Return data from firebase function to app

问题

In my ionic app I am connecting to a stripe payment gateway.

I have a function in firebase which is being triggered on updating the customer.

exports.updateStripeCustomer = functions.database.ref("/Customers/{userId}")
  .onUpdate((snapshot, context) => {
    const data = snapshot.after.val();
    return stripe.customers.createSource(data.payment_sources.customer_id, {
        source: data.payment_sources.source
    }).then(customer => {
        console.log("Update Stripe Customer");
        return customer;
    },
        error => {
            return error;
        }
    );
});

This is my code in the app end where I am updating the customer. While updating the trigger called in firebase, how do I get the data returned by the trigger (firebase function) in my below code?

 this.angularDb.object('/Customers/' + firebase.auth().currentUser.uid).update({
            cardsetup: 1,            
            payment_sources: {
              customer_id: this.user.customer_id,
              source: this.card.source.id
            }
          }).then((res) => {
            loading.dismiss();
            alert("card details has been successfully updated.");            
            this.navCtrl.push(LoginPage);

      }, (error) => {
        loading.dismiss();
        console.log("=========>", error.message)
        alert(JSON.stringify(error))
      });

If the firebase function returns an error I need to show that error message returned by the trigger. Any way to do this?

回答1:

The trigger reacts to an event in the database and doesn't know anything about your application. Therefore there is no link between your trigger and your application.

You could add a Transaction collection to your users with a transaction id and a transaction status. Then listen to it from your application and update it from the trigger to get notified when it is complete.

Or your could use a callable cloud functions instead of a trigger. https://firebase.google.com/docs/functions/callable

来源：https://stackoverflow.com/questions/56301600/return-data-from-firebase-function-to-app