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Efrain Mejias C
Asked: 2020-11-22 16:08:12 +0800 CST 2020-11-22 16:08:12 +0800 CST

How to get record values ​​from firebase database?

  • 772

I develop a web application and it needed to use push notifications, within the application and I am using Firebase for it… I can already use several of the functionalities.

Now you needed to retrieve records from the db.

This is how it sent the payload of the message 

function SendNotify() {
    const txt = document.getElementById('msj');
    var notificationMessage = txt.value;

    if (!notificationMessage) return false;

    database.ref('/notifications')
        .push({
            user: auth.currentUser.displayName,
            message: notificationMessage,
            userProfileImg: auth.currentUser.photoURL,
            date: date
        })
        .then(() => {
            document.getElementById('msj').value = '';
        })
        .catch(() => {
            console.log("error enviando");
        });

    txt.value = '';   
}

and in the FireBase DB it looks like this:

enter image description here

I'm trying to try to take data from here and concatenate it to another message

I wrote this and it works but the DB fields arrive as undefined:

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

exports.Notifications = functions.database.ref('/notifications/{notificationId}')
    .onWrite(async (change, context) => {
        const user = context.params.user;
        const message = context.params.message;
        const userProfileImg = context.params.userProfileImg;
        const date = context.params.date;

        // Notification details.
        const payload = {
            notification: {
                title: `Test SocialWifi de: ${user}`,
                body: `Hoy: ${date} , Nuevo Mensaje  ${message}`,
                icons: `${userProfileImg}`,
                click_action: 'https://sudokudetodos.com'
            }
        };

        console.info(payload);

    });

enter image description here

javascript

2 Answers

  1. Best Answer

    You should change your function trigger to onCreatesince you are waiting for a notification to be created, if you use onWrite()every time the document is written your function will jump, so the notification will be sent several times.

    If you are going to use async in the function, you should use await to fetch each value of the object being created before sending the notification, so you make sure that each value is captured before building the payload.

    To get the data, snap returns the entire object with the values, we use snap.data()to get the value followed by the name of the attribute we want to get

    exports.Notifications = functions.database.ref('/notifications/{notificationId}')
    .onCreate(async (snap, context) => {
        const user = await snap.data().user;
        const message = await snap.data().message;
        const userProfileImg = await snap.data().userProfileImg;
        const date = await snap.data().date;

        // Notification details.
        const payload = {
            notification: {
                title: `Test SocialWifi de: ${user}`,
                body: `Hoy: ${date} , Nuevo Mensaje  ${message}`,
                icons: `${userProfileImg}`,
                click_action: 'https://sudokudetodos.com'
            }
        };

        console.info(payload);

    });

    If it doesn't work snap.data()you can trysnap.val()

    • 2

  2. The code that worked for me as recommended by Gaston Saillen is the following:

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


    exports.Notifications = functions.database.ref('/notifications/{notificationId}')
        .onCreate(async (snap, context) => {
            const user = await snap.val().user;
            const message = await snap.val().message;
            const userProfileImg = await snap.val().userProfileImg;
            const date = await snap.val().date;

            // Notification details.
            const payload = {
                notification: {
                    title: `Test SocialWifi de: ${user}`,
                    body: `Hoy: ${date} , Nuevo Mensaje  ${message}`,
                    icons: `${userProfileImg}`,
                    click_action: 'https://sudokudetodos.com'
                }
            };

            console.info(payload);

        });

    enter image description here

    • 1