document contain properties (columns) and can contain subcollections (one-to-many relation)
reference subcollection
const chaptersRef = collection(db, 'books', 'fE60goLDBwLtQLPyvDUH', 'chapters')
const chaptersRefVariant1 = collection(db, 'books/fE60goLDBwLtQLPyvDUH/chapters')
const chaptersRefVariant2 = collection(booksRef, 'fE60goLDBwLtQLPyvDUH', 'chapters')reference subcollection groups
to access all subcollections one time use collectionGroup
const expensesRef = collectionGroup(db, 'expenses')reference subdocument
const chapterRef = doc(db, 'books', 'fE60goLDBwLtQLPyvDUH', 'chapters', 'fE60goLDBwLtQLPyvDUH')
const chapterRefVariant1 = doc(db, 'books/fE60goLDBwLtQLPyvDUH/chapters/fE60goLDBwLtQLPyvDUH')
const chapterRefVariant2 = doc(booksRef, 'fE60goLDBwLtQLPyvDUH', 'chapters/fE60goLDBwLtQLPyvDUH')query is a subdocuments of collection
const expensesCol = collection(firestore, 'expenses')
const expensesQuery = query(
expensesCol,
// >, >=, <, <=, ==, !=
where('release', '>', new Date('6/10/2023')),
// in, not-in
where('city', 'in', ['sanaa', 'aden']),
// we can nest objects to 20 nest
where('product.cost', '>=', 200),
where('product.cost', '<=', 100),
// category is an array: [...]
where('category', '==', ['food', 'candy']),
// if category contain
where('category', 'array-contains', 'food'),
// if category contain any of
where('category', 'array-contains-any', ['food', 'candy']),
// for range functions, all of them depend on what orderBy
orderBy('date', 'desc')
// if use both it will get range of values
startAt(new Date('1/1/2022'))
endAt(new Date('/1/2022'))
limit(100)
)