Cloud Function 在部署时不会保存到 Firestore

Question

I have deployed a cloud function that loads an API and saves its contents to my Firestore database. It is working perfectly when I run the cloud function on my local environment using the firebase emulators. However, when I have deployed the same function to the Google Cloud Platform, it fails to save the contents to Firestore although it loads the API successfully. What else could I have been missing from my setup?

Here is the code. I purposely redacted the API link.

const functions = require('firebase-functions');
const rp = require('request-promise');
const admin = require('firebase-admin');
const axios = require('axios');

admin.initializeApp({
    credential: admin.credential.applicationDefault()
});

 exports.savePSEData = functions.https.onRequest((req, res) => {
    const url = <LINK REDACTED>;
    return new Promise((resolve, reject) => {

        axios
            .get(url)
            .then(response => {
                const date = response.data.as_of;
                for (var index in response.data.stock) {
                    var stock = response.data.stock[index]
                    createStockDocument(date, stock.symbol, stock.price.amount, stock.percent_change, stock.volume, callback => {
                        console.log(index)
                    })
                }
               return res.status(200).send("ok");
            })
            .catch(error => {
                console.log(error);
               return res.status(500).send(error);
            });
    })

});

function createStockDocument(date, symbol, amount, percentChange, volume, callback) {
    console.log("Creating temp package")
    const docRef = admin.firestore().doc(`${symbol}/${date}`);
    docRef.set({ 
        amount: amount,
        percent_change: percentChange,
        volume: volume
    })
    .then(docRef => {
        console.log('Document created')
        return callback(docRef)
    }).catch(error => {
        console.log(`Error trying to create document ${error}`)
        return callback(error);
    })

}

Answer 1

Your code is ignoring the promise returned by docRef.set().then(...).catch(...) . Calling then and catch does not fully handle the promise. catch just returns another promise that resolves asynchronously after the entire chain resolves. This means that your function is also sending the response to the client before Firestore has completed the write, which means it might never complete. Functions are terminated immediately after the response is set.

You should make createStockDocument return that promise from the chain, then make the caller of the function wait for it before sending the response. Minimally:

function createStockDocument(date, symbol, amount, percentChange, volume, callback) {
    console.log("Creating temp package")
    const docRef = admin.firestore().doc(`${symbol}/${date}`);
    return docRef.set(...).then(...)
}

I suggest not using catch here, and instead have the caller catcher any errors.

createStockDocument(...)
.then(() => res.status(200).send("ok"))
.catch(error => res.status(500).send(error))

I strongly suggest getting a firm grasp of how promises work, as they are crucial to writing effective code in Cloud Functions.