Develop Reference

How can I toggle the display of a textarea via a button using knockout with the foreach binding?

I am new to knockout. For my problem, I am trying to make it so that for each project, there is a button and textarea. The textarea will be hidden upon page load. If I click the button, it will show the textarea (toggle). Currently, if I click the button, ALL textareas on the page will show, rather than just the corresponding textarea.
I'm hoping the fix for this isn't too dramatic and involving a complete reworking of my code as by some magic, every other functionality has been working thus far. I added the {attr id: guid} (guid is a unique identifier of a project retrieved from the database) statement in an attempt to establish a unique ID so that the right controls were triggered...although that did not work.
Sorry I do not have a working jfiddle to show the issue... I tried to create one but it does not demonstrate the issue.
JS:
//if a cookie exists, extract the data and bind the page with cookie data
if (getCookie('filterCookie')) {
filterCookie = getCookie('filterCookie');
var cookieArray = filterCookie.split(",");
console.log(cookieArray);
$(function () {
var checkboxes = new Array();
for (var i = 0; i < cookieArray.length; i++) {
console.log(i + cookieArray[i]);
checkboxes.push(getCheckboxByValue(cookieArray[i]));
//checkboxes.push(document.querySelectorAll('input[value="' + cookieArray[i] + '"]'));
console.log(checkboxes);
checkboxes[i].checked = true;
}
})
filterCookie = getCookie('filterResultsCookie');
cookieArray = filterCookie.split(",");
filterCookieObj = {};
filterCookieObj.action = "updateProjects";
filterCookieObj.list = cookieArray;
$.ajax("/api/project/", {
type: "POST",
data: JSON.stringify(filterCookieObj)
}).done(function (response) {
proj = response;
ko.cleanNode(c2[0]);
c2.html(original);
ko.applyBindings(new ProjectViewModel(proj), c2[0]);
});
}
//if the cookie doesn't exist, just bind the page
else {
$.ajax("/api/project/", {
type: "POST",
data: JSON.stringify({
action: "getProjects"
})
}).done(function (response) {
proj = response;
ko.cleanNode(c2[0]);
c2.html(original);
ko.applyBindings(new ProjectViewModel(proj), c2[0]);
});
}
View Model:
function ProjectViewModel(proj) {
//console.log(proj);
var self = this;
self.projects = ko.observableArray(proj);
self.show = ko.observable(false);
self.toggleTextArea = function () {
self.show(!self.show());
};
};
HTML:
<!-- ko foreach: projects -->
<div id="eachOppyProject" style="border-bottom: 1px solid #eee;">
<table>
<tbody>
<tr>
<td><a data-bind="attr: { href: '/tools/oppy/' + guid }" style="font-size: 25px;"><span class="link" data-bind=" value: guid, text: name"></span></a></td>
</tr>
<tr data-bind="text: projectDescription"></tr>
<%-- <tr data-bind="text: guid"></tr>--%>
</tbody>
</table>
<span class="forminputtitle">Have you done project this before?</span> <input type="button" value="Yes" data-bind="click: $parent.toggleTextArea" class="btnOppy"/>
<textarea placeholder="Tell us a little of what you've done." data-bind="visible: $parent.show, attr: {'id': guid }" class="form-control newSessionAnalyst" style="height:75px; " /><br />
<span> <input type="checkbox" name="oppyDoProjectAgain" style="padding-top:10px; padding-right:20px;">I'm thinking about doing this again. </span>
<br />
</div><br />
<!-- /ko -->
Spencer:
function ProjectViewModel(proj) {
//console.log(proj);
var self = this;
self.projects = ko.observableArray(proj);
self.projects().forEach(function() { //also tried proj.forEach(function())
self.projects().showComments = ko.observable(false);
self.projects().toggleComments = function () {
self.showComments(!self.showComments());
};
})
};

It's weird that
data-bind="visible: show"
doesn't provide any binding error because context of binding inside ko foreach: project is project not the ProjectViewModel.
Anyway, this solution should solve your problem:
function ViewModel() {
var self = this;
var wrappedProjects = proj.map(function(p) {
return new Project(p);
});
self.projects = ko.observableArray(wrappedProjects);
}
function Project(proj) {
var self = proj;
self.show = ko.observable(false);
self.toggleTextArea = function () {
self.show(!self.show());
}
return self;
}

The problem is that the show observable needs to be defined in the projects array. Currently all the textareas are looking at the same observable. This means you'll have to move the function showTextArea into the projects array as well.
Also you may want to consider renaming your function or getting rid of it entirely. Function names which imply they drive a change directly to the view fly in the face of the MVVM pattern. I'd recommend a name like "toggleComments" as it doesn't reference a view control.
EDIT:
As an example:
function ProjectViewModel(proj) {
//console.log(proj);
var self = this;
self.projects = ko.observableArray(proj);
foreach(var project in self.projects()) {
project.showComments = ko.observable(false);
project.toggleComments = function () {
self.showComments(!self.showComments());
};
}
};
There is probably a much cleaner way to implement this in your project I just wanted to demonstrate my meaning without making a ton of changes to the code you provided.

Knockout js: can't write value from form inside array

I have a script that produces an array of forms, with each form affecting the available options for the next form. The awesome martin booth solved the problem of getting the displayed values to update as new forms are added.
however, I have an observable array (defaultSampleRates) that sits outside the forms array, and for the life of me I can't get the form to push items into that array. I've tried declaring it in a dozen different places in a dozen different ways, but it just won't stick.
basically I need the 'Default sample rate' drop-down to show the sample rates that have been selected in the form above (the user must only be able to choose a default sample rate from a displayed one, rather than from the full list).
Any tips much helpo brain pain. fiddle here: http://jsfiddle.net/3lliot/9vsa4hh7/
html:
<body>
<div style="float:left; width:60%">
<div data-bind="foreach: forms">
<div style="float:left; margin-right:20px"> <span>
<!-- This is a *view* - HTML markup that defines the appearance of your UI -->
<p><span style="color:#AB0002">Sample rate element <span data-bind="text: formNum"></span></span>
</p>
<p>Sample rate (Hz):
<select data-bind="options: sampleRates, value: selectedSampleRate"></select>
</p>
</span>
</div>
</div>
<div style="float:left; clear:both; margin-bottom:20px">
<hr/>
<button data-bind="click: addForm">Add <srate> element</button>
<button data-bind="click: removeForm">Remove</button>
<p>Default sample rate:
<select data-bind="options: defaultSampleRates, value: selectedDefaultSampleRate"></select>
</p>
</div>
</div>
<div style="float:right; width:38%; overflow:scroll; border-left:thin; border-left-style:solid; border-left-color:#dfdfdf;padding-left: 1%"> <span class="code"><audio></span>
<ul data-bind="foreach: forms">
<li>
<!-- render the json --> <span class="code"> <srate id="<span data-bind="text: formNum"></span>">
<br/> <sample_rate><span data-bind="text: selectedSampleRate"></span></sample_rate>
<br/> </srate></span>
</li>
</ul> <span class="code"> <default_srate><span data-bind="text: selectedDefaultSampleRate"></span></default_srate></span>
<br/><span class="code"></audio></span>
</div>
</body>
js:
// This is a simple *viewmodel* - JavaScript that defines the data and behavior of your UI
//window.onload = startKnockout;
window.onload = startKnockout;
var formNum;
var i = -1;
var selectedSampleRates = [];
function Form(allSampleRates, forms) {
var self = this;
// Declare observables
self.selectedSampleRate = ko.observable();
self.formNum = ko.observable();
self.sampleRates = ko.computed(function () {
var formsValue = forms(),
availableSampleRates = ko.utils.arrayFilter(allSampleRates, function (sampleRate) {
return !ko.utils.arrayFirst(formsValue, function (form) {
if (form != self) {
if (form.selectedSampleRate() === sampleRate) {
if (selectedSampleRates.indexOf(sampleRate) === -1) {
selectedSampleRates.push(sampleRate);
}
}
return form.selectedSampleRate() === sampleRate;
} else {
return form != self;
}
});
});
return availableSampleRates;
});
// count how many srate elements there are
i++;
self.formNum = i;
}
var Vm = function () {
var self = this;
var item = 0,
allSampleRates = ['192000', '176400', '96000', '88200', '48000', '44100'];
// declare observables for options outside the srate elements
self.selectedDefaultSampleRate = ko.observable();
// add remove forms stuff
self.forms = ko.observableArray([]);
self.forms.push(new Form(allSampleRates, self.forms));
item++;
self.addForm = function () {
if (i < 5) {
self.forms.push(new Form(allSampleRates, self.forms));
item++;
} else {
alert("Can't have more than 6 <srate> elements!")
}
};
self.removeForm = function () {
if (item > 1) {
self.forms.splice(item - 1, 1);
item--;
i--;
} else {
alert("Must have at least one <srate> element!")
}
};
// define arrays for options outside srate elements
self.defaultSampleRates = ko.observableArray([]);
return self;
}
// Activates knockout.js
function startKnockout() {
ko.applyBindings(new Vm());
};

You can make use of selectedOptions binding to add defaultSample rate.
I changed select sampleRates code to this
<select data-bind="options: sampleRates, value: selectedSampleRate, selectedOptions: $root.defaultSampleRates"></select>
Notice selectedOptions binding there..
Should work as per your need.
Updated Fiddle Demo here : http://jsfiddle.net/rahulrulez/9vsa4hh7/3/
I hope that's what you wanted.

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/

Knockout refresh viewModel using mapping plugin

I am trying refresh a small widget with knockout and the mapping plugin. Here is my code so far:
var AppViewModel = function (data, total, qty) {
var self = this;
self.Products = ko.mapping.fromJS(data, {}, this);
self.CartTotals = ko.observable(total);
self.TotalQty = ko.observable(qty);
};
var func = function(u) {
return $.ajax({ type: "POST", contentType: "application/json; charset=utf-8", data: "{}", dataType: "json", url: u });
},
getQtyTotal = function(b) {
var a = 0;
$.each(b.Table.Rows, function(c) {
a += parseInt(b.Table.Rows[c].Quantity) || 0;
});
return a;
};
$.when(func("/store/MiniCart.aspx/GetShoppingCartInfo"), func("/store/MiniCart.aspx/GetCartTotal")).done(function (jsonA, jsonB) {
var ds = $.parseJSON(jsonA[0].d), ds2 = $.parseJSON(jsonB[0].d), qtyTotal = getQtyTotal(ds);
ko.applyBindings(new AppViewModel(ds, ds2, qtyTotal));
});
<div class="cartDropDownProductItemWrapper" data-bind="foreach: Products.Table.Rows">
<div class="cartDropDownProductItem">
<div class="cartDropDownProductImg">
<img id="cart_details_rpt_prod_image_0" style="height: 71px; width: 55px;" data-bind="attr: { src: ProductImageURL }">
</div>
<div class="cartDropDownProductDesc">
<h6><a data-bind="text: ModelName, attr: { href: ProductLink }"></a></h6>
<div class="cartDropDownProductDescInner">
<div class="cartDropDownColor"> COLOR
<strong><span data-bind="text:ColorName"></span></strong>
</div>
<div class="cartDropDownSize"> SIZE
<strong><span data-bind="text: SizeName"></span></strong>
</div>
<div class="cartDropDownSize"> QTY
<strong><span data-bind="text: Quantity"></span></strong>
</div>
<div class="cartDropDownPrice"> PRICE
<strong><span data-bind="text: UnitCost().toFixed(2)"></span></strong>
</div>
<div class="cartDropDownRemove">
<a href="javascript:void(0);" class="remove" onclick="removeItem('v3BuhngpE4c=')">
<img src="/images/layout/icons/remove.gif" alt="Remove Item">
</a>
</div>
</div>
</div>
<div class="clear"></div>
</div>
<!-- end fo reach -->
<div class="clear"></div>
<div class="cartDropDownButtons clearfix">
<ul class="clearfix">
<li class="countItems"><span data-bind="text: TotalQty"></span> Items</li>
<li class="subTotal" id="subTotal">SUBTOTAL: $<span data-bind="text: CartTotals().toFixed(2)"></span></li>
</ul>
</div>
It renders fine intially but when I try to rebind on a jQuery click event and call:
ko.applyBindings(new AppViewModel(ds, ds2, qtyTotal));
It duplicates the data.

If you start off by creating an empty viewModel... which takes no arguments via it's constructor, like so:
function ViewModel()
{
var self = this;
}
var viewModel = new ViewModel();
...Then you can reference it by name to load in your data using ko.mapping, like this:
ko.mapping.fromJS({ "PropertyName": plainJsObject }, {}, viewModel);
What this does is runs the ko.mapping magic on plainJsObject, and stuffs the result into a property (in this case, called PropertyName) on your viewModel object.
The part you would particularly care about is this:
If you want to refresh the data located in the viewModel.PropertyName with fresh data from the server... you just call the exact same method, and it updates that same property on your viewModel. Just call this same thing again, with new values in your plainJsObject:
ko.mapping.fromJS({ "PropertyName": plainJsObject }, {}, viewModel);
Since you have (I assume) already performed your ko.applyBindings() at some point in your code, this line above will immediately update your view.

You should only need to perform the binding once so just keep that outside of any event driven function calls.
ko.applyBindings(new AppViewModel(ds, ds2, qtyTotal));
I think you are over complicating your code in the above example. I would just return set of Product objects which contains properties for description, unit price, quantity etc and then to calculate the total, use a ko computed variable which will update automatically if a user tries to increase/decrease quantity.
function Product(item) {
var self = this;
self.description = ko.observable(item.description);
self.quantity = ko.observable(item.quantity);
self.unitPrice = ko.observable(item.unitPrice);
self.total = ko.computed(function() {
return self.quantity() * self.unitPrice();
});
}
function AppViewModel() {
var self = this;
self.products = ko.observableArray([]);
self.overvallTotal = ko.computed(function() {
var total = 0;
for (var i = 0; i < self.products().length; i++) {
total += self.products()[i].total;
}
return total;
});
self.removeProduct = function(item) { self.products.remove(item) };
// Load initial state from server, convert it to Product instances
$.getJSON("/store/MiniCart.aspx/GetShoppingCartInfo", function(allData) {
var mappedProducts = $.map(allData, function(item) { return new Product(item) });
self.products(mappedProducts);
});
}
ko.applyBindings(new AppViewModel());
You will have to adjust your server side json results to work with this.

knockout binding print function text instead of variable value

I'm writing a small application in JS and I decided to use Knockout.
Everything work well except from a single value that is not printed correctly and I don't understand why.
This is the html view where error appends (viaggio.arrivo is not visualized, and in place of correct value appears a function code like this "function c(){if(0 <arguments.length){if ..." and so on)
<input data-bind="value: viaggio.arrivo" />
And this is the javascript View Model.
Code is pretty long so I put it in a jsFiddle.
function ViewModel() {
function Viaggiatore(nome, cognome, eta, citta) {
var self = this;
self.nome = nome; self.cognome = cognome;
self.eta = ko.observable(eta);
self.citta = ko.observable(citta);
}
function Viaggio(viaggiatore, partenza, arrivo, mete) {
var self = this;
self.viaggiatore = ko.computed(viaggiatore);
self.partenza = ko.computed(partenza);
self.arrivo = ko.observable(arrivo);
self.mete = ko.computed(mete);
}
self.viaggiatore = new Viaggiatore("Mario", "Rossi", 35, "Como");
self.viaggio = new Viaggio(
function(){ return self.viaggiatore.nome+" "+self.viaggiatore.cognome; },
function(){ return self.viaggiatore.citta; },
"Roma",
function(){ return "mete" ;}
);
}
ko.applyBindings(new ViewModel());

I think you need brackets on one of your parameters, like so:
<p data-bind="text: viaggio.partenza()"></p>
Check out the updated fiddle: http://jsfiddle.net/mGDwy/2/