How to get data in Firebase Firestore from the Reference data type in React Native

Question

Hello I have a collection called Meal. In this collection i used the data type reference to link another collection called Ingredient. Now I'm trying to get the ingredients to the specific meal.

This is my code:

 function Meal() { const [loading, setLoading] = useState(true); // Set loading to true on component mount const [meal, setMeal] = useState([]); // Initial empty array of meal useEffect(() => { const subscriber = firestore().collection('Meal').onSnapshot((querySnapshot) => { const meal = []; querySnapshot.forEach(documentSnapshot => { meal.push({...documentSnapshot.data(), key: documentSnapshot.id, }); }); setMeal(meal); setLoading(false); }); // Unsubscribe from events when no longer in use return () => subscriber(); }, []); if (loading) { return <ActivityIndicator />; } return ( <List style={styles.container} contentContainerStyle={styles.contentContainer} data={meal} renderItem={({ item }) => ( <Card style={styles.item}> <Text style={styles.title}> {item.Name} </Text> <Layout> <Image style={{ height: 128, borderRadius: 5, borderWidth: 2, borderColor: 'black', marginHorizontal: -20 }} source={{ uri: item.srcImage}} /> </Layout> <Text> {item.Ingredient[0].id} </Text> </Card> )} /> ); }

The keywords item.Ingredient[0].id and ìtem.Ingredient[0].path are working properly but I can't get the information stored in the collection Ingredient. Do I need another querySnapshot?

Answer 1

Do I need another querySnapshot?

If you want to read a document in a second collection, it will require a second query. There are no "join" type operations in Firestore, and queries will not follow references automatically.