Develop Reference

Displaying a stream of incoming data - cannot access property of undefined

EDIT
This is the log for my request
$("#search_button").click(function(){
var search = document.getElementById('search_text').value;
$.post('http://127.0.0.1:5000/search', {search_text: search, num_results: 2}, function(data, textStatus, xhr) {
console.log(data);
});
});
Background
I'm fetching some data from my server and trying to display it on my page using the Onsen UI framework's Infinite List but I'm getting a cannot access property 'text' of undefined error. I do see the data using console.log(data) so I hope there's not a problem with the request. I would really appreciate if someone could explain me what am I doing wrong here? Thanks
This Works
I tried a basic example before fetching the data
ons.ready(function() {
var data = [{"text":"Title 1"}, {"text":"Title 2"}]
var infiniteList = document.getElementById('infinite-list');
infiniteList.delegate = {
createItemContent: function(i) {
return ons.createElement(`<ons-list-item>
<p style="color:DodgerBlue;">`+data[i].text+`</p>
<img style="width:100%;" src="http://images.all-free-download.com/images/graphiclarge/beautiful_scenery_04_hd_pictures_166258.jpg"/>
</ons-list-item>`);
},
countItems: function() {
return data.length;
}
};
infiniteList.refresh();
});
This doesnt work
ons.ready(function(){
$("#test_button").click(function(){
$.post('http://127.0.0.1:5000/search', {search_text: 'car', num_results: 2}, function(data, textStatus, xhr) {
/*after success */
var infiniteList = document.getElementById('infinite-list');
infiniteList.delegate = {
createItemContent: function(i) {
return ons.createElement(`<ons-list-item>
<p style="color:DodgerBlue;">`+data[i]+`</p>
<img style="width:100%;" src="http://images.all-free-download.com/images/graphiclarge/beautiful_scenery_04_hd_pictures_166258.jpg"/>
</ons-list-item>`);
},
countItems: function() {
return 2;
}
};
infiniteList.refresh();
});
});
});

'Data' is limited to the function in which it is visible; it needs to be recognized where you are using it as well.
Use another variable which is declared outside both functions.
var dataUse = [];//----------declare here so it is visible in every scope
ons.ready(function(){
$("#test_button").click(function(){
$.post('http://127.0.0.1:5000/search', {search_text: 'car', num_results: 2}, function(data, textStatus, xhr) {
/*after success */
dataUse = data;
var infiniteList = document.getElementById('infinite-list');
infiniteList.delegate = {
createItemContent: function(i) {
return ons.createElement(`<ons-list-item>
<p style="color:DodgerBlue;">`+dataUse[i]+`</p>
<img style="width:100%;" src="http://images.all-free-download.com/images/graphiclarge/beautiful_scenery_04_hd_pictures_166258.jpg"/>
</ons-list-item>`);
},
countItems: function() {
return 2;
}
};
infiniteList.refresh();
});
});
});

Creating a jQuery container to hold other functions

I am trying to create a simple class or a container to hold few JavaScript methods as shown below.
var Core = (function () {
var Error = {
alert: function() {
alert('Error => alert called');
},
display: function() {
alert('Error => display called');
}
};
var ajax = {
view: function(){
alert('Ajax => view called');
},
update: function(){
alert('Ajax => update called');
}
};
var call = function(){
Error.alert();
Error.display();
ajax.view();
ajax.update();
};
$(document).ready(function(){
call(); // This works fine.
}());
But for some reason I am not able to call these methods outside the container. For instance calling functions as shown below throws error.
$(document).ready(function(){
Core.Error.alert(); // This doesn't work.
Core.Call(); // This doesn't work.
});
Error: Uncaught TypeError: Cannot read property 'Error' of undefined
I can call the functions from within the container. I am new to the concept of jQuery plugins and would appreciate if someone can help me with this.

You can export these methods (read more about Module Pattern), like so
var Core = (function () {
...
return {
Error: Error,
Ajax: ajax,
Call: call
};
})();
Core.Error.alert();
Core.Call();
Example

Change it in:
var Core = {
error: {
alert: function () {
alert('Error => alert called');
},
display: function () {
alert('Error => display called');
}
},
ajax: {
view: function () {
alert('Ajax => view called');
},
update: function () {
alert('Ajax => update called');
}
},
call: function () {
Core.error.alert();
Core.error.display();
Core.ajax.view();
Core.ajax.update();
}
}
$(document).ready(function () {
Core.call(); // This works
}());
Working fiddle

Failed to load routed module requirejs? durandal bug?

I created an Asp.Net MVC and used nuget to add HotTowel (V2.0.1 of 9/11/2013). I created a couple of ViewModel, Models. However, I got the following error.
"Failed to load routed module (viewmodels/myVM). Details: Load timeout for modules: durandal/plugins/router\nhttp://requirejs.org/docs/errors.html#timeout"
Is it the problem of durandal/plugins/router? Or it can be caused by some code I added?
The error occurred at Scripts/durandal/system.js.
var logError = function(error) {
if(error instanceof Error){
throw error;
}
throw new Error(error);
};
The following is the VM code.
define(['services/datacontext', 'durandal/plugins/router', 'services/logger'],
// Remove the durandal/plugins/router and the functions will get rid of the error.
function (datacontext, router, logger) {
var title = 'Event';
var vm = {
activate: activate,
deactivate: deactivate,
refresh: refresh,
events: events,
title: title
};
return vm;
//#region Internal Methods
var events = ko.observableArray();
function activate() {
logger.log(title + ' View Activated', null, title, true);
return datacontext.getEventPartials(events);
}
var deactivate = function () {
events([]);
};
var refresh = function () {
return datacontext.getEventPartials(events, true);
};
//#endregion
});
The following is the call stack
logError [system.js] Line 92 Script
Anonymous function [router.js] Line 359 Script
[External Code]
Anonymous function [system.js] Line 260 Script
[External Code]
[Async Call]
....
Code at router.js,
isProcessing(true);
router.activeInstruction(instruction);
if (canReuseCurrentActivation(instruction)) {
ensureActivation(activator.create(), currentActivation, instruction);
} else {
system.acquire(instruction.config.moduleId).then(function(module) {
var instance = system.resolveObject(module);
ensureActivation(activeItem, instance, instruction);
}).fail(function(err){
system.error('Failed to load routed module (' + instruction.config.moduleId + '). Details: ' + err.message);
});
}
}
And previous one in system.js.
acquire: function() {
var modules,
first = arguments[0],
arrayRequest = false;
if(system.isArray(first)){
modules = first;
arrayRequest = true;
}else{
modules = slice.call(arguments, 0);
}
return this.defer(function(dfd) {
require(modules, function() {
var args = arguments;
setTimeout(function() {
if(args.length > 1 || arrayRequest){
dfd.resolve(slice.call(args, 0));
}else{
dfd.resolve(args[0]);
}
}, 1);
}, function(err){
dfd.reject(err);
});
}).promise();
},

Based on the comments I'd recommend to modify the vm code slightly, so that all variables that are returned via vm are defined before use. In addition 'plugins/router' is used instead of 'durandal/plugins/router'.
define(['services/datacontext', 'plugins/router', 'services/logger'],
// Remove the durandal/plugins/router and the functions will get rid of the error.
function (datacontext, router, logger) {
var title = 'Event';
var events = ko.observableArray();
var deactivate = function () {
events([]);
};
var refresh = function () {
return datacontext.getEventPartials(events, true);
};
var vm = {
activate: activate,
deactivate: deactivate,
refresh: refresh,
events: events,
title: title
};
return vm;
//#region Internal Methods
function activate() {
logger.log(title + ' View Activated', null, title, true);
return datacontext.getEventPartials(events);
}
//#endregion
});
BTW the name Internals methods is misleading as everything in that region is returned via vm. I prefer to work with named function instead, which get created before the return statement if they are returned and place them below the return statement in a Internal methods region if they are not returned.
define(['services/datacontext', 'plugins/router', 'services/logger'],
function( datacontext, router, logger ) {
var title = 'Event';
var events = ko.observableArray();
function deactivate () {
events([]);
}
function refresh () {
return datacontext.getEventPartials(events, true);
}
function activate () {
logger.log(title + ' View Activated', null, title, true);
return datacontext.getEventPartials(events);
}
return {
activate: activate,
deactivate: deactivate,
refresh: refresh,
events: events,
title: title
};
//#region Internal Methods
//#endregion
});

Backbone - Validation not working on create, only update/edit?

So, I am able to validate just fine when I am editing an existing item. However, if I want to create, validation for some reason is not getting kicked off. Instead, I am seeing the errors below:
//this is if the field I want to validate is empty
Uncaught TypeError: Object #<Object> has no method 'get'
//this is if everything in the form is filled out
Uncaught TypeError: Cannot call method 'trigger' of undefined
Here is(what I think is) the relative portion of my js. Sorry if its an overload, I wanted to add as much as I can to be as specific as possible:
Comic = Backbone.Model.extend({
initialize: function () {
this.bind("error", this.notifyCollectionError);
this.bind("change", this.notifyCollectionChange);
},
idAttribute: "ComicID",
url: function () {
return this.isNew() ? "/comics/create" : "/comics/edit/" + this.get("ComicID");
},
validate: function (atts) {
if ("Name" in atts & !atts.Name) {
return "Name is required";
}
if ("Publisher" in atts & !atts.Publisher) {
return "Publisher is required";
}
},
notifyCollectionError: function (model, error) {
this.collection.trigger("itemError", error);
},
notifyCollectionChange: function () {
this.collection.trigger("itemChanged", this);
}
});
Comics = Backbone.Collection.extend({
model: Comic,
url: "/comics/comics"
});
comics = new Comics();
FormView = Backbone.View.extend({
initialize: function () {
_.bindAll(this, "render");
this.template = $("#comicsFormTemplate");
},
events: {
"change input": "updateModel",
"submit #comicsForm": "save"
},
save: function () {
this.model.save(
this.model.attributes,
{
success: function (model, response) {
model.collection.trigger("itemSaved", model);
},
error: function (model, response) {
model.trigger("itemError", "There was a problem saving " + model.get("Name"));
}
}
);
return false;
},
updateModel: function (evt) {
var field = $(evt.currentTarget);
var data = {};
var key = field.attr('ID');
var val = field.val();
data[key] = val;
if (!this.model.set(data)) {
//reset the form field
field.val(this.model.get(key));
}
},
render: function () {
var html = this.template.tmpl(this.model.toJSON());
$(this.el).html(html);
$(".datepicker").datepicker();
return this;
}
});
NotifierView = Backbone.View.extend({
initialize: function () {
this.template = $("#notifierTemplate");
this.className = "success";
this.message = "Success";
_.bindAll(this, "render", "notifySave", "notifyError");
comics.bind("itemSaved", this.notifySave);
comics.bind("itemError", this.notifyError);
},
events: {
"click": "goAway"
},
goAway: function () {
$(this.el).delay(0).fadeOut();
},
notifySave: function (model) {
this.message = model.get("Name") + " saved";
this.render();
},
notifyError: function (message) {
this.message = message;
this.className = "error";
this.render();
},
render: function () {
var html = this.template.tmpl({ message: this.message, className: this.className });
$(this.el).html(html);
return this;
}
});
var ComicsAdmin = Backbone.Router.extend({
initialize: function () {
listView = new ListView({ collection: comics, el: "#comic-list" });
formView = new FormView({ el: "#comic-form" });
notifierView = new NotifierView({el: "#notifications" });
},
routes: {
"": "index",
"edit/:id": "edit",
"create": "create"
},
index: function () {
listView.render();
},
edit: function (id) {
listView.render();
$(notifierView.el).empty();
$(formView.el).empty();
var model = comics.get(id);
formView.model = model;
formView.render();
},
create: function () {
var model = new Comic();
listView.render();
$(notifierView.el).empty();
$(formView.el).empty();
formView.model = model;
formView.render();
}
});
jQuery(function () {
comics.fetch({
success: function () {
window.app = new ComicsAdmin();
Backbone.history.start();
},
error: function () {
}
});
})
So, shouldnt my create be getting validated too? Why isnt it?

When creating a new instance of a model, the validate method isn't called. According to the backbone documentation the validation is only called before set or save.
I am also struggling with this problem and found solutions in related questions:
You could make a new model and then set its attributes (see question 9709968)
A more elegant way is calling the validate method when initializing the model (see question 7923074)
I'm not completely satisfied with these solutions because creating a new instance of the model like described in the backbone documentation shouldn't happen when an error is triggered. Unfortunately, in both solutions you're still stuck with a new instance of the model.
edit: Being stuck with a new instance of the model is actually quite nice. This way you can give the user feedback about why it didn't pass the validator and give the opportunity to correct his/her input.

OK. So, I'm having some mild success here.
First, I wrote my own validation framework, Backbone.Validator since I didn't like any of the ones out there that I found.
Second, I am able to get the validation framework to set off the validation routine by setting silent: false with in the object provided during the new Model creation.
Along with using the use_defaults parameter from my validation framework I am able to override bad data during setup in initial testing. I'm still working on doing some more tests on this, but it seems to be going OK from from the Chrome browser console.

Backbonejs when to initialize collections

I'm building small one page application with rails 3.1 mongodb and backbonejs.
I have two resources available through json api. I created two models and collections in backbone which look like this
https://gist.github.com/1522131
also I have two seprate routers
projects router - https://gist.github.com/1522134
notes router - https://gist.github.com/1522137
I generated them with backbonejs-rails gem from github so code inside is just template. I initialize my basic router inside index.haml file
#projects
:javascript
$(function() {
window.router = new JsonApi.Routers.ProjectsRouter({projects: #{#projects.to_json.html_safe}});
new JsonApi.Routers.NotesRouter();
Backbone.history.start();
});
I don't want fetch notes when application is starting, because there is big chance that user will never look inside notes. So there isn't good reason to fetch it on start. Inside NotesRouter in all action I rely on #notes variable but without .fetch() method this variable is empty. Also I should can reproduce notes view from url like
/1/notes/5
project_id = 1
note_id = 5
What is best practices in backbonejs to solve this kind of problem ?

Why don't you lazy load the notes when it's requested? Here's an example:
var State = Backbone.Model.extend({
defaults: {
ready: false,
error: null
}
});
var Note = Backbone.Model.extend({
initialize: function () {
this.state = new State();
}
});
var Notes = Backbone.Collection.extend({
model: Note,
initialize: function () {
this.state = new State();
}
});
var NoteCache = Backbone.Model.extend({
initialize: function () {
this._loading = false;
this._loaded = false;
this._list = new Notes();
},
_createDeferred: function (id) {
var note = new Note({ id: id });
this._list.add(note);
this._load();
return note;
},
getNote: function (id) {
return this._list.get(id) || this._createDeferred(id);
},
getNotes: function () {
if (!this._loaded)
this._load();
return this._list;
},
_load: function () {
var that = this;
if (!this._loading) {
this._list.state.set({ ready: false, error: null });
this._loading = true;
$.ajax({
url: '/api/notes',
dataType: 'json',
cache: false,
type: 'GET',
success: function (response, textStatus, jqXHR) {
_.each(response.notes, function (note) {
var n = that._list.get(note.id);
if (n) {
n.set(note);
} else {
that._list.add(note, { silent: true });
n = that._list.get(note.id);
}
n.state.set({ ready: true, error: null });
});
that._list.state.set({ ready: true, error: null });
that._list.trigger('reset', that._list);
that._loaded = true;
},
error: function (jqXHR, textStatus, errorThrown) {
that._list.state.set({ error: 'Error retrieving notes.' });
that._list.each(function (note) {
note.state.set({ error: 'Error retrieving note.' });
});
},
complete: function (jqXHR, textStatus) {
that._loading = false;
}
});
}
}
});
In this example, I'm defining a NoteCache object that manages the lazy loading. I also add a "state" property to the Note model and Notes collection.
You'll probably want to initialize NoteCache somewhere (probably inside your route) and whenever you want a note or notes, just do this:
var note = noteCache.getNote(5);
var notes = noteCache.getNotes();
Now inside your view, you'll want to listen for state changes in case the note/notes is not loaded yet:
var NoteView = Backbone.View.extend({
initialize: function(){
this.note.state.bind('change', this.render, this);
},
render: function(){
if (this.note.state.get('error') {
// todo: show error message
return this;
}
if (!this.note.state.get('ready') {
// todo: show loader animation
return this;
}
// todo: render view
return this;
}
});
I haven't tested this, so there may be some bugs, but I hope you get the idea.