I am trying to retrieve an object the i added to my firebase realtime database But i am not getting anything and i dont know why . i made sure to implement and call firebase correctly .
This is the response i get one i cal the database .
and this is my imlimentation
<script>
var firebaseConfig = {
apiKey: "*",
authDomain: "*",
databaseURL: "*",
projectId: "*",
storageBucket: "*",
messagingSenderId: "*",
appId: "*"
};
// Initialize Firebase
firebase.initializeApp(firebaseConfig);
var dbRef = firebase.database();
var contactsRef = dbRef.ref("survey");
console.log(contactsRef)
</script>
You need to attach a listener to retrieve the data:
var dbRef = firebase.database();
var contactsRef = dbRef.ref("survey");
contactsRef.once('value').then(function(snapshot) {
console.log(snapshot.val());
});
snapshot.val() will give you all the data under node survey.
For more information check this:
https://firebase.google.com/docs/database/web/read-and-write#read_data_once
Related
I'm trying to delete some data from firebase realtime database after some time but gives me this error: Uncaught TypeError: ref2.orderByChild is not a function
this is the code:
import { initializeApp } from "https://www.gstatic.com/firebasejs/9.8.1/firebase-app.js";
import {getDatabase, ref, child, onValue, get} from "https://www.gstatic.com/firebasejs/9.8.1/firebase-database.js"
import "https://cdn.jsdelivr.net/npm/seamless-scroll-polyfill#latest/lib/bundle.min.js";
const firebaseConfig = {
apiKey: "xxxxx",
authDomain: "xxxxx",
databaseURL: "xxxxx",
projectId: "xxxxx",
storageBucket: "xxxxx",
messagingSenderId: "xxxxx",
appId: "xxxxx"
};
const app = initializeApp(firebaseConfig);
const db = getDatabase();
var ref2 = ref(db, "/2021-2022/Pentamestre/Voti/Novità");
var now = Date.now();
var cutoff = now - 2 * 60 * 60 * 1000;
var old = ref2.orderByChild('timestamp').endAt(cutoff).limitToLast(1);
var listener = old.on('child_added', function(snapshot) {
snapshot.ref.remove();
});
Obviously in firebaseConfig the datas are presents, i only hidden them here
There's a top level function query() in the new Modular SDK to build a Query. Similarly, orderByChild() and other query constraints are also a function. Try refactoring the code as shown below:
var old = query(ref2, orderByChild('timestamp'), endAt(cutoff), limitToLast(1));
var listener = onChildAdded(old, function(snapshot) {
// ...
});
I see you imported "get" but didnt use it,
and the ref "/2021-2022/Pentamestre/Voti/Novità" is maybe
"2021-2022/Pentamestre/Voti/Novità"
as path doesnt start with /slash
currently I creating the website using cloud firestore as my database. Right now I can query the data from my collection but it didn't work when I try to display that data on my html web page.
const firebase = require("firebase/app")
require("firebase/firestore")
var firebaseConfig = {
apiKey: "AIzaSyCxrJbfDOorE9H4E0I2O98tLftoxFAHNLU",
authDomain: "school-bus-tracking-syst-3ff71.firebaseapp.com",
databaseURL: "https://school-bus-tracking-syst-3ff71.firebaseio.com",
projectId: "school-bus-tracking-syst-3ff71",
storageBucket: "school-bus-tracking-syst-3ff71.appspot.com",
messagingSenderId: "200434933461",
appId: "1:200434933461:web:4cece32389af487c944c5c",
measurementId: "G-Q9C278TWTV"
};
firebase.initializeApp(firebaseConfig);
var firestore = firebase.firestore();
const inputTextfield = document.querySelector("#contactnum");
const docRef = firestore.doc("driver/D001");
docRef.get()
.then(function(querySnapshot) {
querySnapshot.forEach(function(doc) {
inputTextfield.innerText = doc.data().contactNo;
});
})
.catch(function(error) {
console.log("Error getting documents: ", error);
});
and my HTML file is
<script src="https://www.gstatic.com/firebasejs/7.13.2/firebase-app.js"></script>
<script src="https://www.gstatic.com/firebasejs/7.13.2/firebase-firestore.js"></script>
<input type="text" id="contactnum">
<script scr = "./we.js"></script>
I tried this but I don't get anything display on my html website. Thank you in advance!
Using html/JS, I am trying to write a file.
I included this on html head :
<head>
<script src="https://www.gstatic.com/firebasejs/5.7.0/firebase-app.js"></script>
<script src="https://www.gstatic.com/firebasejs/5.7.0/firebase-firestore.js"></script>
Then at the end of the body I have :
//...
<script src="javascripts/main.js"></script>
<script>
var config = {
apiKey: "xxx",
authDomain: "xxxx.firebaseapp.com",
databaseURL: "https://xxxx.firebaseio.com",
projectId: "xxxx",
storageBucket: "xxxx.appspot.com",
messagingSenderId: "xxxxx"
};
firebase.initializeApp(config);
const db = firebase.firestore();
db.settings({timestampsInSnapshots:true});
</script>
Then on the main.js file when I try to write to storgae :
var storageRef = firebase.storage().storage.ref()('me/' + file.name);
var task=storageRef.put(file);
task.on('state_changed',
function progress(snapshot){console.log(snapshot.bytesTransferred)},
function error(err){},
function complete(){});
I get this error on the console :
firebase.storage is not a function
EDIT:
Tried again and got same error with :
// Create a root reference
var storageRef = firebase.storage().ref();
// Create a reference to 'images/mountains.jpg'
var finalRef = storageRef.child('me/' + file.name);
finalRef.put(file).then(function(snapshot){
console.log('uploading');
});
you need to add this also:
<script src="https://www.gstatic.com/firebasejs/5.7.0/firebase-storage.js"></script>
to be able to use firebase storage api.
Also change this:
var storageRef = firebase.storage().storage.ref()('me/' + file.name);
Into this:
var storageRef = firebase.storage().ref('me/' + file.name);
Check this for more info:
https://firebase.google.com/docs/storage/web/create-reference
change you script main.js position like this
<script>
var config = {
apiKey: "xxx",
authDomain: "xxxx.firebaseapp.com",
databaseURL: "https://xxxx.firebaseio.com",
projectId: "xxxx",
storageBucket: "xxxx.appspot.com",
messagingSenderId: "xxxxx"
};
firebase.initializeApp(config);
const db = firebase.firestore();
db.settings({timestampsInSnapshots:true});
</script>
//to here
<script src="javascripts/main.js"></script>
Check whether your firebase import is correct. It won't work if you imported it incorrectly.
It should be like this
import * as firebase from "firebase/app";
Not this
import * as firebase from "firebase";
// Initialize Firebase
var config = {
apiKey: "AIzaSyBz13eirmEOGD1uXOZwf6tKGnEsjfwsUFo",
authDomain: "platformtechproject.firebaseapp.com",
databaseURL: "https://platformtechproject.firebaseio.com",
projectId: "platformtechproject",
storageBucket: "platformtechproject.appspot.com",
messagingSenderId: "1065758005439"
};
firebase.initializeApp(config);
var database = firebase.database();
ref msgs clllection
var msgRef = firebase.database().ref('survey');
I am trying to connect to firebase, but I continue getting these errors on chrome console failing to connect to firebase:
Chrome console error
This is because you did not write:
<script src="https://www.gstatic.com/firebasejs/4.12.0/firebase.js"></script>
in the <head>...</head>
You have to write it to be able to use the firebase sdk in your project.
more info here:
https://firebase.google.com/docs/web/setup
I want to set up a Firebase Real-time Database connection from my Java backend to my JavaScript frontend, but the messages are not pushed to the client.
The backend Java code looks like this:
FirebaseOptions options = new FirebaseOptions.Builder()
.setServiceAccount(getServletContext().getResourceAsStream("/WEB-INF/xxx.json"))
.setDatabaseUrl("https://xxx.firebaseio.com")
.build();
FirebaseApp.initializeApp(options);
DatabaseReference ref = FirebaseDatabase
.getInstance()
.getReference();
ref.child("users").setValue("aaa");
My javascript code on the frontend looks like this:
var config = {
apiKey: "xxx",
authDomain: "xxx.firebaseapp.com",
databaseURL: "https://xxx.firebaseio.com",
storageBucket: "xxx",
messagingSenderId: "xxx"
};
firebase.initializeApp(config);
var database = firebase.database();
var myRef = firebase.database().ref("users");
myRef.on('value', function(snapshot) {
alert(5);
});
Is there something wrong with this code or why are the messages are not pushed? Am I missing something?