JavaScript get data from Firebase fail - javascript

This is my own firebase structure.
I want to get the particular data in firebase, for example: win. I get an error message for it. I have no idea to handle those particular id that create with firebase.
This my JavaScript code. When I run the program,the browser told me that the problem is in line 17.

You can listen for changes on child nodes, or you can fetch a node on demand. See documentation.
Listen for value events
var starCountRef = firebase.database().ref('posts/' + postId + '/starCount');
starCountRef.on('value', function(snapshot) {
updateStarCount(postElement, snapshot.val());
});
or read data on demand
var userId = firebase.auth().currentUser.uid;
return firebase.database().ref('/users/' + userId).once('value').then(function(snapshot) {
var username = (snapshot.val() && snapshot.val().username) || 'Anonymous';
// ...
});

Related

How to get Data from Firebase-Database in Real-Time with Javascript

Hello I would like to automatically generate an alert in realtime as soon as a value in my Firebase database has changed. My code looks like this:
try {
var ref = firebase.database().ref("URL").child("1");
ref.on("child_changed", function(snapshot) {
var changedPost = snapshot.val();
alert(changedPost);
});
}
catch(err) {
alert("Error");
}
As you can see the structure of my database is:
Could someone tell me what is wrong with this code and why I don't get an alert when something changes in my database?
I would appreciate an answer.
You're listening for child_changed events, which fires when a property under /URL/1 changes. To instead get called when the value in /URL/1 changes, listen for a value event:
ref.on("value", function(snapshot) {
var changedPost = snapshot.val();
alert(changedPost);
});

How can i get data from firebase

I want to do a user search vie search bar.when I enter the last name I should receive data about users if there are matches but i don't know how.
here is my try
searchBar(){
let a=app.database().ref('users/'+app.auth().currentUser.uid).orderByChild('/surname').equalTo('Крюкин');
console.log(a);
}
here is structure of data
Try the following:
searchBar(){
let a=app.database().ref('users');
a.orderByChild('surname').equalTo('Крюкин').on('value',((snapshot) => {
snapshot.forEach((childSnapshot) => {
console.log(childSnapshot.val());
});
}
First you are not using a userID, that's a random id generated using push() in your database. Therefore you need to use forEach() to access the data.
Check the guide:
https://firebase.google.com/docs/database/web/read-and-write
you dont exactly read data from firebase.
You should create a handle, which you did, a in your case
and then on that handle you register value event listener the code below is from official docs
ref.once('value', function(snapshot) {
snapshot.forEach(function(childSnapshot) {
var childKey = childSnapshot.key;
var childData = childSnapshot.val();
// ...
});
});
in your case you shloud just to
a.on("value",list=>{list.forEach(...)})
also you can subscribe for future child_added/removed/updated events
here are the docs

Dialogflow Firebase Realtime Database Getting Error: No responses defined for platform: Undefined yet method still goes through

I've been trying for a project I'm working on to develop a function for a Food chatbot. What I'm currently working on is to perform a method for a user to make a purchase of an order that is stored in firebase realtime database.
The method is set as the method for an actionMap and the actionMap is linked to an intent for knowing when to call the method and for retrieving the parameters.
My current method uses a simple check for a user's existence and status within the database before identifying the existence of the order they're trying to make a purchase for by its id by going through the user's reference path and doing a .forEach to check every order found and look at its parent folder name to check if it matches the user's order id. My code is as follows:
const MakePurchaseACTION = 'Make Purchase';
function makePurchase(app){
let email = parameter.email;
let orderId = parameter.orderId;
var currDate = currDateGenerator();
var name = email.split(".com");
//Check if User exists first in database
var userRef = database.ref().child('user/' + name);
return userRef.once('value').then(function(snapshot) {
if (snapshot.exists()) {
let statusRetrieved = snapshot.child('Status').val();
//Check if user's status in database is signed in.
if (statusRetrieved == "Signed In") {
var orderRef = database.ref().child('order/' + name);
//Check the order table for the user.
return orderRef.once('value').then(function(orderSnapshot){
let orderVal = orderSnapshot.val();
console.log(orderVal);
//Check through every child for the matching id.
orderSnapshot.forEach(function(childSnapshot) {
let orderIdFound = childSnapshot.key;
//let cost = childSnapshot.child('Cost').val();
console.log(orderIdFound);
if(orderId == orderIdFound) {
let eateryName = childSnapshot.child('Eatery').val();
let eateryLocation = childSnapshot.child('EateryLocation').val();
let deliveryAddress = childSnapshot.child('DeliveryAddress').val();
let orderItem = childSnapshot.child('OrderItem').val();
let quantity = childSnapshot.child('Quantity').val();
let cost = childSnapshot.child('Cost').val();
var purchaseRef = database.ref().child('purchase/' + name + "/" + currDate + "/" + orderId);
purchaseRef.set({
"Eatery" : eateryName,
"EateryLocation" : eateryLocation,
"DeliveryAddress": deliveryAddress,
"OrderItem" : orderItem,
"Quantity": quantity,
"Cost": cost,
"DateCreated": currDate
});
app.add("You have successfully purchased Order " + orderId);
} else {
app.add("There is no order with that id.");
}
});
});
} else {
app.add("You need to be signed in before you can order!");
}
}
else {
app.add("Sorry pal you don't exist in the database.");
}
});
}
actionMap.set(MakePurchaseACTION, makePurchase);
After checking through some firebase logs
Firebase Logs screenshot here
Firebase Realtime Database Order Table Sample
I found that the method actually completes Purchase table sample but my dialogflow returns with the stated error of:
Error: No responses defined for platform: undefined and displays "Not Available" back to the user. My question is how do I go about resolving this error?

Firebase how to find child knowing its id but not its parent's id (js)

I have a firebase realtime database (not cloud) structure like:
users
kasdf872ajsda //user id
auiiq6d182g1 //list id
c: <mycontent> //list content
i know the list id (in this case auiiq6d182g1) and i want to retrieve <mycontent>, but i don't know the user id kasdf872ajsda , because what i'm going to retrieve is probably not from the user currently using the website (and i'm not setting any database rules for "read" in fact, only for "write" is that correct?).
What i'm doing right now is this (not working):
var ref = firebase.database().ref().child('users');
ref.child(listID).once("value", function(snapshot) {
var snap = snapshot.val();
myContent = snap.c;
});
You could put your reference to users first: var ref = firebase.database().ref('users');
Then loop through:
ref.once('value').then((snapshot)=>{
snapshot.forEach(function(data) {
if (data.key == <YOUR_LIST_ID>) {
//you can access data.c here...
}
});
});
Found the solution, if someone should encounter the same issue:
ref.once("value", function(snapshot) {
snapshot.forEach(function(data) {
snap = data.child(<YOUR_LIST_ID>).child('c').val();
if (snap != null){
myContent = snap;
}
});
});
also ref contrary to what everyone says has to be:
var ref = firebase.database().ref().child('users');
this doesn't work:
var ref = firebase.database().ref('users');

Firebase Web retrieve data

I have the following db structure in firebase
I'm trying to grab data that belongs to a specific user id (uid). The documentation has the following example:
firebase.database().ref('/users/' + userId).once('value').then(function(snapshot) {
var username = snapshot.val().username;
// ...
});
But how can I retrieve data from my example without knowing the unique key for each object?
Update:
I tried a new approach by adding the user id as the main key and each child object has it's own unique id.
Now the challenge is how to get the value of "title".
firebase.database().ref('/tasks/').orderByChild('uid').equalTo(userUID)
Well that is pretty straightforward. Then you can use it like this:
return firebase.database().ref('/tasks/').orderByChild('uid').equalTo(userUID).once('value').then(function(snapshot) {
var username = snapshot.val().username;
// ...
});
Of course you need to set userUID.
It is query with some filtering. More on Retrieve Data - Firebase doc
Edit: Solution for new challenge is:
var ref = firebase.database().ref('/tasks/' + userUID);
//I am doing a child based listener, but you can use .once('value')...
ref.on('child_added', function(data) {
//data.key will be like -KPmraap79lz41FpWqLI
addNewTaskView(data.key, data.val().title);
});
ref.on('child_changed', function(data) {
updateTaskView(data.key, data.val().title);
});
ref.on('child_removed', function(data) {
removeTaskView(data.key, data.val().title);
});
Note that this is just an example.

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