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Referencing properties of object constructor outside view model in knockout

So, I'm not entirely sure how to phrase this question as it's sort of two in one. I'm having a weird issue where I have an object constructor to create new 'projects' from an HTML form which are then pushed into an observableArray when the form is submitted. Everything works fine but to reference the related observables I have to use 'value: Project.title' or 'value: Project.whatever'. I haven't seen 'value: NameOfConstructor.property' used in any of the examples I've seen. I assume this works this way because the constructor is outside of my view model.
My question is this: Is there a better way to assign the value of a property in a constructor that is not in my view model? In other words, is there a better or more correct way than 'Project.title', ect?
I ask partially because one thing in my code doesn't work currently; the knockout enable property doesn't work on my "New Project" button, it stays disabled even if there is something written in the 'title' input box. I have the feeling it's because it's written as data-bind='enable: Project.title' but I can't figure how else to write it.
I've included a jsfiddle for reference though it obviously isn't working because of external dependencies.
https://jsfiddle.net/bmLh0vf1/1/
My HTML:
<form id='addBox' action='#' method='post'>
<label for='pTitle'> Title: </label>
<input id='pTitle' data-bind='value: Project.title' />
<br/>
<label for='pPriority'> Priority </label>
<select id='pPriority' data-bind='options: priorityOptions, value: Project.priority'></select>
<br/>
<button data-bind='enable: Project.title, click: newProject'>New Project</button>
</form>
And my Javascript:
function Project(title, priority) {
this.title = ko.observable(title);
this.priority = ko.observable(priority);
};
function ProjectViewModel() {
var self = this;
this.priorityOptions = ko.observableArray(['High', 'Medium', 'Low'])
this.projectList = ko.observableArray([
new Project('Create App', 'High')
]);
this.newProject = function() {
var np = new Project(Project.title, Project.priority);
self.projectList.push(new Project(Project.title, Project.priority));
console.log(self.projectList().length);
if (self.projectList().length > 1) {
console.log(self.projectList()[1].title());
};
}
};
var viewModel = new ProjectViewModel();
$(document).ready(function() {
ko.applyBindings(viewModel);
});
Lastly, I apologize if I've missed any posting conventions or if my code is especially bad. I'm very new and still teaching myself.

Your code is setting title and priority properties on the object created by new Project, but then later you're expecting to see those properties on Project itself. It doesn't have them; Project is the function, not the object created by new Project. So Project.title and Project.priority will give you undefined (and not an observable, and so not useful targets for the value binding).
Instead, have an "editing" Project instance that you use, binding the value of the inputs to the editing' instances title and priority, and then in newProject grab that instance and replace it with a new, fresh one.
Roughly speaking, in ProjectViewModel's constructor:
this.editing = ko.observable(new Project());
Update Project to default title and priority:
function Project(title, priority) {
this.title = ko.observable(title || "");
this.priority = ko.observable(priority || "Medium");
}
And in the bindings:
<input id='pTitle' data-bind='value: editing().title' />
<select id='pPriority' data-bind='options: priorityOptions, value: editing().priority'></select>
And in newProject:
var np = this.editing();
this.editing(new Project());
Then use np (instead of another new Project) when adding to the array.
Here's a simplified example:
function Project(title, priority) {
this.title = ko.observable(title || "");
this.priority = ko.observable(priority || "Medium");
}
function ProjectViewModel() {
var self = this;
this.priorityOptions = ko.observableArray(["High", "Medium", "Low"]);
this.projects = ko.observableArray();
this.editing = ko.observable(new Project());
this.addProject = function() {
this.projects.push(this.editing());
this.editing(new Project());
};
}
ko.applyBindings(new ProjectViewModel(), document.body);
<div>
<div>
<label>
Title:
<input type="text" data-bind="value: editing().title, valueUpdate: 'input'">
</label>
</div>
<div>
<label>
Priority:
<select data-bind='options: priorityOptions, value: editing().priority'></select>
</label>
</div>
<div>
<button type="button" data-bind="click: addProject, enable: editing().title">Add Project</button>
</div>
<hr>
<div>Projects:</div>
<div data-bind="foreach: projects">
<div>
<span data-bind="text: title"></span>
(<span data-bind="text: priority"></span>)
</div>
</div>
</div>
<script src="https://cdnjs.cloudflare.com/ajax/libs/knockout/3.2.0/knockout-min.js"></script>

Splice removing wrong object from ng-repeat in AngularJS

I'm listing an array of names in my view like this:
<div class="checkbox col-md-3" ng-repeat="staff in stafflist | orderBy: 'name'">
<div class="checkboxinner">
<button class="btn btn-staff form-control"
ng-show="!staff.chosen"
ng-click="pushStaff(staff)">
{{staff.name}}
</button> // visible when unselected, invisible when selected
<button class="btn btn-primary form-control"
ng-show="staff.chosen"
ng-click="unpushStaff(staff, $index)">
{{staff.name}}
</button> // visible when selected, invisible when unselected
</div>
</div>
The first button triggers this function, adding the object into the array and being replaced with another button (different color, same content) that is supposed to act as a toggle. This function works perfectly.
$scope.paxlist = [];
$scope.pushStaff = function (staff) {
staff.chosen = true;
$scope.paxlist.push(
{
name: staff.name
}
);
console.log($scope.paxlist);
};
Basically, when I click I add the object, when I click again, I remove it. Here's the remove function:
$scope.unpushStaff = function (staff, $index) {
staff.chosen = false;
var index=$scope.paxlist.indexOf(staff)
$scope.paxlist.splice(index,1);
console.log($scope.paxlist);
}
My problem is that the unpushStaff() will indeed remove an item, but not the item I clicked to remove, but another one.
What am I missing?
Maybe the ng-show is messing with the $index?

Your staff entry in stafflist and the entry in paxlist are not identical. Based on your template below:
<button class="btn btn-staff form-control"
ng-show="!staff.chosen"
ng-click="pushStaff(staff)">
{{staff.name}}
</button> // visible when unselected, invisible when selected
It is clear that each staff entry in stafflist is some sort of object that has at least one attribute name and another chosen.
When you push onto paxlist, you are creating a new object that looks like:
$scope.paxlist.push(
{
name: staff.name
}
);
This is fine. But when you then come to remove it, you are looking for it by:
var index=$scope.paxlist.indexOf(staff)
where staff is the object in stafflist! Of course, that object does not exist in paxlist - a separate object you derived above in paxlist.push() is - and so indexOf() is returning -1, leading splice() to remove the last item on paxlist.

DataPicker not getting binded to textbox ? fiddle provided

Well in other cases i will get datepicker binded to my textbox which will be straight forward but not in this case .
Fiddle link : http://jsfiddle.net/JL26Z/1/ .. while to setup perfect seanrio i tried but unable to bind datepicker to textboxes . except that everything is in place
My code :
**<script id="Customisation" type="text/html">** // here i need to have text/html
<table style="width:1100px;height:40px;" align="center" >
<tr>
<input style="width:125px;height:auto;" class="txtBoxEffectiveDate" type="text" id="txtEffective" data-bind="" />
</tr>
</script>
The above code is used for my dynamic generation of same thing n no of time when i click each time on a button . So above thing is a TEMPLATE sort of thing .
My knockout code :
<div data-bind="template:{name:'Customisation', foreach:CustomisationList},visible:isVisible"></div>
<button data-bind="click:$root.CustomisatioAdd" >add </button>
I tried same old way to bind it with datepicker
$('#txtEffective').datepicker(); // in document.ready i placed
Actually to test this i created a textbox with some id outside script with text/html and binded datepicker to it and It is working fine sadly its not working for the textbox inside text/html and i want to work at any cost.
PS: well i haven't posted my view model as it is not required in this issue based senario
View model added with Js
var paymentsModel = function ()
{
function Customisation()
{
var self = this;
}
var self = this;
self.isVisible = ko.observable(false);
self.CustomisationList = ko.observableArray([new Customisation()]);
self.CustomisationRemove = function () {
self.CustomisationList.remove(this);
};
self.CustomisatioAdd = function () {
if (self.isVisible() === false)
{
self.isVisible(true);
}
else
{
self.CustomisationList.push(new Customisation());
}
};
}
$(document).ready(function()
{
$('#txtEffective').datepicker();
ko.applyBindings(new paymentsModel());
});
Any possible work around is appreciated
Regards

The best way I've found to do this is create a simple bindingHandler.
This is adapted from code I have locally, you may need to tweak it...
** code removed, see below **
Then update your template:
** code removed, see below **
By using a bindingHandler you don't need to try to hook this up later, it's done by knockout when it databinds.
Hope this is helpful.
EDIT
I created a fiddle, because I did indeed need to tweak the date picker binding quite a lot. Here's a link to the Fiddle, and here's the code with some notes. First up, the HTML:
<form id="employeeForm" name="employeeForm" method="POST">
<script id="PhoneTemplate" type="text/html">
<div>
<span>
<label>Country Code:</label>
<input type="text" data-bind="value: countryCode" />
</span>
<span><br/>
<label>Date:</label>
<input type="text" data-bind="datepicker: date" />
</span>
<span>
<label>Phone Number:</label>
<input type="text" data-bind="value: phoneNumber" />
</span>
<input type="button" value="Remove" data-bind="click: $parent.remove" />
</div>
</script>
<div>
<h2>Employee Phone Number</h2>
<div data-bind="template:{name:'PhoneTemplate', foreach:PhoneList}">
</div>
<div>
<input type="button" value="Add Another" data-bind="click: add" />
</div>
</div>
</form>
Note I removed the id=... from in your template; because your template repeats per phone number, and ids must be unique to be meaningful. Also, I removed the datepicker: binding from the country code and phone number elements, and added it only to the date field. Also - the syntax changed to "datepicker: ". If you need to specify date picker options, you would do it like this:
<input type="text" data-bind="datepicker: myObservable, datepickerOptions: { optionName: optionValue }" />
Where optionName and optionValue would come from the jQueryUI documentation for datepicker.
Now for the code and some notes:
// Adapted from this answer:
// https://stackoverflow.com/a/6613255/1634810
ko.bindingHandlers.datepicker = {
init: function(element, valueAccessor, allBindingsAccessor) {
//initialize datepicker with some optional options
var options = allBindingsAccessor().datepickerOptions || {},
observable = valueAccessor(),
$el = $(element);
// Adapted from this answer:
// https://stackoverflow.com/a/8147201/1634810
options.onSelect = function () {
if (ko.isObservable(observable)) {
observable($el.datepicker('getDate'));
}
};
$el.datepicker(options);
// set the initial value
var value = ko.unwrap(valueAccessor());
if (value) {
$el.datepicker("setDate", value);
}
//handle disposal (if KO removes by the template binding)
ko.utils.domNodeDisposal.addDisposeCallback(element, function() {
$el.datepicker("destroy");
});
},
update: function(element, valueAccessor) {
var value = ko.utils.unwrapObservable(valueAccessor()),
$el = $(element);
//handle date data coming via json from Microsoft
if (String(value).indexOf('/Date(') === 0) {
value = new Date(parseInt(value.replace(/\/Date\((.*?)\)\//gi, "$1")));
}
var current = $el.datepicker("getDate");
if (value - current !== 0) {
$el.datepicker("setDate", value);
}
}
};
function Phone() {
var self = this;
self.countryCode = ko.observable('');
self.date = ko.observable('');
self.phoneNumber = ko.observable('');
}
function PhoneViewModel() {
var self = this;
self.PhoneList = ko.observableArray([new Phone()]);
self.remove = function () {
self.PhoneList.remove(this);
};
self.add = function () {
self.PhoneList.push(new Phone());
};
}
var phoneModel = new PhoneViewModel();
ko.applyBindings(phoneModel);
Note the very updated binding handler which was adapted from this answer for the binding, and this answer for handling onSelect.
I also included countryCode, date, and phoneNumber observables inside your Phone() object, and turned your model into a global variable phoneModel. From a debugger window (F12 in Chrome) you can type something like:
phoneModel.PhoneList()[0].date()
This will show you the current value of the date.
I notice that your form is set up to post somewhere. I would recommend instead that you add a click handler to a "Submit" button and post the values from your phoneModel using ajax.
Hope this edit helps.

Dynamic entities need to have datepicker applied after they are created. To do this I'd use an on-click function somewhere along the lines of
HTML
<!-- Note the id added here -->
<button data-bind="click:$root.CustomisatioAdd" id="addForm" >add </button>
<script>
$(document).on('click', '#addForm', function(){
$('[id$="txtEffective"]').datepicker();
});
</script>

Knockout options with forms not binding to model

I am having problems with KnockoutJS and the options binding.
What I'm trying to achieve is functionality to display a form based on selected option with the options binding.
The odd thing is that it works with the first form-field but the model is not value binded for the others.
Here is my markup:
<div id="page">
<form data-bind="submit: executeTask">
<select data-bind="options: availableTasks, value: selectedTask, optionsText: 'description', optionsCaption: 'Select...',"></select>
<div data-bind="visible: selectedTask">
<input type="text" data-bind="value:selectedTask().assignee">
<input type="text" data-bind="value:selectedTask().estimatedTime">
</div>
<button class="btn" type="submit">Submit</button>
</form>
</div>
<script>
$(function() {
var taskController = new TaskController(document.getElementById("page"));
});
</script>
And here is my model:
(function () {
function Task(id, description) {
var model = this;
model.id = ko.observable(id);
model.description = ko.observable(description);
model.assignee = ko.observable();
model.estimatedTime = ko.observable();
};
window.TaskController = function (element) {
var model = this;
model.availableTasks = [
new Task("0", "Laundry"),
new Task("1", "Dinner")];
model.selectedTask = ko.observable();
model.executeTask = function (form) {
console.log(ko.toJSON(model.selectedTask()));
};
ko.applyBindings(this, element);
};
})();
The full code can be found at the following fiddle:
http://jsfiddle.net/LkqTU/17057/
As you can see in the console, only the "assignee" property is getting binded, but not the "estimatedTime" property.
What am I doing wrong?
Thanks,
Bj Blazkowicz

Solution 1:
Replace the visible binding with an if binding:
<div data-bind="visible: selectedTask">
Should be
<div data-bind="if: selectedTask">
Explanation
You were getting an error because it could not find selectedTask().assignee. The problem was that selectedTask() returned undefined at page load. Even though the inputs were not visible due to visible: selectedTask, the binding was interpreted.
With the if binding, what is inside the tag is ignored when selectedTask() returns undefined.
Solution 2:
As nemesv pointed out, you can use the with binding (see his answer):
<div data-bind="with: selectedTask">
<input type="text" data-bind="value: assignee">
<input type="text" data-bind="value: estimatedTime">
</div>

How to create an observable array with undo?

I am trying to add knockout JS to a search page on our website. Currently you open up a jQuery dialog box, which has a number of checkboxes of criteria that you can select.
There are multiple dialogs with multiple types of criteria. When you open the dialog, the checkboxes do not take effect until you hit an "Update" button, if you click cancel or just close the window, the changes you made get reverted and the dialog is set to its former state.
I read this and a few other posts. However this seems to only work with ko.observable, and I cannot seem to get it to work with ko.observableArray.
Has anyone accomplished this or have any ideas?
An example of what I want to do:
Html:
<form>
<div>
<div>
<label><input type="checkbox" data-bind="checked: genders" value="1" />Male</label>
<label><input type="checkbox" data-bind="checked: genders" value="2" />Female</label>
</div>
</div>
<a id="buttonCancel">Cancel</a>
<a id="buttonUpdate">Update</a>
</form>
<div data-bind="text: ko.toJSON(viewModel)"></div>
Javascript:
var viewModel = {
genders: ko.observableArrayWithUndo([])
};
ko.applyBindings(viewModel);
$('#buttonCancel').click(function(){
viewModel.genders.resetChange();
});
$('#buttonUpdate').click(function(){
viewModel.genders.commit();
return false;
});

Here would be one way to approach it:
//wrapper to an observableArray of primitive types that has commit/reset
ko.observableArrayWithUndo = function(initialArray) {
var _tempValue = ko.observableArray(initialArray.slice(0)),
result = ko.observableArray(initialArray);
//expose temp value for binding
result.temp = _tempValue;
//commit temp value
result.commit = function() {
result(_tempValue.slice(0));
};
//reset temp value
result.reset = function() {
_tempValue(result.slice(0));
};
return result;
};
You would bind your checkboxes to yourName.temp and the other part of your UI to just yourName.
Here is a sample: http://jsfiddle.net/rniemeyer/YrfyW/
The slice(0) is one way to get a shallow copy of an array (or even just slice()). Otherwise, you would be performing operations on a reference to the same array.

Given HTML similar to:
<div>
<button data-bind="click: function() { undo(); }">Undo</button>
<input data-bind="value: firstName" />
<input data-bind="value: lastName" />
<textarea data-bind="value: text"></textarea>
</div>
You could use some Knockout code similar to this, basically saving the undo stack as a JSON string representation of the state after every change. Basically you create a fake dependent observable to subscribe to all the properties in the view, alternatively you could manually iterate and subscribe to each property.
//current state would probably come from the server, hard coded here for example
var currentState = JSON.stringify({
firstName: 'Paul',
lastName: 'Tyng',
text: 'Text'
})
, undoStack = [] //this represents all the previous states of the data in JSON format
, performingUndo = false //flag indicating in the middle of an undo, to skip pushing to undoStack when resetting properties
, viewModel = ko.mapping.fromJSON(currentState); //enriching of state with observables
//this creates a dependent observable subscribed to all observables
//in the view (toJS is just a shorthand to traverse all the properties)
//the dependent observable is then subscribed to for pushing state history
ko.dependentObservable(function() {
ko.toJS(viewModel); //subscribe to all properties
}, viewModel).subscribe(function() {
if(!performingUndo) {
undoStack.push(currentState);
currentState = ko.mapping.toJSON(viewModel);
}
});
//pops state history from undoStack, if its the first entry, just retrieve it
window.undo = function() {
performingUndo = true;
if(undoStack.length > 1)
{
currentState = undoStack.pop();
ko.mapping.fromJSON(currentState, {}, viewModel);
}
else {
currentState = undoStack[0];
ko.mapping.fromJSON(undoStack[0], {}, viewModel);
}
performingUndo = false;
};
ko.applyBindings(viewModel);
I have a sample of N-Level undo with knockout here:
http://jsfiddle.net/paultyng/TmvCs/22/
You may be able to adapt for your uses.