Lawnchair.js not updating data - javascript

I've got a "LocalStore" object for storing data locally. It's based around a Lawnchair object.
var LocalStore = function(name) {
var that = this;
that.name = name;
that.lawnchair = Lawnchair({ name: that.name }, function(store) {
this.before('save', function(record){
console.log("saving " + that.name);
console.log(record);
});
this.after('save', function(record){
console.log("saved " + that.name);
console.log(record);
that.getData(function(records){
console.log("now it's this");
console.log(records);
});
});
});
that.getData = function(callback) {
that.lawnchair.get(that.name, callback);
};
};
LocalStore is then extended with _.extend(from the Underscore.js library) with this method:
save: function(collection, callback) {
this.lawnchair.save({ key:this.name, value: collection }, function(record) {
callback(record);
});
}
This code is used to update a Backbone.js Collection object to Lawnchair. The first time "save" runs for my Users Collection it saves correctly and shows that the object is a simple key/value pair where value is an Array.
Later in my code when a User selects a Default Project, I modify the Users Collection and call "save" again with an updated "defaultProjectId" on the User. The code runs error free, but the after('save') code for Lawnchair runs and shows me that:
- The record object returned is a key/value pair where value is a full Backbone.js Collection with the defaultProjectId property set correctly.
- The getData method that grabs the latest from the Database still shows as a key/value pair with value a simple Array and defaultProjectId is set incorrectly.
I'm at a loss as what to do. It should just be simply calling "lawnchair.save" updates the record, but it just doesn't do it.

Could you try this jsfiddle?
http://jsfiddle.net/QUgtg/1/
I have recreated your code. Instead of a backbone collection, I am passing in an array of objects. This seems to work. You can see the logging output in Firebug.
I have used my own extend code to add the save(). Though honestly, I don't see why you would want to do it that way, instead of just adding a property to the prototype. Your code may differ in that aspect.
If what I have posted works on your end, could you modify that code to show what are you doing differently? If possible, recreate the issue on jsfiddle...

Related

saving fields from multiple documents to an object

I'm using Mongoose for MongoDB operations in my project. I'm trying to:
find every document matching query
create a new object (let's call it objects)
for every document found create a new object inside objects
save fields from found document to created object
And this works just fine. But I also want to:
for every object saved inside my objects find one document matching query in another collection
if document is found, save fields from it to previously created object objects (as new keys)
My code for the second part looks like this:
for(var i in objects) {
if(objects.hasOwnProperty(i)) {
Model.findOne({name: objects[i].name, id: objects[i].id}, function(e, document) {
if(e) console.error(e);
if(document) {
console.log("Found matchind document"); //This is showed for each object, as expected.
objects[i].newField = document.someData;
objects[i].evenNewerField = document.someMoreData;
}
});
}
}
console.log(objects); //This shows old data from previous operations, no new data from the for loop
Your problem is not your mongoose usage, you should take a deep look to Javascript scope and asynchronous. In your code when console.log is called, objects is not yet updated.

Two-way data binding for a Meteor app

I've built an app that is form-based. I want to enable users to partially fill out a form, and then come back to it at a later date if they can't finish it at the present. I've used iron router to create a unique URL for each form instance, so they can come back to the link. My problem is that Meteor doesn't automatically save the values in the inputs, and the form comes up blank when it is revisited/refreshes. I tried the below solution to store the data in a temporary document in a separate Mongo collection called "NewScreen", and then reference that document every time the template is (re)rendered to auto fill the form. However, I keep getting an error that the element I'm trying to reference is "undefined". The weird thing is that sometimes it works, sometimes it doesn't. I've tried setting a recursive setTimeout function, but on the times it fails, that doesn't work either. Any insight would be greatly appreciated. Or, if I'm going about this all wrong, feel free to suggest a different approach:
Screens = new Meteor.Collection('screens') //where data will ultimately be stored
Forms = new Meteor.Collection('forms') //Meteor pulls form questions from here
NewScreen = new Meteor.Collection('newscreen') //temporary storage collection
Roles = new Meteor.Collection('roles'); //displays list of metadata about screens in a dashboard
//dynamic routing for unique instance of blank form
Router.route('/forms/:_id', {
name: 'BlankForm',
data: function(){
return NewScreen.findOne({_id: this.params._id});
}
});
//onRendered function to pull data from NewScreen collection (this is where I get the error)
Template.BlankForm.onRendered(function(){
var new_screen = NewScreen.findOne({_id: window.location.href.split('/')[window.location.href.split('/').length-1]})
function do_work(){
if(typeof new_screen === 'undefined'){
console.log('waiting...');
Meteor.setTimeout(do_work, 100);
}else{
$('input')[0].value = new_screen.first;
for(i=0;i<new_screen.answers.length;i++){
$('textarea')[i].value = new_screen.answers[i];
}
}
}
do_work();
});
//onChange event that updates the NewScreen document when user updates value of input in the form
'change [id="on-change"]': function(e, tmpl){
var screen_data = [];
var name = $('input')[0].value;
for(i=0; i<$('textarea').length;i++){
screen_data.push($('textarea')[i].value);
}
Session.set("updateNewScreen", this._id);
NewScreen.update(
Session.get("updateNewScreen"),
{$set:
{
answers: screen_data,
first: name
}
});
console.log(screen_data);
}
If you get undefined that could mean findOne() did not find the newscreen with the Id that was passed in from the url. To investigate this, add an extra line like console.log(window.location.href.split('/')[window.location.href.split('/').length-1], JSON.stringify(new_screen));
This will give you both the Id from the url and the new_screen that was found.
I would recommend using Router.current().location.get().path instead of window.location.href since you use IR.
And if you're looking for two way binding in the client, have a look at Viewmodel for Meteor.

Copy a Parse.com class to new class with transformation of values

There is an existing Parse.com class that needs to be copied to a new Parse.com class with some new columns and the transformation of one of the columns. The code currently works and uses the Parse.Query.each method to iterate over all records as detailed in the Parse.com documentation but it stops processing at 831 records although there are 12k+ records in the class. This is odd given each should not have a limit and other default limits are 100 or 1000 for find. Should another method be used to iterate over all records or is there something wrong with the code?
var SourceObject = Parse.Object.extend("Log_Old_Class");
var source_query = new Parse.Query(SourceObject);
var TargetObject = Parse.Object.extend("Log_New_Class")
source_query.each(function(record) {
//save record to new class code works fine
var target_query = new TargetObject();
target_query.set("col1_new",record.col1);
target_query.set("col2_new",record.col2);
//etc...
target_query.save(null, {
success: function(obj) {
//SAVED
},
error: function(obj, error) {
//ERROR
}
});
}).then(function() {
//DONE
},
function(error) {
//error
});
One thing that comes to my mind immediately is that the function is getting timed-out. Parse has time limitations on each function. If I were you, I'd first load all the objects in the source class and then add them separately by having a delay between to API calls (server overload issues can also be present).

knockoutjs - ko.mapping.fromJS not working

I have just started trying knockout.js. The ko.mapping offers a nifty way to get and map data from server. However I am unable to get the mapping to work.
I have a simple model:
//var helloWorldModel;
var helloWorldModel = {
name: ko.observable('Default Name'),
message: ko.observable('Hello World Default')
};
$(document).ready(function() {
ko.applyBindings(helloWorldModel);
//a button on the form when clicked calls a server class
//to get json output
$('#CallServerButton').click(getDataFromServer);
});
function getDataFromServer() {
$.getJSON("HelloSpring/SayJsonHello/chicken.json", function(data) {
mapServerData(data);
});
}
function mapServerData(serverData) {
helloWorldModel = ko.mapping.fromJS(serverData, helloWorldModel);
alert(JSON.stringify(serverData));
}
The helloWorldModel has only 2 attributes - exactly the same thing I return from the server. The alert in mapServerData shows -
{"name":"chicken","message":"JSON hello world"}
I have looked up other posts regarding similar problem, but none of them seemed to be solve this issue. Maybe I am missing something very basic - wondering if anyone can point it out.
Also note if I do not declare the model upfront and use
helloWorldModel = ko.mapping.fromJS(serverData);
it is mapping the data to my form correctly.
From Richard's reply and then a little more investigation into this I think that the way I was initializing the model is incorrect. I guess that one cannot use an existing view model and then expect it to work with mapper plugin. So instead you initialize view model with raw JSON data using the ko.mapping.fromJS:
var helloWorldModel;
$(document).ready(function() {
var defaultData = {
name: 'Default Name',
message: 'Hello World Default'
};
helloWorldModel = ko.mapping.fromJS(defaultData);
ko.applyBindings(helloWorldModel);
$('#CallServerButton').click(getDataFromServer);
});
function getDataFromServer() {
$.getJSON("HelloSpring/SayJsonHello/chicken.json", function(data) {
mapServerData(data);
});
}
function mapServerData(serverData) {
alert(JSON.stringify(serverData));
ko.mapping.fromJS(serverData, helloWorldModel);
}
This code works and provides the expected behavior
You can't just overwrite your model by reassigning it this way.
When you do:
ko.applyBindings(helloWorldModel);
You are saying "bind the model helloWorldModel to the page". Knockout then goes through and hooks up the observables in that model and binds them with the page.
Now when you overwrite your form model here:
helloWorldModel = ko.mapping.fromJS(serverData, helloWorldModel);
It is overwriting your model object with a brand new object with entirely new observables in it.
To fix it you need to change this line to just:
ko.mapping.fromJS(serverData, helloWorldModel);
This takes care of the properties inside the model and reassigns them for you, without overwriting your model.

Getting backbone.js to run a function after constructing a Collection?

I may be completely missing something here, but I have the following:
a Model which encapsulates 'all' the data (all JSON loaded from one URL)
the model has one (or more) Collections which it is instantiating with the data it got on construction
some code which I want to run on the Collection when the data is initialized and loaded
My question is about the composed Collection. I could do this outside the scope of the Collection, but I'd rather encapsulate it (otherwise what's the point of making it a 'class' with an initializer etc).
I thought I could put that code in the initialize() function, but that runs before the model has been populated, so I don't have access to the models that comprise the collection (this.models is empty).
Then I thought I could bind to an event, but no events are triggered after initialization. They would be if I loaded the Collection with a fetch from its own endpoint, but I'm not doing that, I'm initializing the collection from pre-existing data.
My question: How to get initialize code to run on the Collection immediately after it is initialized with data (i.e. this.models isn't empty).
Is it possible to do this without having to get 'external' code involved?
Okay here is the demo code, perhaps this will explain things better.
var Everything = Backbone.Model.extend({
url: "/static/data/mydata.json",
parse: function(data)
{
this.set("things", new Things(data.things, {controller: this}));
}
});
var Thing = Backbone.Model.extend({
});
var Things = Backbone.Collection.extend({
model: Thing,
initialize: function(data, options)
{
// HERE I want access to this.models.
// Unfortunately it has not yet been populated.
console.log("initialize");
console.log(this.models);
// result: []
// And this event never gets triggered either!
this.on("all", function(eventType)
{
console.log("Some kind of event happend!", eventType);
});
}
});
var everything = new Everything();
everything.fetch();
// Some manual poking to prove that the demo code above works:
// Run after everything has happened, to prove collection does get created with data
setTimeout(function(){console.log("outside data", everything.get("things").models);}, 1000);
// This has the expected result, prints a load of models.
// Prove that the event hander works.
setTimeout(function(){console.log("outside trigger", everything.get("things").trigger("change"));}, 1000);
// This triggers the event callback.
Unfortunately for you the collection gets set with data only after it was properly initialized first and models are reset using silent: true flag which means the event won't trigger.
If you really wanted to use it you can cheat it a bit by delaying execution of whatever you want to do to next browser event loop using setTimeout(..., 0) or the underscore defer method.
initialize: function(data, options) {
_.defer(_.bind(this.doSomething, this));
},
doSomething: function() {
// now the models are going to be available
}
Digging this an old question. I had a similar problem, and got some help to create this solution:
By extending the set function we can know when the collection's data has been converted to real models. (Set gets called from .add and .reset, which means it is called during the core function instantiating the Collection class AND from fetch, regardless of reset or set in the fetch options. A dive into the backbone annotated source and following the function flow helped here)
This way we can have control over when / how we get notified without hacking the execution flow.
var MyCollection = Backbone.Collection.extend({
url: "http://private-a2993-test958.apiary-mock.com/notes",
initialize: function () {
this.listenToOnce(this, 'set', this.onInitialized)
},
onInitialized:function(){
console.log("collection models have been initialized:",this.models )
},
set: function(models,options){
Backbone.Collection.prototype.set.call(this, models, options);
this.trigger("set");
}
})
//Works with Fetch!
var fetchCollection= new MyCollection()
fetchCollection.fetch();
//Works with initializing data
var colData = new MyCollection([
{id:5, name:'five'},
{id:6, name:'six'},
{id:7, name:'seven'},
{id:8, name:'eight'}
])
//doesn't trigger the initialized function
colData.add(new Backbone.Model({id:9,name:'nine'};
Note: If we dont use .listenToOnce, then we will also get onInitialized called every time a model is added to or changed in the collection as well.

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