Firebase cloud function returns null in Flutter because it's still running

Question

UPDATE: I'm getting this out my firebase console: Function execution took 2906 ms, finished with status code: 200 And 15 seconds later, I get: the console.log DOC DOES EXIST

I'm running this cloud firestore function. It 'works' but I got constantly this as a return: FLUTTER: NULL

But within the firebase console I get the console.log that says 'DOC DOES EXIST'.

What could be the solution to this? Language TYPESCRIPT

Thank you very much!

  export const pubVer = functions.https.onCall((data, context) => {

      console.log(data.message);

      const kRef = admin.firestore().collection('Keys').doc(data.message)
      kRef.get()
        .then(doc => {
          if (!doc.exists) {
            console.log('No such document!');
            return {returnMessage: 'FALSE'}
          } else {
            console.log('DOC DOES EXIST');
            return {'returnMessage: 'TRUE'}
          }
        })
        .catch(err => {
          console.log('Error getting document', err);
        });
      });

Solution 1

Callable functions must return a promise that resolves with the data to send to the client. As shown, the function isn't returning anything at the top level. Returning from the then callback isn't sufficient. You will also need to return the promise returned by then:

export const pubVer = functions.https.onCall((data, context) => {

    console.log(data.message);

    const kRef = admin.firestore().collection('Keys').doc(data.message)
    return kRef.get()
        .then(doc => {
          if (!doc.exists) {
            console.log('No such document!');
            return {returnMessage: 'FALSE'}
          } else {
            console.log('DOC DOES EXIST');
            return {'returnMessage: 'TRUE'}
          }
        })
        .catch(err => {
          console.log('Error getting document', err);
        });
});

Solution 2

I recommend using async/await that could help you debug

export const pubVer = functions.https.onCall(async (data, context) => {
    const documentId = data.message;
    const kRef = admin.firestore().collection('Keys').doc(documentId);
    try {
        const doc = await kRef.get();
        if (!doc.exists)
            throw new Error('No such document!');
        return doc.data();
    } catch (e) {
        console.log(e);
        return null;
    }
});

Comments

[Karel Debedts]

Thank you! When returning doc.data(), I'm trying to set a new document in firestore with the users ID and mailadress. But when I try to implement it: it says : "Promises must be handled appropriately"

[EdHuamani]

@KarelDebedts Can you share your complete function?