Get document from collection using specific field in firestore

Question

I am looking to get a document by using the formId field in firebase with Node.js . The formId is in a map so I'm not sure how to use the get() function for it. Here is my React code which hasn't worked. I believe it doesnt work because the formId field is contained in the formMetaData map.

    useEffect(() => {
        const firestoreRef = firebase.firestore().collection('Forms');
        // Create a query against the collection where we can match the formId
        const queryRef = firestoreRef.where('formId', '==', ID_HERE);

      }, []);

Also here is the set up of the DB:

Thank you!

Answer 1

Use the dot notation to access nested fields:

useEffect(() => {
  const firestoreRef = firebase.firestore().collection('Forms');
  // Create a query against the collection where we can match the formId
  const queryRef = firestoreRef.where('formMetaData.FormId', '==', ID_HERE); 
                                                  ^^^
  queryRef.get().then((querySnapshot) => {
    // total matched documents
    const matchedDocs = querySnapshot.size
    if (matchedDocs) {
      querySnapshot.docs.forEach(doc => {
        console.log(doc.id, "=>", doc.data())
      })
    } else {
      console.log("0 documents matched the query")
    }
  })
}, []);

queryRef is a Query and has get() method which returns a Promise containing QuerySnapshot .

The docs property on QuerySnapshot is an array of QueryDocumentSnapshot and you can use data() method on each DocumentSnapshot to access it's data.

Answer 2

You can access the formId via the formMetaData object by updating your code as follows:

useEffect(() => {
    const firestoreRef = firebase.firestore().collection('Forms');
    // Create a query against the collection where we can match the formId
    const queryRef = firestoreRef.where('formMetaData.formId', '==', ID_HERE);

  }, []);