Firestore 如何从 collections 中提取子集合

Question

I have a data structure of like this.

Now i want to extract from product collection. i am already able to get its fields but don't known how to extract sub collections. Here is my code to extract product collection's field

 useEffect(() => { async function fetchData() { const conditional_fetch = query( collection(db, "products"), where("active", "==", true) ); const querySnapshot = await getDocs(conditional_fetch); const products = []; querySnapshot.forEach((doc) => { products[doc.id] = doc.data(); }); setProducts(products); } fetchData();

Answer 1

You would have to make separate requests for each products prices sub-collection. So you could try something like this:

async function fetchData() {
  // 1. Fetching products
  const conditional_fetch = query(
    collection(db, "products"),
    where("active", "==", true)
  );

  const querySnapshot = await getDocs(conditional_fetch);
  const products = [];

  // 2. For each product, fetching documents from prices sub-collection
  for (const doc of querySnapshot.docs) {
    const prices = await getDocs(
      collection(doc.ref, "prices", "timestamp", "desc")
    );
    products.push({
      id: doc.id,
      ...doc.data(),
      prices: prices.docs.map(p => p.data())
    });
  }
  setProducts(products);
}