Develop Reference

Optimalization of firebase query. Getting data by ids

I'm new in Firebase. I would like to create an app (using Angular and AngularFire library), which shows current price of some wares. I have list all available wares in Firebase Realtime Database in the following format:
"warehouse": {
"wares": {
"id1": {
"id": "id1",
"name": "name1",
"price": "0.99"
},
"id2": {
"id": "id2",
"name": "name2",
"price": "15.00"
},
... //much more stuff
}
}
I'm using ngrx with my app, so I think that I can load all wares to store as an object not list because normalizing state tree. I wanted load wares to store in this way:
this.db.object('warehouse/wares').valueChanges();
The problem is wares' price will be refresh every 5 minutes. The number og wares is huge (about 3000 items) so one response will be weight about 700kB. I know that I will exceed limit downloaded data in a short time, in this way.
I want limit the loading data to interesing for user, so every user will can choose wares. I will store this choices in following way:
"users": {
"user1": {
"id": "user1",
"wares": {
"id1": {
"order": 1
},
"id27": {
"order": 2
},
"id533": {
"order": 3
}
},
"waresIds": ["id1", "id27", "id533"]
}
}
And my question is:
Is there a way to getting wares based on waresIds' current user? I mean, does it exist way to get only wares, whose ids are in argument array? F.e.
"wares": {
"id1": {
"id": "id1",
"name": "name1",
"price": "0.99"
},
"id27": {
"id": "id27",
"name": "name27",
"price": "0.19"
},
"id533": {
"id": "id533",
"name": "name533",
"price": "1.19"
}
}
for query like:
this.db.object('warehouse/wares').contains(["id1", "id27", "id533"]).valueChanges();
I saw query limits in Angular Fire like equalTo and etc. but every is for list. I'm totally confused. Is there anyone who can help me? Maybe I'm making mistakes in the design of the app structure. If so, I am asking for clarification.

Because you are saving the ids inside user try this way.
wares: Observable<any[]>;
//inside ngOnInit or function
this.wares = this.db.list('users/currentUserId/wares').snapshotChanges().map(changes => {
return changes.map(c => {
const id = c.payload.key; //gets ids under users/wares/ids..
let wares=[];
//now get the wares
this.db.list('warehouse/wares', ref => ref.orderByChild('id').equalTo(id)).valueChanges().subscribe(res=>{
res.forEach(data=>{
wares.push(data);
})
});
return wares;
});
});

There are two things you can do. I don't believe Firebase allows you to query for multiple equals values at once. You can however loop over the array of "ids" and query for each one directly.
I am assuming you already queried for "waresIds" and you've stored those ID's in an array named idArray:
for id in idArray {
database.ref('warehouse/wares').orderByChild('id').equalTo(id).once('value').then((snapshot) => {
console.log(snapshot.val());
})
}
In order to use the above query efficiently you'll have to index your data on id.
Your second option would be to use .childChanged to get only the updated data after your initial fetch. This should cut down drastically on the amount of data you need to download.

Yes , you can get exactly data that you want in firebase,
See official Firebase documents about filtering
You need to get each waresID
var waresID = // logic to get waresID
var userId = // logic to get userId
var ref = firebase.database().ref("wares/" + userId).child(waresID);
ref.once("value")
.then(function(snapshot) {
console.log(snapshot.val());
});
this will return only data related to that waresID or userId
Note: this is javascript code, i hope this will work for you.

How to export json object into excel using javascript or jquery?

I wanted to export my json object into excel file. I have searched in Google and tried the following, but I am unable to get or export my object data into excel file on clicking of button, it is downloading but without any columns/data(i.e empty file is downloading).
I am not sure what is the problem, Please someone help me regarding this. Thanks in advance !
Created Plnkr.
html:
<div id="dvjson"></div>
<br><button type="button" id='DLtoExcel'>
Download CSV
</button>
js:
$(document).ready(function(){
//if I give below json object, file is downloading with the columns/data and hence it is fine
//var testjsondata = [{"number":123}];
//if I give like below object, empty file is downloading, not having any data
//it is not working //it should also work
//var testjsondata = {"number": 123}//it is not working //it should also work
//and the following object format also should work
var testjsondata = {
"test": {
"name": "abc",
"address": [{
"number": "12345",
"street": "xyz"
}]
},
"mynumber": 12
};
var $btnDLtoExcel = $('#DLtoExcel');
$btnDLtoExcel.on('click', function () {
$("#dvjson").excelexportjs({
containerid: "dvjson"
, datatype: 'json'
, dataset: testjsondata
, columns: getColumns(testjsondata)
});
});
console.log(testjsondata);
});
Any other solutions or libraries also welcome, my json object is plain type, not any array type.

How to insert new child data in Firebase web app?

I am building a simple car database app. When a user adds a new car it creates the below JSON data with blank fields for the gallery:
{
"name": "Cars",
"gallery": [{
"img": "http://",
"title": "BMW"
}, {
"img": "http://",
"title": "Lexus"
}, {
"img": "http://",
"title": "Ferrari"
}],
"pageId": "23",
"storeURL": "/app/cars/gallery"
}
Now what I want to do in the app is if a user adds a new gallery image it should add new child after the last gallery picture. So after Ferrari it should insert a new object. I cannot seem to do this as every tutorial leads to a dead end and also the official Google docs specify that set() will replace all data so if you use update() it will add and in this case it does not add.
This code deletes all data:
function add(){
var data = [
{
title: 'Mercedes',
img: 'http://'
}
]
var postData = {
pageGallery: data
};
var updates = {};
updates['/app/cars/'] = postData;
firebase.database().ref().update(updates);
console.log('New car added');
}
And if I change and add the child:
firebase.database().ref().child('gallery').update(updates);
It does not do anything to do the data. Please can you help?

See this blog post on the many reasons not use arrays in our Firebase Database. Read it now, I'll wait here...
Welcome back. Now that you know why your current approach will lead to a painful time, let's have a look at how you should model this data. The blog post already told you about push IDs, which are Firebase's massively scalable, offline-ready approach to array-like collections.
As our documentation on reading and writing lists of data explains, you can add items to a list by calling push().
So if this creates a car:
function addStore(){
var rootRef = firebase.database().ref();
var storesRef = rootRef.child('app/cars');
var newStoreRef = storesRef.push();
newStoreRef.set({
name: "Cars",
"pageId": "23",
"storeURL": "/app/cars/gallery"
});
}
Then to add an image to the gallery of that store:
var newCarRef = newStoreRef.child('gallery').push();
newCarRef.set({
title: 'Mercedes',
img: 'http://'
})
This will add a new car/image to the end of the gallery (creating the gallery if it doesn't exist yet).

If somebody wants it With Error Handling :
var rootRef = firebase.database().ref();
var storesRef = rootRef.child('Lorelle/Visitors');
var newStoreRef = storesRef.push();
newStoreRef.set($scope.CarModal,
function(error) {
//NOTE: this completion has a bug, I need to fix.
if (error) {
console.log("Data could not be saved." + error);
Materialize.toast('Error: Failed to Submit' + error, 2000);
} else {
console.log("Data saved successfully.");
Materialize.toast('Data Submitted, Thank You.', 2000);
}
});
}

Backbone and best practice getting config JSON

I've got a JSON file that looks like this.
{
"config": {
"setting1": 'blabla',
"setting2": 'blablabla'
},
"content": {
"title": "Title of an exercise.",
"author": "John Doe",
"describtion": "Exercise content."
},
"answers": [
{
"id": "1",
"content": "Dog",
"correct": true
},
{
"id": "2",
"content": "Fish",
"correct": false
}
]
}
Than, I create a Backbone View, combined from content model, and answers (which are randomly selected, but It's not most important now).
I've also got a config, which has settings that will determinate which view and collection methods to use.
It seems like a simple task, but as I'm new to Backbone, I'm wondering which is the best way to fetch JSON file, creating one model with url to JSON and than using parse and initialize creating another models and collections (with answers), or using $.getJSON method that will create exactly the models that I need?
I was trying using $.getJSON
$.getJSON(source, function(data) {
var contentModel = new ContentModel(data.content);
var contentView = new ExerciseView({ model: contentModel });
var answerCollection = new AnswersCollection();
_.each(data.answers, function(answer) {
answerCollection.add(answer);
});
var answersView = new AnswersView({collection: answerCollection});
$(destination).html( contentView.render().el );
$('.answers').append( answersView.el );
)};
But It doesn't seem very elegant solution, I know that this application needs good architecture, cause It will be developed with many other Views based on 'config'.
Hope you guys give me some suggestions, have a good day!

I think what you've done works fine and is correct. But you may need to refactor a little bit since "it will be developed with many other Views based on 'config'".
IMHO, the first thing you need to do is to handle failure in your getJson callback to make the process more robust.
Second, it is useful to create a Factory to generate your views because your logic is to generate different views based on the config data from server. So the factory maybe:
contentViewFactory.generate = function(data) {
var config = data.config;
....
var ActualContentView = SomeContentView;
var contentModel = new ContentModel(data.content);
return = new ActualContentView({ model: contentModel });
}
If your logic is simple, you can have a dict map from config to view class like:
var viewMaps = {
"exercise" : ExerciseView,
"other": SomeOtherView,
//....
}
And if every workflow has a AnswersView you can keep that in your getJSON callback. So maybe now your getJSON looks like this:
$.getJSON(source, function(data) {
// keep the config->view logic in the factory
var contentView = contentViewFactory.generate(data);
var answerCollection = new AnswersCollection();
_.each(data.answers, function(answer) {
answerCollection.add(answer);
});
var answersView = new AnswersView({collection: answerCollection});
$(destination).html( contentView.render().el );
$('.answers').append( answersView.el );
})
.fail(){
//some failure handling
};
Furthermore, if you have common logics in you "ContentView"s, it's natural that you can have a "BaseContentView" or "ContentViewMixin" to extract the common logic and use extends to make your code more OO:
Backbone.View.extend(_.extend({}, ContentViewMixin, {
//.....
}
So if someone is trying to add a new ContentView, he/she just needs to add some code in the factory to make the new View be generated by config. Then extends the ContentViewMixin to implement the new View.

Iteration in handlebar using backbone

I'm using backbone and handlebars for templating and i'm new to this.
My current json is in the below format and the code works fine.
[
{
"id": "10",
"info": {
"name": "data10"
}
},
{
"id": "11",
"info": {
"name": "data11"
}
}
]
But when i change my json structure to something like shown below i'm having difficulty in getting things to be populated.
{
"total_count": "10",
"dataElements": [
{
"id": "10",
"info": {
"name": "data10"
}
},
{
"id": "11",
"info": {
"name": "data11"
}
}
]
}
How can i populate name, info and total_count keeping the current code structure ?
JSFiddle : http://jsfiddle.net/KTj2K/1/
Any help really appriciated.

A few things that you need to do in order for this to work.
Replace Backbone's core 'reset' on your collection with a custom one that understands the data you are passing to it. For example:
reset: function (data) {
this.totalCount = data.total_count;
Backbone.Collection.prototype.reset.call(this, data.dataElements);
}
Now when you reset your collection, it will pull the total_count out of the object you are resetting it with, and use Backbone's core reset with the dataElement array. Keep in mind you may have to do a similar thing with 'parse' if you're intending on pulling this from the server.
I'd recommend that (if your example looks anything like the real code you're working with) you reset your collection before getting to rendering.
var dataCollectionList = new dataCollection();
dataCollectionList.reset(jsonData);
var App = new AppView({model : dataCollectionList});
Now in your view's "render" method you can grab the 'totalCount' property off the collection -
render : function() {
//Should spit the total count into the element, just as an example
this.$el.append(this.model.totalCount);
//or console.log it
console.log(this.model.totalCount);
return this;
}
Voila. Side note - as someone who works with Backbone a lot, it drives me nuts when people set an attribute of something like "model" (i.e. peopleModel, itemModel, etc) and it ends up being a backbone collection. It's much clearer to name it after what it is - though some MVC purists may disagree a bit.
Also, in this code block:
_.each(this.model.models, function (myData) {
$(this.el).append(new ItemView({model:myData}).render().el);
}, this);
You don't need to do _.each(this.model.models.......). Since you're working with a collection, the collection has a built in 'each' method.
this.model.each(function (myData) { ..... } , this);
Quite a bit cleaner.