Develop Reference

Uncaught TypeError: Unable to process binding "if" with knockout

I am simply trying to create some checkboxes and inputs that get the data from database and saving it back to database after edit. But I am getting the following error:
Uncaught TypeError: Unable to process binding "if: function(){return $root.editAlarmValues }"
Message: Unable to process binding "enable: function(){return $root.editAlarmValues().setAlarmValues() }"
Message: $root.editAlarmValues(...).setAlarmValues is not a function
I am not sure what I am doing wrong. I checked in the console and the values get mapped correctly to the array but they don't seem to bind to view. Any help will be highly appreciated!
Here is the code:
<!--ko if: $root.editAlarmValues -->
<div class="row">
<div class="col-md-6">
<input type="checkbox" data-bind="iCheck: $root.editAlarmValues().setAlarmValues" class="large-check"/>
</div>
</div>
<div class="row">
<div class="col-md-5 form-inline">
<input type="checkbox" data-bind="iCheck: $root.editAlarmValues().setOutputCurrentPPLowValue, enable: $root.editAlarmValues().setAlarmValues()" class="large-check"/>
<input type="text" id="OutputCurrentPPLowValue" data-bind="value: $root.editAlarmValues().outputCurrentPPLowValue, enable: $root.editAlarmValues().setOutputCurrentPPLowValue()" class="form-control" maxlength="30" />
</div>
</div>
<div class="row">
<div class="col-md-12">
<div class="pull-right">
<button type="button" class="btn btn-primary btn-flat" data-bind="event: {click: $root.editSave}">Save</button>
</div>
</div>
</div>
<!-- /ko -->
and script:
var AlarmsViewModel = function (wellID) {
function EditAlarms(setAlarmValues, setOutputCurrentPPLowValue, outputCurrentPPLowValue) {
var self = this;
self.setAlarmValues = ko.observable(setAlarmValues);
self.setOutputCurrentPPLowValue = ko.observable(setOutputCurrentPPLowValue);
self.outputCurrentPPLowValue = ko.observable(outputCurrentPPLowValue);
}
var self = this;
self.wellID = ko.observable(wellID);
self.editAlarmValues = ko.observableArray();
self.init = function () {
self.editAlarmInit();
};
self.editAlarmInit = function () {
APIHelper.getData("/api/alarmapi/EditAlarms?wellID=" + self.wellID(), self.editAlarmsCallback, "");
};
self.editAlarmsCallback = function (data) {
//Map results
var temp = $.map(data.result, function (item) {
return new EditAlarms(item.setAlarmValues, item.setOutputCurrentPPLowValue, item.outputCurrentPPLowValue);
});
self.editAlarmValues(temp);
};
self.editSave = function () {
var jsonData = ko.toJSON(self.editAlarmValues);
APIHelper.postData("/api/alarmapi/EditAlarmsPost", jsonData);
};
self.init();
};
var wellID = #ViewBag.WellID;
ko.bindingHandlers.iCheck = {
init: function (el, valueAccessor) {
var observable = valueAccessor();
$(el).on("ifChanged", function () {
observable(this.checked);
});
},
update: function (el, valueAccessor) {
var val = ko.utils.unwrapObservable(valueAccessor());
if (val) {
$(el).iCheck('check');
} else {
$(el).iCheck('uncheck');
}
}
};
var vm = new AlarmsViewModel(wellID);
ko.applyBindings(vm);

You don't want a <!-- ko if: editAlarmValues -->, you want a <!-- ko foreach: editAlarmValues -->. The foreach will not run when the target array is empty, so it fundamentally fulfills the same function.
Inside the foreach, the binding context is the EditAlarms object in question, so you should refer to its properties directly (iCheck: setOutputCurrentPPLowValue instead of iCheck: $root.editAlarmValues().setOutputCurrentPPLowValue).
Also think about your naming. EditAlarms is not a good name for a single object. The prefix set... should refer to a method that sets something. In this case it's just an observable property. setAlarmValues should be called alarmValues, and because it's not an array, it probably should actually be called alarmValue. And so on.
<!-- ko foreach: editAlarmValues -->
<div class="row">
<div class="col-md-6">
<input type="checkbox" data-bind="iCheck: setAlarmValues" class="large-check">
</div>
</div>
<div class="row">
<div class="col-md-5 form-inline">
<input type="checkbox" class="large-check" data-bind="
iCheck: setOutputCurrentPPLowValue,
enable: setAlarmValues
">
<input type="text" id="OutputCurrentPPLowValue" class="form-control" maxlength="30" data-bind="
value: outputCurrentPPLowValue,
enable: setOutputCurrentPPLowValue
">
</div>
</div>
<div class="row">
<div class="col-md-12">
<div class="pull-right">
<button type="button" class="btn btn-primary btn-flat" data-bind="click: $root.editSave">Save</button>
</div>
</div>
</div>
<!-- /ko -->
Revised JS code (move the binding handler definitions to the top, don't nest viewmodels)
ko.bindingHandlers.iCheck = {
init: function (el, valueAccessor) {
var observable = valueAccessor();
$(el).on("ifChanged", function () {
observable(this.checked);
});
},
update: function (el, valueAccessor) {
var val = ko.unwap(valueAccessor());
$(el).iCheck(val ? 'check' : 'uncheck');
}
};
function EditAlarms(setAlarmValues, setOutputCurrentPPLowValue, outputCurrentPPLowValue) {
this.setAlarmValues = ko.observable(setAlarmValues);
this.setOutputCurrentPPLowValue = ko.observable(setOutputCurrentPPLowValue);
this.outputCurrentPPLowValue = ko.observable(outputCurrentPPLowValue);
}
function AlarmsViewModel(wellID) {
var self = this;
self.wellID = ko.observable(wellID);
self.editAlarmValues = ko.observableArray();
self.editAlarmInit = function () {
APIHelper.getData("/api/alarmapi/EditAlarms?wellID=" + self.wellID(), function (data) {
var alarms = data.result.map(item => new EditAlarms(
item.setAlarmValues,
item.setOutputCurrentPPLowValue,
item.outputCurrentPPLowValue
));
self.editAlarmValues(alarms);
});
};
self.editSave = function () {
APIHelper.postData("/api/alarmapi/EditAlarmsPost", ko.toJSON(self.editAlarmValues));
};
self.editAlarmInit();
}
var vm = new AlarmsViewModel(#ViewBag.WellID);
ko.applyBindings(vm);

Javascript, The <p> element displays [object HTMLInputElement] why does it display this?

I am trying to figure out Object Oriented Programming in javascript and instead of displaying the input on form it displays [object HTMLInputElement]
document.getElementById('submit').addEventListener('click', function() {
let uName = document.getElementById('uName').value;
info.showInfo();
});
class Information {
constructor(name) {
this.name = name;
}
showInfo() {
var z = document.createElement('p');
z.innerHTML = this.name;
document.body.appendChild(z);
}
}
const info = new Information(uName);
<form action="/home.php" method="get"></form>
<label for="fname">First name:</label>
<input type="text" name="name" id="uName" value="value" />
<button id="submit">Submit</button>

As #Teemu said in comment let uName is invisible for const info = new Information(uName);
Try following code.
uNameElement = document.getElementById('uName');
document.getElementById('submit').addEventListener('click', function() {
const info = new Information(uNameElement.value);
info.showInfo();
});
class Information {
constructor(name) {
this.name = name;
}
showInfo() {
var z = document.createElement('p');
z.textContent = this.name;
document.body.appendChild(z);
}
}
<form action="/home.php" method="get"></form>
<label for="fname">First name:</label>
<input type="text" name="name" id="uName" value="value" />
<button id="submit">Submit</button>
UPDATE: z.innerHTML replaced by z.textContent

Sending only the updated object from ko.observableArray

How can I send only the updated model from an observable Array instead of sending the entire array?
var student = function (){
this.studentId=0;
this.firstName=ko.obserable();
this.lastName=ko.obserable();
}
var course= function (){
this.courseId=0;
this.students=ko.obserableArray([]);
this.Name=ko.obserable();
}
Now I want to get only that particular student from course whose info is updated. Assuming that when we add a new class we can dynamically add new students to it on the go. Supposing that you have to validate the previous student before adding a new one. When I get that particular student I want to send that student info back to the server.
Thanks.

If I understood your task right, you could use "arrayChange" event type to get exact changed (added/removed) items:
sourceArray = ko.observableArray();
sourceArray.subscribe(function (changes) {
changes.forEach(function(arrayChange) {
if(arrayChange.status === 'added') {
// some code on add
} else if(arrayChange.status === 'deleted') {
// some code on delete
}
});
}, null, "arrayChange");

If you want to get list of students which have been modified, you can provide a flag to identify if an object has been modified in student object. Use .subscribe to modify that flag whenever a value is updated. Then use ko.computed or ko.pureComputed to get that list.
Also it supposes to be observable.
var student = function (id, firstName, lastName) {
var self = this;
self.hasChanged = ko.observable(false);
var modified = function(){
self.hasChanged(true);
};
self.studentId = ko.observable(id);
self.firstName = ko.observable(firstName);
self.firstName.subscribe(modified);
self.lastName = ko.observable(lastName);
self.lastName.subscribe(modified);
}
var course= function (){
var self = this;
self.courseId = 0;
self.students = ko.observableArray([new student(1, "Cristiano", "Ronaldo"), new student(2, "Lionel", "Messi")]);
self.modifiedStudent = ko.computed(function(){
return ko.utils.arrayFilter(self.students(), function(student) {
return student.hasChanged();
});
}, self);
self.Name = ko.observable("Programming 101");
}
$(document).ready(function () {
var myViewModel = new course();
ko.applyBindings(myViewModel);
});
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/knockout/3.2.0/knockout-min.js"></script>
List of all students:
<div data-bind="foreach: students">
<div>
<span data-bind="text: studentId"></span>
<input type="text" data-bind="value: firstName" />
<input type="text" data-bind="value: lastName" />
</div>
</div>
<br/>
List of students which has been modified:
<div data-bind="foreach: modifiedStudent">
<div>
<span data-bind="text: studentId"></span>
<input type="text" data-bind="value: firstName" readonly />
<input type="text" data-bind="value: lastName" readonly />
</div>
</div>

Knockout : find out which observable triggerred computed

I have an object with multiple observables. Is there a way in a computed to know which observable changes, therefore which observable fired the computed?
Thank you in advance
Matthew

Without details of exactly what you are trying to achieve, I'll post this in the hope it might help.
A simple way to track changes is to use the .subscribe method on an observable you want to track. Each time the observable gets updated, this method will fire.
self.myValue = ko.observable('initial value');
self.myValue.subscribe(function (item) {
alert('myValue has changed to: ' + item);
});
The item passed in to the subscribe function is optional, so you can use the new value if required.
Here's a simple example of it in use with a computed:
Sample JSFiddle
JS:
var viewModel = function () {
var self = this;
self.firstName = ko.observable('Mod');
self.lastName = ko.observable('dinu');
self.valueChanged = ko.observable('');
self.fullName = ko.computed(function () {
var val = '';
if (self.valueChanged() !== '') {
val = ' (' + self.valueChanged() + ' Changed)';
}
return self.firstName() + ' ' + self.lastName() + val;
});
self.firstName.subscribe(function () {
self.valueChanged('First Name');
});
self.lastName.subscribe(function () {
self.valueChanged('Last Name');
});
};
ko.applyBindings(new viewModel());
HTML:
<div>
<label for="fname">First Name:</label>
<input id="fname" data-bind="value: firstName" />
</div>
<div>
<label for="lname">Last Name:</label>
<input id="lname" data-bind="value: lastName" />
</div>
<hr />
<div>Hello <span data-bind="text: fullName"></span></div>
<hr />
<div>Value Changed: <span data-bind="text: valueChanged"></span></div>

knockout observable array not updating after ajax addition

I have an observable array of a complex object. The initial load is fine, and all the expected data looks fine. Now I am working on POSTing new items to that array. NOTE: The observable array is being loaded via ASP.NET ajax web api call.
posting a new item works fine as far as saving it to the database, but my DOM is not getting updated with the new item and I don't know what I am missing.
Here is the entire ViewModel
function ClientList() {
//data
var self = this;
self.initialized = ko.observable(false);
self.clients = ko.observableArray();
self.userId = ko.observable("");
self.name = ko.observable("");
self.logo = ko.observable("");
self.projects = ko.observableArray();
self.clientAddress = ko.observableArray();
self.addClient = function () {
var client = {
UserId: self.userId,
Name: self.name,
Logo: self.logo,
}
client = ko.toJSON(client);
lucidServer.addClient(client);
self.clients.push(client);
}.bind(self);
(function () {
$.ajax({
url: lucidServer.getClients(1),
success: function (data) {
ko.mapping.fromJS(data, {}, self.clients);
self.initialized(true);
}
});
})();
};
function IncompleteStoriesList() {
//data
var self = this;
self.initialized = ko.observable(false);
self.stories = ko.observableArray();
(function () {
$.ajax({
url: lucidServer.getIncompleteStory(1),
success: function (data) {
ko.mapping.fromJS(data, {}, self.stories);
self.initialized(true);
}
});
})();
};
function ViewModel() {
var self = this;
self.clientList = new ClientList();
self.storyList = new IncompleteStoriesList();
}
ko.applyBindings(new ViewModel());
Here is the particular snippet where I am doing the POST (within the ClientList() function).
self.addClient = function () {
self.client = {
UserId: self.userId(),
Name: self.name(),
Logo: self.logo(),
}
//make client object to send to server
var client = ko.toJSON(self.client);
lucidServer.addClient(client);
//push the self.client to the observablearray of clients
self.clients.push(self.client);
}.bind(self);
I verified it is JSON that is sitting inside the client variable, and no error messages are getting thrown, so I am confused. After I add an item and refresh the entire page, it will show up in the list.
EDIT: here is the html associated:
<form data-bind="submit: clientList.addClient">
<div>
<label>userId</label>
<input type="text" data-bind="value: clientList.userId" />
</div>
<div>
<label>name</label>
<input type="text" data-bind="value: clientList.name" />
</div>
<div>
<label>logo</label>
<input type="text" data-bind="value: clientList.logo" />
</div>
<button type="submit">Add</button>
</form>
<!-- ko ifnot: clientList.initialized -->
<span>Loading...</span>
<!-- /ko -->
<ul data-bind="template:{name: 'clientList', foreach:clientList.clients}">
</ul>
And the external template looks like this:
<div id="clientListOutput">
<li><span data-bind="text: name"></span>
<div data-bind="template: {foreach: clientAddress}">
<span data-bind="text: city"></span>
<span data-bind="text: state"></span>
</div>
<hr />
<ul data-bind="template: {foreach: projects}">
<li>
<span data-bind="text: name"></span>
<span data-bind="text: summary"></span>
<span data-bind="text: description"></span>
</li>
</ul>
</li>

I am quite certian you have a typo in your HTML. Here is a working example using ko.observablearray
HTML:
<form data-bind="submit: addItem">
prop1: <input data-bind='value: prop1, valueUpdate: "afterkeydown"' />
prop2: <input data-bind='value: prop2, valueUpdate: "afterkeydown"' />
<button type="submit">Add</button>
<p>Your items:</p>
<div data-bind="foreach: items">
<span data-bind="text: prop1"></span> &nbsp - &nbsp
<span data-bind="text: prop2"></span>
<br />
</div>
</form>
JS:
var SimpleListModel = function() {
this.items = ko.observableArray();
this.prop1 = ko.observable("");
this.prop2 = ko.observable("");
this.addItem = function() {
this.items.push({prop1:this.prop1, prop2: this.prop2});
}.bind(this); // Ensure that "this" is always this view model
};
ko.applyBindings(new SimpleListModel());
http://jsfiddle.net/NjSBg/2/
I suppose it's also possible you forgot to apply the bindings...
Edit
I appologize for posting the wrong fiddle, right one up now.
self.addClient = function () {
var client = {
UserId: self.userId(),
Name: self.name(),
Logo: self.logo()
}
lucidServer.addClient(ko.toJSON(client));
self.clients.push(client);
}.bind(self);
You add the parenthesis to get the current static value of the observable