I have the following structure on my Firebase database:
I would like to search for a user by name, last name or email but as I don't have the user key in the level above I don't know how I can achieve this. I'm doing and administrator session so it wouldn't have access to the user key.
I have tried:
let usersRef = firebase.database().ref('users');
usersRef.orderByValue().on("value", function(snapshot) {
console.log(snapshot.val());
snapshot.forEach(function(data) {
console.log(data.key);
});
});
But it brings all the users on the database. Any ideas?
You can use equalTo() to find any child by value. In your case by name:
ref.child('users').orderByChild('name').equalTo('John Doe').on("value", function(snapshot) {
console.log(snapshot.val());
snapshot.forEach(function(data) {
console.log(data.key);
});
});
The purpose of orderByChild() is to define the field you want to filter/search for. equalTo() can get an string, int and boolean value.
Also can be used with auto generated keys (pushKey) too.
You can find all the documentation here
A warning to avoid unpleasant surprises: when you use orderByChild and equalTo do not forget to add an index on your data (here's the doc)
If you don't all the nods will be downloaded and filtered client side which can become very expensive if your database grows.
Related
Im trying to make friends system but in invite accept i have to delete invite of a guy in his list but i cant do it without the key.
How do i get the snapshot key by value (in this case uid) in database?
Firebase Realtime Database queries work on single path, and then order/filter on a value at a fixed path under each direct child node. In your case, if you know whether the user is active or pending, you can find a specific value with:
const ref = firebase.database().ref("friends");
const query = ref.child("active").orderByValue().equalTo("JrvFaTDGV6TnkZq6uGMNICxwGwo2")
const results = query.get();
results.forEach((snapshot) => {
console.log(`Found value ${snapshot.val()} under key ${snapshot.key}`)
})
There is no way to perform the same query across both active and pending nodes at the same time, so you will either have to perform a separate query for each of those, or change your data model to have a single flat list of users. In that case you'll likely store the status and UID for each user as a child property, and use orderByChild("uid").
Also note that using push IDs as keys seems an antipattern here, as my guess is that each UID should only have one status. A better data model for this is:
friends: {
"JrvFaTDGV6TnkZq6uGMNICxwGwo2": {
status: "active"
}
}
I have created a realtime database on firebase and having no issues adding and removing data in tables etc.
I currently have it setup like this:
So my goal is to check if a given value is inside my database currently.
for example, I would like to check if 'max' is currently a username in my database.
var data = db.ref('loginInfo/');
data.on('value', function(snapshot) {
_this.users = snapshot.val()
});
That is how I get all the values, it is saved into _this.users
(How do i check if a value is inside this object, i am making a login program)
if i console.log the object, this is what I see:
image
If you want to check if a child node exists under loginInfo where the username property has a value of max, you can use the following query for that:
var ref = db.ref('loginInfo/');
var query = ref.orderByChild('username').equalTo('max');
query.once('value', function(snapshot) {
console.log(snapshot.exists());
});
I'd also recommend reading the Firebase documentation on queries, as there are many more options.
I am checking if a combination of child values exists in my DB.
This works but can't get the proper message to be displayed in the console.
the correct console message is displayed in both else statements. The one that is not being displayed properly is the console.log('yes').
Or actually it is displayed but always followed by aconsole.log('no') and I have no idea why
There is however a match found because the correct data is shown in console.log(details); console.log(snapshot.key);
FBSearch: function(){
var T1 = this
var T2 = this
var T3 = this
var ref = firebase.database().ref("flights");
ref
.orderByChild('date')
.equalTo(T2.flight.dat)
.on('child_added', function(snapshot) {
var details = snapshot.val();
if (details.flight == T1.flight.flt) {
if(details.origin == T3.flight.org){
console.log(details);
console.log(snapshot.key);
console.log('yes')
} else {
console.log('no')
}
} else {
console.log('no')
}
})
}
The desired outcome is a success message when a match is found
Not sure if this is the answer to your question, but something you might want to consider...
Right now you're reading all flights of the specific date, in an effort to check if one of them exists. This is suboptimal, and can waste lot of your users' bandwidth. Ideally a yes/no question like that should require you to pass in the criteria, and get a minimal yes/no type answer.
While the Firebase Realtime Database doesn't support exists() queries, and can't query on multiple conditions, you can make significant improvements by adding a special property to your data to support this query.
As far as I can see, you're filtering on three properties: date, flight, and origin. I recommend adding an extra property to all flights that combines the values of these properties into a single value. Let's call this property "origin_date_flight".
With that property in place you can run the following query to check for the existence of a certain combination:
ref
.orderByChild('origin_date_flight')
.equalTo(`${T3.flight.org}_${T2.flight.date}_${T1.flight.flt}`)
.limitToFirst(1)
.once('value', function(snapshot) {
if (snapshot.exists()) {
console.log('yes')
} else {
console.log('no')
}
})
The main changes here:
The query uses a composite property as a sort-of index, which allows it to query for the specific combination you're looking for.
The query uses limitToFirst(1). Since you're only looking to see if a value exists, there's no need to retrieve multiple results (if those exist).
The query uses once("value", which allows it to check for both existence and non-existence in a single callback. The child_added event only fired if a match exists, so can't be used to detect non-existence.
And as a bonus, this new property also allow you to for example get all flights out of Amsterdam today:
ref
.orderByChild('origin_date_flight')
.startAt(`AMS_20190728_${T2.flight.date}_`)
.endAt(`AMS_20190728_${T2.flight.date}~`)
.once('value', function(snapshot) {
snapshot.forEach(function(flightSnapshot) {
console.log(flightSnapshot.key+": "+flightSnapshot.child("flt").getValue());
})
})
Also see:
Query based on multiple where clauses in Firebase
how do i grab the PUSH ID generated from firebase push method. I need to store this key in my App.js file for queries in the future. im not sure how to grab this key when the user is already logged in. I posted a pic of what im reffering to, to clarify
To get the pushid based on the email provided, then try the following:
firebase.database().ref().child("users").orderByChild("email").equalTo(yourEmail).on("value", function (snapshot) {
snapshot.forEach(function(childSnapshot) {
var randomKey=childSnapshot.key;
});
});
The snapshot is at the node users then you loop inside the keys and retrieve them using the key property
https://firebase.google.com/docs/reference/js/firebase.database.DataSnapshot#key
I am working on firebase for the first time. I am confused in querying the database. I have two objects on the database, one is the Auth and second one is the Chats. In Auths I have number of UID(user id) nodes, each of these nodes have their respective username. What I am trying to do is, I want to query that Auth object and get all the usernames which is equal to the one I take from a user through input box. In my sql it will be simple as SELECT * FROM auth WHERE username = userInputValue. I need same query like this, Below is what I have done so far.
var _firbaseDB = firebase.database(),
_firebaseAuthRef = _firbaseDB.ref("Auth/");
$("body").on("submit",".search-from",function(e){
e.preventDefault();
var ev = e.target,
_allUsers = $(ev).serializeArray()
_user = _allUsers[0].value;
_firebaseAuthRef.equalTo(_user).on("child_added",function(res){
console.log(res.val());
})
})
You were almost there. What's missing is that you need to specify which attribute you're querying on:
_firebaseAuthRef.orderByChild("n").equalTo(_user).on("child_added",function(res){
console.log(res.val());
})
More info on the Firebase Database Documentation.