从Cloud Functions for Firebase读取数据？

Question

I am using this code:

exports.lotteryTickets = functions.database.ref('/lottery/ticketsneedstobeprocessed/{randomID}').onWrite(event => {
    let ticketsBoughtByUser = event.data.val();

})

But ticketsBoughtByUser is not correct. How can I retrieve the the number shown in the picture below, so next to the string (oeb...)? Thank you.

I get this log:

Answer 1

In your case, event.data.val() obviously doesn't return a number. It returns an object, which you are seeing in the log. You can actually see the data in the object if you console.log(ticketsBoughtByUser) (don't use string concatenation to build the message).

For the data you show in the database, I would expect the val to be an object that contains this data (redacted so I won't have to type it):

{
    "oeb...IE2": 1
}

If you want to get the 1 out of that object, you'd have to reach into it using the string key, whatever that string represents:

const num = ticketsBoughtByUser["oeb...IE2"]

If you want just the number and not the object at the location you originally gave, you will need two wildcards to get at it directly:

exports.lotteryTickets = functions.database
        .ref('/lottery/ticketsneedstobeprocessed/{randomID}/{whatIsThis}')
        .onWrite(event => {
    const num = event.data.val()
}

I added a wildcard for whatIsThis , which will match that string I redacted above.

But I don't really know what your function is trying to accomplish, so it's just speculation as to whether or not you should actually do that.

Answer 2

You can also get the ticketsBoughtByUser value like below

const functions = require('firebase-functions');
const admin = require('firebase-admin');
admin.initializeApp(functions.config().firebase);

exports.sendNotification = functions.database.ref('/articles/{articleId}')
        .onWrite(event => {

        // Grab the current value of what was written to the Realtime Database.
        var eventSnapshot = event.data;

       //Here You can get value through key
        var str = eventSnapshot.child("author").val();

        console.log(str);

        });