I am trying to copy data from one collection to another collection not sure what I am doing wrong or right I am trying to copy everything that is in "todo" with date equal to 2021-08-14 and copy it to "template" so far all I can to do is get the data from todo and print to console
const db = firebase.firestore();
const todoRefFrom = db.collection('todo');
const todoRefTo = db.collection('templates');
const todos = await todoRefFrom.get();
todos.forEach(async doc => {
console.log('set set', doc);
todoRefTo.set(Map.fromEntries(doc.data().entries));
});
Just query todo collection for documents having startDate as 14 August. Then just save all the documents to your new collection, in batches which is performance-wise better way.
const db = firebase.firestore();
const todoRefFrom = db.collection('todo');
const todoRefTo = db.collection('templates');
let startDate = new Date('2021-08-14');
let endDate = new Date('2021-08-15');
const todos = await todoRefFrom.where('dateField', '>=', startDate).where('dateField', '<', endDate).get();
let writeBatch = firebaseAdmin.firestore().batch();
let i = 0;
for (let doc of todos.docs) {
writeBatch.set(todoRefTo.doc(doc.id), doc.data());
i++;
if (i > 400) { // write batch only allows maximum 500 writes per batch
i = 0;
console.log('Intermediate committing of batch operation');
await writeBatch.commit();
writeBatch = firebaseAdmin.firestore().batch();
}
if (i > 0) {
console.log('Firebase batch operation completed. Doing final committing of batch operation.');
await writeBatch.commit();
} else {
console.log('Firebase batch operation completed.');
}
});
Inspired from @Lahiru Chandima's answer here, https://stackoverflow.com/a/60137639/3857918
PS: I have replaced your forEach with simple for..of loop here. The forEach async calls don't run in a sequence, can cause a lot of problems sometimes during debugging.