Question 219206 in Javascript Question posted in
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Javascript – Firestore get single element by searching with its fields

I have collections of restaurants.
ss1

I want to retrieve single document.However, I don’t have documentID, I only have email so I want to write a query which returns a single document when i give it an
The email field is unique there will be no duplicated document with it.

I am current using this silly query:

      const q = query(
        collection(fireStore, "restaurant"),
        where("email", "==", user?.email),
        limit(1)
      )
      const querySnapshot = await getDocs(q);
      querySnapshot.forEach((doc) => {
         setRestaurant(doc.data());
      });

The querySnapshot is an array which contains single element.

Is it possible to write a query which return single document not an array of single document?

or you can also suggest better ways to doing this like first find documentID then retrieve with documentID.

Tags:

2

Answers


  1. 0

    Since a query can match multiple documents, it will always return a QuerySnapshot and that will always contains an array of documents. Even if the query only returns a single document, it will be in the form of a QuerySnapshot and an array.

    If you know there is only a single document, or if you only care about the first document of the results, you can access that without needing a loop:

    const doc = querySnapshot.docs[0];
setRestaurant(doc.data());
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  2. 0

    As an alternative to Frank’s answer, you could also create your own getter function that returns the first result as if you were using getDoc().

    async function getFirstDoc(queryObj) {
    const querySnapshot = await getDocs(
      query(queryObj, limit(1)) // adds the limit constraint for efficiency
    );
    return querySnapshot.docs[0]
      || {
        exists: () => false,
        get: () => undefined,
        data: () => undefined
      };
}

    Then you can use it elsewhere in your code like so:

    const q = query(
  collection(fireStore, "restaurant"),
  where("email", "==", user?.email)
);

const doc = await getFirstDoc(q);
setRestaurant(doc.data()); // assuming doc always exists, otherwise check doc.exists()
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