Search information by user on firebase - search

Question

This is probably very simple ,so sorry...
I'm trying to create an application where i can create users and store informations by Firebase. There is an example here :
http://image.noelshack.com/fichiers/2015/11/1426182307-log.png
But now I want to check if the name already exists if someone wants to create a new user.
How would I go about grabbing individual user information without knowing their id , like simplelogin:54?
I've found this topic Get users by name property using Firebase but it is not the same thing because in my case I don't know the children after "Users"
Cheers,

Answer 1

Like Frank said, you must know something about the user to be able to look her/him up.
However, here is a general answer. I am assuming that by "name" you mean the property "identifiant" that you've created.
Suggestions
Start by looking over the Firebase Query documentation.
Short Answer
To check if a user exists by the identifiant property, you'd orderByChild("identifiant") and query for a specific user with the .equalTo("<identifient_here>").
For example, to check if a user with identifient="aaa",
var usersRef = new Firebase("https://<YOUR-FIREBASE-APP>.firebaseio.com/Users");
var identifient = "aaa";
usersRef.orderByChild("identifiant").equalTo(identifient).once("value", function(snapshot) {
console.log("Loaded user by identifient:",identifient,snapshot.val());
});
If instead you want to query by the key (such as simplelogin:53), you could query by using orderByKey() instead of orderByChild()... or just simply setting the ref to the user's key like so:
var userKey = 'simplelogin:53';
var userRef = new Firebase("https://<YOUR-FIREBASE-APP>.firebaseio.com/Users" + userKey);
userRef.once("value", function(snapshot) {
console.log("Loaded user",snapshot.val());
});
Long(er) Answer
You can handle this with a user factory (see Angular Providers documentation).
You return a promise in the factory using the $q service.
Here is the Angular API documentation for $q.
Example with UserFactory
Check out this working PLNKR example.
It's tied to one of my public Firebase instances.
I created the same simplelogin:53 user in /Users like you have.
If you search for the identifient = aaa, you'll get the right user.
The controller implementation here is for example purposes, and doesn't really do anything worth while. It's just for reference.
The Data
{
"Users" : {
"simplelogin:53" : {
"identifiant" : "aaa"
}
}
}
UserFactory
.factory('UserFactory', function($q, $firebaseObject, fbUrl){
return function(userId){
var deferred = $q.defer();
if (userId.isNotEmpty()) {
var userRef = new Firebase(fbUrl + '/Users/').orderByChild("identifiant").equalTo(userId);
userRef.once("value",
function(dataSnapshot){
if (dataSnapshot.val()) {
console.log("Loaded user",dataSnapshot.val());
deferred.resolve(dataSnapshot.val());
} else {
console.info("Couldn't find user by id",userId);
deferred.reject("No user found by identifient = '"+userId+"'");
}
},
function(error){
console.error("Error loading user",error);
deferred.reject(error);
}
);
} else {
deferred.reject("No id entered!");
}
return deferred.promise;
}
})
Controller
.controller('HomeController',function($scope, UserFactory) {
$scope.identifient = '';
var showError = function(errorMessage) {
if (errorMessage) {
showUser(false);
$scope.error = errorMessage;
} else {
delete $scope.error;
}
}
var showUser = function (userObject) {
if (userObject) {
showError(false);
$scope.user = userObject;
} else {
delete $scope.user;
}
}
$scope.loadUser = function() {
var userPromise = new UserFactory($scope.identifient);
userPromise.then(function(data){
showUser(data);
}).catch(function(error){
showError(error);
});
}
})
Template
<div ng-controller="HomeController">
<h2>Home Template</h2>
<input ng-model="identifient" placeholder="identifient"/>
<button ng-click="loadUser()">Find User</button>
<hr/>
<div ng-if="user">User: {{user}}</div>
<div ng-if="error">Error: {{error}}</div>
</div>
Hope that helps.