot.forEach((doc) => {
if(doc.data().Subject == subject) {
const subject = doc.data();
const subjectName = subject.Subject;
const topics = subject.Topics;
//iterates through the topics of the subjects
globalTopicList.forEach(obj => {
topics.forEach(async topic => {
if(obj[1]==topic.id) {
const temp = {
Topic: topic.Topic,
Days: 0,
Rating: topic.Rating,
id: topic.id,
};
await updateDoc(docRef, {
Topics: arrayRemove(topic.id)
});
console.log('done');
}
});
});
}
});
});
Each QueryDocumentSnapshot has a .ref property that is the DocumentReference of that document:
const updates = [];
querySnapshot.forEach((doc) => {
const docRef = doc.ref
updates.push(updateDoc(docRef, {...updatedData}))
})
return Promise.all(updates).then(() => {
console.log("Documents updated")
}).catch((e) => console.log(e))
If you are updating less than 500 documents, then you can update them at once using a Batched Write:
import { writeBatch, doc } from "firebase/firestore";
const batch = writeBatch(db);
querySnapshot.forEach((doc) => {
const docRef = doc.ref
batch.update(docRef, {...updatedData}))
})
// Commit the batch
await batch.commit();