Develop Reference

Binding a div row to a single item in an observableArray

I'm developing a 3 part upload form, where users can upload 3 sets of files
So far, I've got the following viewModel
var FileGroupViewModel = function (id) {
var self = this;
self.id = ko.observable(id);
self.files = ko.observableArray();
self.removeFile = function (item) {
self.files.remove(item);
}
self.fileUpload = function (data, e) {
var file = e.target.files[0];
self.files.push(file);
};
}
var ViewModel = function () {
var self = this;
self.fileGroups = ko.observableArray();
self.getFileGroupById = function (id) {
ko.utils.arrayFilter(self.fileGroups(), function (item) {
return item.id == id;
});
};
self.uploadFiles = function () {
alert('Uploading');
}
}
var viewModel = new ViewModel();
viewModel.fileGroups.push(new FileGroupViewModel(1));
viewModel.fileGroups.push(new FileGroupViewModel(2));
viewModel.fileGroups.push(new FileGroupViewModel(3));
ko.applyBindings(viewModel);
I have 3 'groups' of files a user can upload to.
(I will do the actual upload functionality later)
I'm struggling with how to bind my row to a specific item of the array?
Maybe I shouldn't use an observable array?
<div class="row files" id="files1" data-bind="???">
<h2>Files 1</h2>
<span class="btn btn-default btn-file">
Browse <input data-bind="event: {change: fileUpload}" type="file" />
</span>
<br />
<div class="fileList" data-bind="foreach: files"> <span data-bind="text: name"></span>
Remove
</div>
</div>
The idea is when a user selects files, they appear in a list under the button:
..with a link to remove the file from the upload queue.
I've set up a fiddle here - https://jsfiddle.net/alexjamesbrown/c9fvzjte/

There are few important modifications required to make your code work independently across files 0,1,2
KeyNote
event: { change: function(){fileUpload($data,$element.files[0])}}
here we are passing our selected file i.e filedata using $element in
change event not in usual click event . Filedata will have complete file information .
view:
<div class="row files" id="files1" data-bind="foreach:fileGroups">
<h2>Files 0</h2>
<span class="btn btn-default btn-file">
Browse <input data-bind="event: { change: function() { fileUpload($data,$element.files[0]) } }" type="file" />
</span>
<div class="fileList" data-bind="foreach: files"> <span data-bind="text: name"></span>
Remove
</div>
viewModel:
var SubFunction = function (data) {
var self = this;
self.name = data.name;
self.removeFile = function (item1) {
item1.files.remove(this); //current reference data & item1 has parent reference data
}
}
var FileGroupViewModel = function (id) {
var self = this;
self.id = ko.observable(id);
self.files = ko.observableArray([new SubFunction({
'name': 'Test'
})]);
self.fileUpload = function (item1, item2) {
self.files.push(new SubFunction(item2));
};
}
var ViewModel = function () {
var self = this;
self.fileGroups = ko.observableArray();
self.getFileGroupById = function (id) {
ko.utils.arrayFilter(self.fileGroups(), function (item) {
return item.id == id;
});
};
self.uploadFiles = function () {
alert('Uploading');
}
}
var viewModel = new ViewModel();
viewModel.fileGroups.push(new FileGroupViewModel(1));
ko.applyBindings(viewModel);
working sample up for grabs here
Working sample if you are planning to reuse your Html

knockout binding handler - undefined bindingContext.$data on IE9

I am trying to create a custom binding handler to apply a role based access to fields on page.
In custom handler it will check values of other observables from viewModel and based on condition it will enable or disable input control.
But I am not able to get current ViewModel through bindingContext.$parent , $root, $data or $rawData.
when I debug on IE it only displays {...}
The issue occurs only on IE, It works fine on google crome.
Can someone help me on how do I get current ViewModel through bindingContext.
var divForm = document.getElementById('divform');
function AuditFormViewModel() {
self = this;
self.Name = ko.observable("Kiran");
self.Email = ko.observable("kiranparab0#gmail.com");
self.Complete = ko.observable(true);
self.Send = ko.observable(false);
self.conditionArray = [
{ Field: "Name", condition: [{ Property: "Complete", Value: true }, { Property: "Send", Value: true }] },
{ Field: "Email", condition: [{ Property: "Complete", Value: false }] }
];
}
ko.bindingHandlers.hasAccess = {
update: function (element, valueAccessor, allBindings, viewModel, bindingContext) {
var field = valueAccessor();
var accessConditions = [];
accessConditions = bindingContext.$data.conditionArray;
var condition = accessConditions.filter(function (cnd) {
return cnd.Field === field
})[0].condition;
var value = true;
for (var i = 0; i < condition.length; i++) {
var cndProp = condition[i].Property;
var cndVal = bindingContext.$data[cndProp]();
value = value && (condition[i].Value === cndVal);
}
ko.bindingHandlers.enable.update(element, function () { return value });
}
};
auditFormViewModel = new AuditFormViewModel();
ko.applyBindings(auditFormViewModel, divForm);
<script src="https://cdnjs.cloudflare.com/ajax/libs/knockout/3.1.0/knockout-min.js"></script>
<div id="divform">
Name : <input type="text" data-bind="value:Name, hasAccess:'Name'" />
<br />
Email : <input type="text" data-bind="value:Email, hasAccess:'Email'" />
</div>
Here is the fiddle

In my code I have not declared self as var,
its just change of line. 'var self = this' instead 'self = this'

knockout unable to process binding "foreach"

I'm new to Knockout and I'm building an app that's effectively a large-scale calculator. So far I have two instances of knockout running on one page. One instance is working perfectly fine, however the other one is entirely broken and just won't seem to register at all?
Below is my Javascript, fetchYear is the function that works perfectly fine and fetchPopulation is the one that's completely broken. It doesn't seem to register "ageview" from the HTML at all and I can't figure out.
The error:
Uncaught ReferenceError: Unable to process binding "foreach: function
(){return ageView }" Message: ageView is not defined
Thanks in advance.
JS:
var index = {
fetchYear: function () {
Item = function(year){
var self = this;
self.year = ko.observable(year || '');
self.chosenYear = ko.observable('');
self.horizon = ko.computed(function(){
if(self.chosenYear() == '' || self.chosenYear().horizon == undefined)
return [];
return self.chosenYear().horizon;
});
};
YearViewModel = function(yeardata) {
var self = this;
self.yearSelect = yeardata;
self.yearView = ko.observableArray([ new Item() ]);
self.add = function(){
self.yearView.push(new Item("New"));
};
};
ko.applyBindings(new YearViewModel(yearData));
},
fetchPopulation: function () {
popItem = function(age){
var self = this;
self.age = ko.observable(age || '');
self.chosenAge = ko.observable('');
self.population = ko.computed(function(){
if(self.chosenAge() == '' || self.chosenAge().population == undefined)
return [];
return self.chosenAge().population;
});
};
PopulationViewModel = function(populationdata) {
var self = this;
self.ageSelect = populationdata;
self.ageView = ko.observableArray([ new popItem() ]);
self.add = function(){
self.ageView.push(new popItem("New"));
};
};
ko.applyBindings(new PopulationViewModel(populationData));
}
}
index.fetchYear();
index.fetchPopulation();
HTML:
<div class="row" data-bind="foreach: yearView">
<div class="grid_6">
<img src="assets/img/index/calendar.png" width="120" height="120" />
<select class="s-year input-setting" data-bind="options: $parent.yearSelect, optionsText: 'year', value: chosenYear"></select>
<label for="s-year">Start year for the model analysis</label>
</div>
<div class="grid_6">
<img src="assets/img/index/clock.png" width="120" height="120" />
<select class="s-horizon input-setting" data-bind="options: horizon, value: horizon"></select>
<label for="s-horizon">Analysis time horizon</label>
</div>
</div>
<div class="row" data-bind="foreach: ageView">
<div class="grid_6">
<img src="assets/img/index/calendar.png" width="120" height="120" />
<select class="s-year input-setting" data-bind="options: ageSelect, optionsText: 'age', value: chosenAge"></select>
<label for="s-agegroup">Age group of <br> target population</label>
</div>
<div class="grid_6">
<img src="assets/img/index/clock.png" width="120" height="120" />
<input class="s-population input-setting"></input>
<label for="s-population">Size of your patient <br> population <strong>National</strong> </label>
</div>
</div>

When you do this (in fetchYear):
ko.applyBindings(new YearViewModel(yearData));
You are binding the entire page with the YearViewModel view model. But the YearViewModel doesn't have a property called ageView so you get the error and knockout stops trying to bind anything else.
What you need to do is restrict your bindings to cover only part of the dom by passing the element you want to ko.applyBindings. For example:
<div class="row" id="yearVM" data-bind="foreach: yearView">
//....
<div class="row" id="popVM" data-bind="foreach: ageView">
And then:
ko.applyBindings(new YearViewModel(yearData), document.getElementById("yearVM"));
//...
ko.applyBindings(new PopulationViewModel(populationData), document.getElementById("popVM"));
Now your bindings are restricted just to the part of the DOM that actually displays stuff from that model.
Another alternative is to just have your two view models as part of a parent view model and then you can apply the binding to the entire page. This makes it easier if you need to mix parts from both VMs and they are not conveniently separated in distinct sections of your page. Something like:
var myParentVM = {
yearVM : index.fetchYear(), // note, make this return the VM instead of binding it
popVM : index.fetchPopulation(), // ditto
}
ko.applyBindings(myParentVM);
And then you'd declare your bindings like so:
<div class="row" data-bind="foreach: yearVM.yearView">

The main reason why this is not working is because you call ko.applyBindings() more than once on a page (that is not really forbidden but is a bad practice in my opinion).
If you need to call it twice, you must call it with a container for which region this bind is meant to.
Something like this:
ko.applyBindings(new YearViewModel(yearData), document.getElementById('YourYearViewElementId'));
The error you get is from the first binding, which tries to process the whole page and does not find the 'ageView' in its ViewModel.
Better would be if you build a single ViewModel for a single Page where you have sub-models for sections if needed.
Some pseudo code for such a scenario:
var Section1ViewModel = function() {
var self = this;
self.property1 = ko.observable();
self.myComputed = ko.computed(function () {
// do some fancy stuff
});
self.myFunc = function() {
// do some more fancy stuff
};
}
var Section2ViewModel = function() {
var self = this;
self.property1 = ko.observable();
self.myComputed = ko.computed(function () {
// do some fancy stuff
});
self.myFunc = function() {
// do some more fancy stuff
};
}
var PageViewModel = function() {
var self = this;
self.section1 = ko.observable(new Section1ViewModel());
self.section2 = ko.observable(new Section2ViewModel());
self.myGlobalFunc = function() {
// do some even more fancy stuff
}
}
ko.applyBindings(new PageViewModel());
Hope that helps.
Best regards,
Chris

knockout.js get parent observable

Is it possible to get parent observable in knockout? Like I have
<div data-bind="parent: {...}">
<div data-bind="child: {...}">
...
</div>
</div>
I want to get access to parent in child but not in the markup but in the code. How can I achieve in a standard knockout way?
UPDATE
I have found a simple way to achieve this by simply accessing the last argument of custom handler like this:
ko.bindingHandlers.custom = {
init: function (element, valueAccessor, allBindingsAccessor, vm, bindingContext) {
console.log(bindingContext.$parent);
}
}

You can use $parent to access the parent item:
<div data-bind="parent: {...}">
<div data-bind="child: {...}">
<span data-bind="text: $parent.someObservable()"></span>
<span data-bind="text: somefunction($parent.someObservable())"></span>
</div>
</div>

The most simple way it to past parent object to child model as a parameter (pointer) when child object constructed. But it more standard javascript way then knockout
var Parent = function (item) {
var self = this;
this.value = ko.observable(item.value);
this.child = new Child(item.child, self);
}
var Child = function (item, parent) {
var self = this;
this.parent = parent;
this.value = ko.observable(item.value);
}
and HTML markup will look like
This is <b><span data-bind="text: value"></span></b>
<div data-bind="with: child">
This is <b><span data-bind="text: value"></span></b>
<br/>
This is <b><span data-bind="text: parent.value"></span></b> of <b><span data-bind="text: value"></span></b>
</div>
JSFIDDLE
To prevent big amount of code mapping plugin could be used and it will be more knockout way
var Parent = function (item) {
var self = this;
var map = {
'child': {
update: function(options) {
return new Child(options.data, self);
}
}
}
ko.mapping.fromJS(item, map, self);
}
var Child = function (item, parent) {
var self = this;
this.parent = parent;
ko.mapping.fromJS(item, null, self);
}
JSFIDDLE
And the most knockout way - it to create custom binding that will controls descendant bindings. In this way you can extend child context with extra properties.
ko.bindingHandlers.withParent = {
init: function(element, valueAccessor, allBindings, viewModel, bindingContext) {
// Make a modified binding context, with a extra properties, and apply it to descendant elements
ko.mapping.fromJS({
parent: bindingContext.$rawData
}, null,valueAccessor());
var childBindingContext = bindingContext.createChildContext(valueAccessor, null, null);
ko.applyBindingsToDescendants(childBindingContext, element);
// Also tell KO *not* to bind the descendants itself, otherwise they will be bound twice
return { controlsDescendantBindings: true };
}
};
Model
var Parent = function (item) {
var self = this;
var map = {
'child': {
update: function(options) {
return new Child(options.data);
}
}
}
ko.mapping.fromJS(item, map, self);
}
var Child = function (item, parent) {
var self = this;
ko.mapping.fromJS(item, null, self);
}
and HTML
This is <b><span data-bind="text: value"></span></b>
<div data-bind="withParent: child">
This is <b><span data-bind="text: value"></span></b>
<br/>
This is <b><span data-bind="text: parent.value"></span></b> of <b><span data-bind="text: value"></span></b>
<br/>
<input type="button" value="Test from code" data-bind="click: test"/>
</div>
JSFIDDLE
But personaly me not like this approach, because using together with 'with', 'foreach' or 'tempalate' bindings it could cause errors like
Message: You cannot apply bindings multiple times to the same element.

Knockout click event visible state

I'm new to Knockout js and I found an issue in button click event. I have a list where each list item has a button for comment. When I click the button, the invisible comment box should be visible. Following is my HTML code:
<ul class="unstyled list" data-bind="foreach: filteredItems">
<li>
<input type="checkbox" value="true" data-bind =" attr: { id: id }" name="checkbox" class="checkbox">
<label class="checkbox-label" data-bind="text: title, attr: { for: id }"></label>
<button class="pull-right icon" data-bind="click: loadComment, attr: { id: 'btn_' + id }"><img src="../../../../../Content/images/pencil.png" /></button>
<div class="description" data-bind="visible: commentVisible, attr: { id : 'item_' + id}">
<textarea data-bind="value: comment" class="input-block-level" rows="1" placeholder="Comment" name="comment"></textarea>
<div class="action">
<button class="accept" data-bind="click: addComment">
<img src="../../../../../Content/images/accept.png" /></button>
<button class="cancel" data-bind="click: cancel">
<img src="../../../../../Content/images/cancel.png" /></button>
</div>
</div>
</li>
</ul>
In my view model, I have mentioned when click the loadComment the comment should be visible
var filteredItems = ko.observableArray([]),
filter = ko.observable(),
items = ko.observableArray([]),
self = this;
self.commentVisible = ko.observable(false);
self.comment = ko.observable();
self.addComment = ko.observable(true);
self.cancel = ko.observable();
self.loadComment = function (item) {
self.commentVisible(true);
}
The problem is when I click the loadComment button, all the comment boxes in each list items getting visible. I want to make only the clicked button's comment box should be appear.
Need some help.
Thanks

You declaration doesnt make much sense to me. commentVisible is not a property of filteredItems so when doing a foreach, it will not be accessible unless you use the $parent binding. FilteredItems itself is a private variable and will not be exposed to the viewmodel and that should cause the binding to fail. I would look at the error console to see if that gives any clues.
Here is what I did to make a somewhat working example (note that this uses parent binding and is probably not what you are going for):
var VM = (function() {
var self = this;
self.filteredItems = ko.observableArray([{id: 1, title: 'Test'}]);
self.filter = ko.observable();
self.items = ko.observableArray([]);
self.commentVisible = ko.observable(false);
self.comment = ko.observable();
self.addComment = ko.observable(true);
self.cancel = function(){
self.commentVisible(false);
};
self.loadComment = function (item) {
self.commentVisible(true);
}
return self;
})();
ko.applyBindings(VM);
http://jsfiddle.net/infiniteloops/z93rN/
Knockout binding contexts: http://knockoutjs.com/documentation/binding-context.html
What you probably want to do it to create a filtered item object with those properties that are referenced within the foreach and populate the filteredItems obeservable array with them.
That might look something like this:
var FilteredItem = function(id,title){
var self = this;
self.id = id;
self.title = title;
self.commentVisible = ko.observable(false);
self.comment = ko.observable();
self.addComment = ko.observable(true);
self.cancel = function(){
self.commentVisible(false);
};
self.loadComment = function (item) {
self.commentVisible(true);
}
}
var VM = (function() {
var self = this;
var item = new FilteredItem(1, 'Test');
self.filteredItems = ko.observableArray([item]);
self.filter = ko.observable();
self.items = ko.observableArray([]);
return self;
})();
ko.applyBindings(VM);
http://jsfiddle.net/infiniteloops/z93rN/2/