how to add sub collection to a document in firestore? [closed]
Your code should work if you change .set to .add. Cloud Firestore will then issue a new ID for that document. If you want to specify the document ID, then you'll need to do this...
Set a book with a given ID
db.collection('users').doc(this.username).collection('booksList').doc(myBookId).set({
password: this.password,
name: this.name,
rollno: this.rollno
})
This page details how to Add data to Cloud Firestore
Add a book
db.collection('users').doc(this.username).collection('booksList').add({
password: this.password,
name: this.name,
rollno: this.rollno
})