Develop Reference

KnockoutJS - foreach not working with a single entry in viewmodel

I have the following code that, on a successful AJAX return, displays a popup window with a list of addresses. The knockout version is 2.3.0.
If there is more than 1 address then the html correctly renders with a 'display' string.
The problem is that if there is ONLY 1 address the html list renders but without any text in the span.
In both cases the view model is correctly being populated with data so it looks to me like a problem updating the html.
I have tried pushing the data again and although I can use jQuery to update the html but this doesn't help me understand the problem.
HTML
<div id="reverseGeocodingResults">
<div class="modal-content">
<div class="modal-header">
<h4 class="modal-title">Local Addresses</h4>
</div>
<div>
<ul data-bind="foreach: vm.reverseGeocodingViewModel.AddressList" class="locationList">
<li class="locationListItem" data-bind="click: SubmitAddressRequest">
<div>
<span data-bind="text: Display"></span>
</div>
</li>
</ul>
</div>
</div>
</div>
Javascript (from a separate file so only taken what I think is relevant)
var vm;
var masterViewModel = function () {
this.viewModel = { LocationList: ko.observableArray([]), SubQuery: ko.observable() };
this.reverseGeocodingViewModel = { AddressList: ko.observableArray([]) };
};
function SubmitReverseGeocodingRequest(easting, northing, projectId, mouseLocation) {
$.post('url?action=ReverseGeocodingLookup', {
easting: easting,
northing: northing,
pid: projectId
})
.done(function (data) {
spinner.stop();
if (parseInt(data.NumberOfAddressesFound) > 0) {
if (data.AddressList.length == 1) {
alert('just 1 address');
}
// remove all array items before adding new
// Not pretty but gets around an issue the UI seems to have displaying the updated list
if (vm.reverseGeocodingViewModel.AddressList().length > 0) {
vm.reverseGeocodingViewModel.AddressList.splice(0, vm.reverseGeocodingViewModel.AddressList().length);
}
vm.reverseGeocodingViewModel.AddressList(data.AddressList);
}
});
)
$(document).ready(function () {
vm = new masterViewModel();
ko.applyBindings(vm);
})
HTML Result - Multiple Results
<ul class="locationList" data-bind="foreach: vm.reverseGeocodingViewModel.AddressList" style="height: 265px;">
<li data-bind="click: SubmitAddressRequest" class="locationListItem">
<div>
<span data-bind="text: Display">Yates Wine Lodge, SWINDON</span>
</div>
</li>
<li data-bind="click: SubmitAddressRequest" class="locationListItem">
<div>
<span data-bind="text: Display">The Brunel Centre, SWINDON</span>
</div>
</li>
</ul>
HTML Result - Single Result
<ul class="locationList" data-bind="foreach: vm.reverseGeocodingViewModel.AddressList" style="height: 265px;">
<li class="locationListItem" data-bind="click: SubmitAddressRequest">
<div>
<span data-bind="text: Display"></span>
</div>
</li>
</ul>
I have looked at various previous questions on this topic and couldn't come up with an answer hence the question, but please point me to another post if I have missed one.

to remove all before add new use reverseGeocodingViewModel.AddressList.removeAll()
Maybe didn't find it but you have to parse data, $.parseJSON I use for this.
Try to use
$.each($.parsejSON(data), function(i, el){
reverseGeocodingViewModel.AddressList.push(el);
})
I hope it will help you

I've noticed following issues:
function SubmitReverseGeocodingRequest should be closed with } not )
foreach: vm.reverseGeocodingViewModel.AddressList should be foreach: reverseGeocodingViewModel.AddressList, without vm because vm is already binded
vm = new masterViewModel();
ko.applyBindings(vm);
To clean AddressList use vm.reverseGeocodingViewModel.AddressList([]) instead vm.reverseGeocodingViewModel.AddressList.splice(0, vm.reverseGeocodingViewModel.AddressList().length);
Note: Here's possible mistake
<li class="locationListItem" data-bind="click: SubmitAddressRequest">
so AddressList item have to have the SubmitAddressRequest function. I don't think that you get data with the function
I've created test sample based on your code, take a look here

How can a data-bind to an element within a Kendo-Knockout listview?

I have a rather sophisticated template for Kendo ListView using knockout-kendo.js bindings. It displays beautifully. My problem is that I need to use the visible and click bindings in parts of the template, but I can't get them to work. Below is a simplified version of my template. Basically, deleteButtonVisible determines whether the close button can be seen, and removeComp removes the item from the array.
<div class='template'>
<div >
<div style='display:inline-block' data-bind='visible: deleteButtonVisible, event: {click: $parent.removeComp}'>
<img src='../../../Img/dialog_close.png'></img>
</div>
<div class='embolden'>#= type#</div><div class='label1'> #= marketArea# </div>
<div class='label2'> #= address# </div>
<!-- more of the same -->
</div>
The view model:
function CompViewModel() {
var self = this;
self.compData = ko.observableArray().subscribeTo("compData");
self.template = kendo.template(//template in here);
self.removeComp = function (comp) {
//do something here
}
}
html:
<div class="row" >
<div class="col-md-12 centerouter" id="compDiv" >
<div class="centerinner" id="compListView" data-bind="kendoListView: {data: compData, template: template}"></div>
</div>
</div>
finally, sample data:
{
type: "Comparable",
marketArea: "",
address: "2327 Bristol St",
deleteButtonVisible: true
},

Take in count that the deleteButtonVisible must be a property on the viewModel linked to the view.You are not doing that right now. The click element can v¡be access from the outer scope of the binding and remove the $parent.He take the method from the viewmodel. Take in count that every thing that you take on the vie must be present on the view model for a easy access.

How can I apply KnockoutJS on a master page and an individual page?

I'm stuck on an older WebForms project and I'd like to know if there's a recommended approach for my scenario.
Goal
I have a feedback form in a modal dialog that I bound up using KnockoutJS.
I would like the feedback form to be available on all pages, via a link in the footer of the site.
I would like to have several other pages using knockout as well with their own individual scripts & bindings, irrespective of the feedback form bindings in the modal.
I have some pages that do not use knockout at all. I would like them not to have to insert code to accomplish this.
I would like to avoid global variables, if possible, in favor of namespaced JavaScript.
In essence, I would like for the viewmodels on the page and the feedback viewmodel not to be aware of each others' existence.
Current Setup
Our footer links are in a Site.master file, and so that's where I've placed the Feedback.js script and the div for the modal which has the bindings. So on the master page, I call ko.applyBindings(vm, referenceToFeedbackDiv), which works fine to wire up the feedback form.
Our individual pages occasionally have a knockout viewmodel, and so they may call ko.applyBindings(vm), since to their knowledge they'd like to apply the vm to their entire page.
Problem
This causes a conflict in knockout because one vm is being applied to the feedback form via the Site.master call, and one vm is being applied to the entire body by the page after it.
Question
How can I enable these two things -- a modal dialog across all pages that uses knockout, and individual knockout pages -- to work in harmony?
Demonstration of the Issue in (the Current) Code
Remember, the issue is that I want to be able to have one feedback VM that applies only to the feedback div across the client site, and I want to have other VMs able to be applied that aren't required to know anything about the feedback vm.
Master Page file (Site.Master) -- Excerpt
This is on every page:
<div class="page">
<div class="main">
<asp:ContentPlaceHolder ID="MainContent" runat="server" />
</div>
</div>
<div class="footer">
© <%=DateTime.Now.Year.ToString() %> Company, Inc. | Home | About |
<!-- begin feedback area -->
<span id="FeedbackArea">
<a data-bind="click: showModal">Feedback</a>
<div id="feedback-modal" title="What's on your mind?">
<div class="btn-group" id="feedbackButtonGroup">
<button class="btn" data-bind="click: UpdateFeedbackType" style="padding-top: 6px;">
<i class="fa fa-warning fa-2x fa-align-center"></i>
<br />
<span>Problem</span>
</button>
<button class="btn" data-bind="click: UpdateFeedbackType" style="padding-top: 6px;">
<i class="fa fa-question-circle fa-2x fa-align-center"></i>
<br />
<span>Question</span>
</button>
<button class="btn" data-bind="click: UpdateFeedbackType" style="padding-top: 6px;">
<i class="fa fa-lightbulb-o fa-2x fa-align-center"></i>
<br />
<span>Suggestion</span>
</button>
<button class="btn" data-bind="click: UpdateFeedbackType" style="padding-top: 6px;">
<i class="fa fa-thumbs-o-up fa-2x fa-align-center"></i>
<br />
<span>Praise</span>
</button>
<button class="btn" data-bind="click: UpdateFeedbackType" style="padding-top: 6px;">
<i class="fa fa-info-circle fa-2x fa-align-center"></i>
<br />
<span>General</span>
</button>
</div>
<br />
<br />
<textarea rows="5" placeholder="Enter feedback here" data-bind="value: feedbackText, valueUpdate: 'afterkeydown'"></textarea>
<br />
<br />
<button>Send Feedback</button>
<button data-bind="click: CancelFeedback">Cancel</button>
<h3>Other Information: </h3>
<ul>
<li><strong>Feedback Type:</strong> <span data-bind="text: feedbackType"></span></li>
<li><strong>Current URL:</strong> <span data-bind="text: pageUserIsOn"></span></li>
<li><strong>Current User: </strong><%=hdnLoggedInUsername.Value %></li>
<li><strong>Current Client: </strong>[Not yet captured]</li>
<li><strong>Current Tab: </strong>[Not yet captured]</li>
</ul>
</div>
</span>
<!-- End feedback area -->
</div>
Feedback.JS -- This is also included in every page
...a somewhat-namespaced definition of a FeedbackVM:
var FeedbackNamespace = FeedbackNamespace || {};
..the definition of the namespace itself:
FeedbackNamespace = {
ViewModel: function () {
// etc. etc.
}
};
...and the declaration of a VM variable plus wiring it up on document.ready():
var FeedbackVM;
$(document).ready(function () {
FeedbackVM = new FeedbackNamespace.ViewModel();
ko.applyBindings(FeedbackVM, $('#FeedbackArea')[0]);
FeedbackVM.Start();
log('FeedbackVM started');
});
Other Pages without Knockout / JS
Other pages may or may not have any javascript on them at all, let alone knockout. On these pages, the FeedbackVM currently works fine.
Pages with their own Knockout ViewModel
These pages would have their own namespaced JS file with their own document.ready() event, that creates a vm of say invoiceUploaderVM = new InvoiceUploader.ViewModel(), and then calls ko.applyBindings(invoiceUploaderVM).
This is where we run into trouble.
Update: One potential Approach and a little trouble
In the Site.master page, I wrapped my entire footer in a "stopBindings: true" div:
<div data-bind="stopBindings: true">
<div class="footer" id="footerDiv">
<!-- Feedback Viewmodel stuff in here -->
</div>
</div>
I've defined stopBindings as:
ko.bindingHandlers.stopBindings = {
init: function () {
return { controlsDescendantBindings: true };
}
};
My Feedback.js file, loaded on every page as part of a global JS file, has:
var FeedbackNamespace = FeedbackNamespace || {};
FeedbackNamespace = {
// defines viewmodel, etc. etc.
};
var FeedbackVM;
$(document).ready(function () {
FeedbackVM = new FeedbackNamespace.ViewModel();
ko.applyBindings(FeedbackVM, $('#footerDiv')[0]);
FeedbackVM.Start();
log('FeedbackVM started');
});
This approach works perfectly well -- as long as there are no other viewmodels being bound. On the pages that inherit from my master page, I might have something like:
$(document).ready(function () {
'use strict';
vm = new invoiceUploader.ViewModel();
ko.applyBindings(vm);
});
I would expect that this:
Sets up the feedback viewmodel applied to the div, stopping other viewmodels
Sets up the invoiceUploader viewmodel and applies it to the body (which is then stopped by the stopBindings div)
However, instead I get an error upon loading the child page along the lines of:
Commenting the line to apply the feedback bindings makes this work just fine again.
What am I doing wrong?

I think I would put the view model for your modal in a global object and do whatever you need to do with it aside from applying the bindings in a shared script:
window.feedbackModal = {
foo: ko.observable("Whatever you need to do here"),
bar: ko.observable("assuming it can be done the same on every page")
};
Then in the Site.master
<div class="feedback-modal" data-bind="with: feedbackModal">
<p data-bind="text: foo"></p>
<p data-bind="text: bar"></p>
</div>
And in every individual page's script:
function ViewModel() {
this.individualProperty = ko.observable(true);
this.specificAction = function() { /* do something specific to this page */ };
this.feedbackModal = window.feedbackModal;
}
ko.applyBindings(new ViewModel());
So window.feedbackModal could be undefined and it won't cause you problems, but if you ko.applyBindings, you have to have a feedbackModal property exposed in the view model or you'll get errors applying those bindings.
Of course, there are more clever ways you could implement this basic idea in order to fit your patterns the best, but the big point is, as you know, you can't apply bindings twice, so you need to defer that task to your most specific code and expose your reusable code to to it.

Here is another strategy for separation of common modules from page dependant modules:
// An example of a module that runs on everypage
var modalDialog = function(){
this.name = "dialog1";
this.title = ko.observable("My Modal Title");
this.content = ko.observable("My Modal content is also something");
}
// An example of a module that runs on everypage
var modalDialog2 = function(){
this.name = "dialog2";
this.title = ko.observable("My Modal Title 2");
this.content = ko.observable("My Modal content is also something 2");
}
// Either generate it automatically or by hand
// to represent which modules are common
var commonModules = [modalDialog, modalDialog2];
// An example of a module only for this page
var pageModule = function(){
this.pageFunction = function(){
alert("Called page function");
}
}
// Composition is the final object you will actually bind to the page
var composition = {
pageMod: new pageModule()
}
// Let's add the common modules to the composition
ko.utils.arrayForEach(commonModules, function(item){
var module = new item();
composition[module.name] = module;
});
// Bind the composition
ko.applyBindings(composition);
example HTML for this would be:
<div class="modalDialog">
<h2 data-bind="text: dialog1.title"><h2>
<h2 data-bind="text: dialog1.content"><h2>
</div>
<div class="modalDialog">
<h2 data-bind="text: dialog2.title"><h2>
<h2 data-bind="text: dialog2.content"><h2>
</div>
<div id="content">
<h2>Welcome to page</h2>
<div id="somePageStuff">
Click me
</div>
</div>
Link to the jsfille for this

You can set this up by using a technique to not have scope your bindings to a specific area in your page.
Check out: How to stop knockout.js bindings evaluating on child elements
Example:
http://jsfiddle.net/anAgent/RfM2R/
HTML
<div id="Main">
<label data-bind="text: ViewModel.Name">default</label>
<div data-bind="stopBindings: true">
<div id="ChildBinding">
<label data-bind="text: AnotherViewModel.Name">default</label>
</div>
</div>
</div>
JavaScript
$(function () {
ko.bindingHandlers.stopBindings = {
init: function () {
return {
controlsDescendantBindings: true
};
}
};
var data = {
ViewModel: {
Name: "Testing"
}
};
var data2 = {
AnotherViewModel: {
Name: "More Testing"
}
};
ko.applyBindings(data, $("#Main")[0]);
ko.applyBindings(data2, $("#MyModalHtml")[0]);
});

Running click functions on every instance of listing instead of current

I have a listing of articles here, and I can't figure out how to execute the ng-click function calls on every new article inside the ng-repeat. Right now it works for existing articles, but when new articles are added dynamically (via AJAX), I need those to have the same functionality too.
For example: the ng-click function calls on the "+" sign to reveal social buttons seem to not work once new articles are inserted via AJAX (ie: delete articles, and let list be populated again with new elements)
Does AngularJS provide any tools to do that?
<div>
<div>
<input type="text" ng-model="search">
<span>{{filtered.length}} article(s)</span>
</div>
<div article-listing ng-repeat="article in filtered = (wikiArticles | filter:search)">
<!--Individual article begin-->
<span>
{{article.title}}
</span>
<div>
<a ng-click="articles.removeArticle($index)" title="Delete">
<span>✖</span>
</a>
<a ng-click="articles.toggleShare(article)">
<span class="plus-sign" title="Share">✖</span>
<div social-share ng-show="article.socialShare">
<div ng-click="socialShare = !socialShare" class="addthis_toolbox addthis_default_style addthis_32x32_style"
addthis:title="{{article.title}}" addthis:description="{{article.extract}}" addthis:url="{{article.url}}">
<a class="addthis_button_facebook"></a>
<a class="addthis_button_twitter"></a>
<a class="addthis_button_google_plusone_share"></a>
<a class="addthis_button_reddit"></a>
<a class="addthis_button_hackernews"></a>
</div>
</div>
</a>
</div>
<div>{{article.extract}}</div>
<!--Individual article end-->
</div>
</div>
Code for ng-click calls that don't seem to work for new article insertions
$scope.articles = (function() {
return {
shuffleArticles : function() {
$scope.wikiArticles.reverse();
},
removeArticle : function(index) {
$scope.wikiArticles.splice(index, 1);
$scope.fireAPICalls();
},
toggleShare : function(currArticle) {
var previousState = currArticle.socialShare;
angular.forEach($scope.wikiArticles, function(article) {
article.socialShare = false;
});
currArticle.socialShare = previousState ? false : true;
}
}
})();

Your ng-click calls are actually working- you can watch the ng-show toggle in the debugger.
The problem is that there is nothing to display on the new items you add.
The articles you initially add all have their icons populated with the .addthis classes, for instance here's your Facebook icon element:
<a class="addthis_button_facebook at300b" title="Facebook" href="#">
<span class=" at300bs at15nc at15t_facebook">
<span class="at_a11y">Share on facebook</span>
</span>
</a>
at300bs includes the following css which displays the image:
background: url(widget058_32x32.gif) no-repeat left!important;
However as you add new items, you aren't including the needed .addthis classes to them. Their elements look like this:
<a class="addthis_button_facebook"></a>
So ng-show has nothing to display (it shows a 0x0 div).
Add the .addthis classes to your new elements as you add them and you'll be all set.

Knockout.js mapping. How to update only part of view model?

I want to build simple page where user can select one photo from list and modify some properties, so i had built the model:
model = {
newPhotos: [],
currentPhoto: {
id: 0,
description: ""
},
setCurrent: function (photo, e) {
ko.mapping.fromJS(ko.mapping.toJS(photo), viewModel.currentPhoto);
}
}
and markup:
<div class="content" data-bind="foreach: newPhotos">
<div class="photo" data-bind="click: $parent.setCurrent">
<div class="frame" data-bind="img: imageSrc">
</div>
</div>
</div>
<div class="edit-area" data-bind="with: currentPhoto">
<canvas id="image-edit" />
<textarea class="multi-line" name="PhotoDesc" data-bind="value: description"></textarea>
</div>
Main idea is that when user click on photo, setCurrent function called and there i can update currentPhoto with view model that click binding pass into setCurrent, but there is problem ko.mapping.fromJS(jsObj, viewModel) (as i can see from source) expecting that viewModel will be root model.
I know that i can manually go through all observables and refresh their values, or unmap rootModel, set property and then update root, but i belive that there is more complex and elegant way to do this.
Thank you.

Set up your current photo as an observable, and then you can use map to load the observable with JSON details.
self.currentPhoto(ko.mapping.fromJS(data));
Here's a working JSFiddle to demonstrate:
http://jsfiddle.net/jearles/wgZ59/7/