I've got a Firebase with a simple bit of data:
There's a list of "players", each with a self-generated GUID, and each containing a value "Count". At my request (e.g. using once()), I want to be able to query the players sorted by the Count value. So, based on the Firebase documentation, I'm using orderByChild(), but it always comes up as undefined when I run the code:
var fb = new Firebase("https://morewhitepixels.firebaseio.com/");
fb.child("players").orderByChild("Count").once("value",function(data) {
// do something with data
});
But this code always returns Uncaught TypeError: undefined is not a function pointing to that second line of code.
What am I missing?
I'm not sure what you do inside the callback, but this works fine:
fb.child("players").orderByChild("Count").once("value",function(data) {
console.log(data.val());
});
Keep in mind that the data parameter is not the actual data yet. It's a DataSnapshot on which you have to call val() first.
You'll probably want to loop through the children, which you can do like this:
fb.child("players").orderByChild("Count").once("value",function(data) {
data.forEach(function(snapshot) {
console.log(snapshot.val().Count);
});
});
The above example prints out all your children in the order you requested:
120320
181425
185227
202488
202488
202488
202488
245197
245197
487320
Alternatively you can use on('child_added' instead:
fb.child("players").orderByChild("Count").on("child_added",function(snapshot) {
console.log(snapshot.val().Count);
});
Related
I have an issue with my cloud functions where in all my database events all return empty. For example, in the following event the event.data.val() would return null. I am doing an update operation and have tested the update by testing the cloud function using the shell as well as after deploying.
export const createSubscription = functions.database.ref('/users/{userId}/subscription').onWrite( event => {
if(!event.data.val()) {
return;
}
});
But I can easily hook into the auth.user() events like the following and receive the data.
export const createStripeUser = functions.auth.user().onCreate(event => {
const user = event.data;
});
Edit: Passing data into the collection for example like the one below on the emulator console
createSubscription({
testKey: 'testValue'
})
or the following on from my frontend
db.ref(`/users/23213213213/subscription`).update({ testKey: 'testValue'});
would return null on the function.
DougStevenson is correct. For the .onCreate() you would be doing it correct wit a myDatabaseFunction('new_data').
With the .onWrite() you need to pass in the before and after like my example below.
You may have got stuck were I did. Note that I have a curly bracket around the before and after the final JSON. It didn't work properly without them.
addComment({before: {"comment":"before comment","role":"guest"}, after:{"comment":"After Comment","role":"guest"}})
Hope my example helps a bit more than a generic string parameter.
Good Luck!
I have a Meteor Helper that does a GET request and am supposed to get response back and pass it back to the Template, but its now showing up the front end. When I log it to console, it shows the value corerctly, for the life of mine I can't get this to output to the actual template.
Here is my helper:
UI.registerHelper('getDistance', function(formatted_address) {
HTTP.call( 'GET', 'https://maps.googleapis.com/maps/api/distancematrix/json? units=imperial&origins=Washington,DC&destinations='+formatted_address+'&key=MYKEY', {}, function( error, response ) {
if ( error ) {
console.log( error );
} else {
var distanceMiles = response.data.rows[0].elements[0].distance.text;
console.log(response.data.rows[0].elements[0].distance.text);
return distanceMiles;
}
});
});
In my template I pass have the following:
{{getDistance formatted_address}}
Again, this works fine and shows exactly what I need in the console, but not in the template.
Any ideas what I'm doing wrong?
I posted an article on TMC recently that you may find useful for such a pattern. In that article the problem involves executing an expensive function for each item in a list. As others have pointed out, doing asynchronous calls in a helper is not good practice.
In your case, make a local collection called Distances. If you wish, you can use your document _id to align it with your collection.
const Distances = new Mongo.collection(); // only declare this on the client
Then setup a function that either lazily computes the distance or returns it immediately if it's already been computed:
function lazyDistance(formatted_address){
let doc = Distances.findOne({ formatted_address: formatted_address });
if ( doc ){
return doc.distanceMiles;
} else {
let url = 'https://maps.googleapis.com/maps/api/distancematrix/json';
url += '?units=imperial&origins=Washington,DC&key=MYKEY&destinations=';
url += formatted_address;
HTTP.call('GET',url,{},(error,response )=>{
if ( error ) {
console.log( error );
} else {
Distances.insert({
formatted_address: formatted_address,
distanceMiles: response.data.rows[0].elements[0].distance.text
});
}
});
}
});
Now you can have a helper that just returns a cached value from that local collection:
UI.registerHelper('getDistance',formatted_address=>{
return lazyDistance(formatted_address);
});
You could also do this based on an _id instead of an address string of course. There's a tacit assumption above that formatted_address is unique.
It's Meteor's reactivity that really makes this work. The first time the helper is called the distance will be null but as it gets computed asynchronously the helper will automagically update the value.
best practice is not to do an async call in a helper. think of the #each and the helper as a way for the view to simply show the results of a prior calculation, not to get started on doing the calculation. remember that a helper might be called multiple times for a single item.
instead, in the onCreated() of your template, start the work of getting the data you need and doing your calculations. store those results in a reactive var, or reactive array. then your helper should do nothing more than look up the previously calculated results. further, should that helper be called more times than you expect, you don't have to worry about all those additional async calls being made.
The result does not show up because HTTP.call is an async function.
Use a reactiveVar in your case.
Depending on how is the formated_address param updated you can trigger the getDistance with a tracker autorun.
Regs
Yann
I am trying to iterate over firebaseObject and firebaseArray fetched from my Firebase but they don't seem like normal javascript objects and arrays.
My data is stored in the following form
'mainKey': {
'key1':'value1',
'key2':'value2'
},
'mainkey2': {
'key3':'value3'
}
I've tried the following code
var firebaseRef = new Firebase("https://<my-app>.firebaseio.com/);
var fbArray = $firebaseArray(firebaseRef);
var fbObject = $firebaseObject(firebaseRef);
for(var i=0;i<fbArray.length;i++){
console.log(fbArray[i]);
}
console.log(fbObject);
console.log(fbObject.mainkey);
console.log(fbArray.length);
This gives the following output in the console
Object { $$conf={...}, $id="test", $priority=null, more...}
undefined
0
Though the object returned has mainkey property but I'm not able to access it.Why does this happen? And how should I iterate over them ?
You could try for..in loop to iterate over an object.
Below is an example:
for (var key in fbObject) {
console.log(fbObject[key]); // You could use this method with all objects in JS
}
here's the info you need to know
The $firebaseArray service takes a Firebase reference or Firebase Query and
returns a JavaScript array which contains the data at the provided Firebase
reference. Note that the data will not be available immediately since
retrieving it is an asynchronous operation.
You can use the $loaded() promise to get notified when the data has loaded.
https://www.firebase.com/docs/web/libraries/angular/api.html#angularfire-firebasearray
fbArray.$loaded(function() {
//here you can iterate over your object
});
I'd like to create a method that returns the count of a generic collection.
Calling the method would look something like this:
Meteor.call('getCollectionCount', 'COLLECTION_NAME');
And the result would be the collection count.
The server method code would look something like this:
getCollectionCount: function (collectionName) {
return window[collectionName].find().count();
}
This won't work because window isn't defined on the server, but is something similar possible?
Use global instead of window.
Note that this uses the variable name assigned to the collection object, not the name given to the collection. For this to work with Meteor.users you need to assign another variable name.
if (Meteor.isServer) {
users = Meteor.users;
}
if (Meteor.isClient) {
Meteor.call('count', 'users', function (err, res) {
// do something with number of users
});
}
Also probably a good idea to check that global[collectionName] is actually a collection.
I came up with this code which makes the following assumptions :
collections are declared in the global scope as top level objects.
collections are searched by collection name, not the collection variable identifier.
So client code should declare their collections like this :
MyCollection=new Meteor.Collection("my-collection");
And use the function like this :
var clientResult=Meteor.call("getCollectionCount","my-collection",function(error,result){
if(error){
console.log(error);
return;
}
console.log("actual server-side count is : ",result);
});
console.log("published subset count is : ",clientResult);
The method supports execution on the client (this is known as method stub or method simulation) but will only yield the count of the collection subset replicated client-side, to get the real count wait for server-side response using a callback.
/packages/my-package/lib/my-package.js
getCollection=function(collectionName){
if(collectionName=="users"){
return Meteor.users;
}
var globalScope=Meteor.isClient?window:global;
for(var property in globalScope){
var object=globalScope[property];
if(object instanceof Meteor.Collection && object._name==collectionName){
return object;
}
}
throw Meteor.Error(500,"No collection named "+collectionName);
};
Meteor.methods({
getCollectionCount:function(collectionName){
return getCollection(collectionName).find().count();
}
});
As Meteor.users is not declared as a top level variable you have to account for the special case (yes, this is ugly).
Digging into Meteor's collection handling code could provide a better alternative (getting access to a collection handle by collection name).
Final words on this : using a method call to count a collection documents is unfortunately non-reactive, so given the Meteor paradigm this might be of little use.
Most of the time you will want to fetch the number of documents in a collection for pagination purpose (something like a "Load more" button in a posts list for example), and as the rest of the Meteor architecture you'll want this to be reactive.
To count documents in a collection reactively you'll have to setup a slightly more complicated publication as showcased in the "counts-by-room" example in the docs.
http://docs.meteor.com/#meteor_publish
This is something you definitely want to read and understand.
This smart package is actually doing it right :
http://atmospherejs.com/package/publish-counts
It provides a helper function that is publishing the counts of any cursor.
Keep track of the collections on some other property that the server has access too. You could even call it window if you really wanted to.
var wow = new Meteor.Collection("wow");
collections["wow"] = wow;
getCollectionCount: function (collectionName) {
return collections[collectionName].find().count();
}
If you don't want the package users to change how they work with collections in the app then I think you should use MongoInternals to get collections by name from the db. Not tested but here is an example:
//on server
Meteor.methods({
count: function( name ){
var db = MongoInternals.defaultRemoteCollectionDriver().mongo.db;
var collection = db.collection( name );
return collection && collection.count({});
}
});
Another example of MongoInternals use is here. Documentation of the count() function available from the mongo driver is here.
I have no issues when using implicit updates (angelFire). However I need for some of my data use explicit updating. So I implemented angelFireCollection on the exact same ref I was using previously but despite the console.log explicitly saying that the read was granted and trying it with both with the onloadcallback and without, I don't get data directly into my assigned variable AND once the callback fires I get a strange looking object that DOES contain the data but not in the form I expect. My scope variable ends up with an empty collection. Never gets populated. Here is the code:
var streamController = function ($rootScope, $scope, $log, $location, angularFireCollection, profileService) {
//Wait for firebaseLogin...
$rootScope.$watch('firebaseAuth', init);
function init() {
if ($rootScope.firebaseAuth == false) {
return
};
var refUsers = new Firebase($rootScope.FBURL+'/users/'+$rootScope.uid);
$scope.profile = angularFireCollection(refUsers, function onload(snapshot) {
console.log(snapshot)
});
};
};
myApp.gwWebApp.controller('StreamController', ['$rootScope', '$scope', '$log', '$location', 'angularFireCollection', 'profileService',
streamController]);
}());
Here is what the console.log looks like ( ie; what snapshot looks like ):
>snapshot
T {z: R, bc: J, V: function, val: function, xd: function…}
Here is the earlier message before the snapshot was returned:
Firebase Login Succeeded! fbLoginController.js:16
FIREBASE: Attempt to read /users/529ccc5d1946a93656320b0a with auth={"username":"xxxxxxx#me.com","id":"529ccc5d1946a93656320b0a"} firebase.js:76
FIREBASE: /: "auth.username == 'admin'" firebase.js:76
FIREBASE: => false firebase.js:76
FIREBASE: /users firebase.js:76
FIREBASE: /users/529ccc5d1946a93656320b0a: "auth.id == $user" firebase.js:76
FIREBASE: => true firebase.js:76
FIREBASE:
FIREBASE: Read was allowed.
and finally the desired binding that ends up with an empty array: again from the console:
$scope.profile
[]
Anyone know what I could possibly be doing wrong?? This is like 5 lines of code. Frustrating.
I have put stops in angelFireCollection factory function and can see that the data is getting added to the collection in the callbacks inside that function but my binded variable never gets updated.
UPDATE
Ok experimenting with a plnkr. It seems that angularFireCollection EXPECTS your returning a LIST of items. The snapshot returns properly if you inspect snapshot.val() it will be whatever object structure was stored in firebase. IF you use angularFireCollection it does indeed bind to the variable HOWEVER it turns a non-list object into a garbled mess and you can not access the object user the normal dot operator. This is either a bug or it is a severe limitation of angularFireCollection which will cause me to revaluate how easily I can use firebase as the backend. I can't share my plnkr because it is accessing non-public data but tomorrow if i have time I will create a public firebase with an object store and demonstrate.
Ok. So it appears that indeed angularFireCollection is MEANT to be array based. Which is fine. It would be VERY helpful if the angularFire documentation was updated to make that clear. As such it is not an implicit vs explicit update technique.
For an explicit non-array based approach I have come up with the following code. Had I not been mislead by the documentation I would have gone down this path originally.
var MainCtrl = function($scope, angularFire) {
$scope.test = {};
var _url = 'https://golfwire.firebaseio.com/tmp';
var _ref = new Firebase(_url);
var promise = angularFire(_ref, $scope, 'implicit');
promise.then ( function(data){
$scope.explicit=angular.copy($scope.implicit );
});
}
You then work locally with the 'explicit' copy and when ready just update the 'implicit' by assigning: $scope.implicit = $scope.explicit.
Here is a plnkr: http://plnkr.co/edit/bLJrL1