Knockout containerless 'with' binding not working - javascript

This containerless with binding doesn't set the bindingContext as I would expect; it's still set to the containing parent of ladder.
<!-- ko with:ladder -->
<table>
//Context here is the $root object, not $root.ladder
//some foreach binding here
</table>
Add 4 pages
<!-- /ko -->
This containerful method works fine though.
<table class="ladder-table" data-bind="with:ladder">
//the context is correctly set to ladder in this instance
//some foreach binding here
</table>
<br />
Add 4 pages
Anyone know what's up with that? Google didn't give any results.

The problem is with Durandal, not Knockout, as this answer explains:
containerless statements of knockoutjs is not working in hottowel SPA?
In short, Durandal allows only one root element per view.
goodView.html
<div>
<--ko foreach:stuff-->
//stuff
<--/ko-->
</div>
badView.html
<div>
<stuff/>
</div>
<--ko foreach:stuff--> //these elements are stripped out
//stuff
<--/ko-->
Thanks #nemesv

Related

AngularJS modal window scope

I have problem with scopes of controllers. I'm using controller as directive and I have code similar to this example:
<div ng-controller="ItemsController as itemCtrl">
<table> .. some data ... </table>
<a ng-click="itemCtrl.createItem()">Create new item</a>
</div>
<div id="create-form" ng-controller="ItemFormController as itemFormCtrl">
<form ng-submit="itemFornCtrl.saveItem()">... form inputs ...</form>
</div>
<div id="edit-items" ng-controller="MultipleItemsEdit as multiEditCtrl">
... table with some data ....
<!-- I need this -->
<a ng-click="itemCtrl.createItem()">Create new item</a>
<!-- -->
</div>
Basically there are 3 isolated scopes. But I need to break this isolation and call methods from one scope on another.
I'm currently using ugly "delegate" kind of hack.
Controllers and their methods are not so interesting, only interesting methods are ItemsController.createItem():
this.createItem = function(dataCollection) {
angular.element( $("#create-form) ).controller().createNewItem(dataCollection);
}
and ItemFormController.createNewItem(dataCollection):
this.createNewItem = function(dataCollection) {
... some initialization ....
$("#add-item").dialog( "open" );
}
I need to call createNewItem method on ItemFormController to show modal box. But I cannot do it directly, so I'm using method createItem which gets the create-form element and its controller and calls createNewItem method on it. It is kind of a delegate. But I don't like it, because I need to call createNewItem from many places of my code and I don't want to populate all my controllers with this kind of delegate methods.
Maybe I could make these delegates on some kind of root controller, but isn't there any better solution?
You can nest the edit controller scope in the list controller scope by simply nesting the divs (move the div with ng-controller="MultipleItemsEdit as multiEditCtrl" into the div with ng-controller="ItemsController as itemCtrl"). That way the you can call the method directly.

Angular JS model changes not reflected in view when ng-repeat and custom directives are combined

I have the following fiddle setup to demonstrate what I am experiencing.
http://jsfiddle.net/BjornJohnson/ndxnG/25/
My controller uses these objects: page => rows => columns => pieces. A page has rows. A row has columns. A column has pieces.
There is a custom directive ("piece"). The point of the directive is to be able to provide different types of HTML elements based on the "type" of the piece (so-called dynamic templating).
I keep running into problems when I remove pieces from a column. I am modifying the model, but it's not reflected in the view. It works when the ng-repeat is on a wrapper, but not on the custom directive itself, so I think something is clashing with the ng-repeat directive.
I apologize in advance for using all caps, but I CANNOT USE A WRAPPER DIV FOR THE NG-REPEAT :)
The code in question is both in the view and the directive.
Here's part of the custom directive:
var template = templates[scope.piece.key];
var replacement = $($compile(template)(scope));
element.replaceWith(replacement);
Here's part of the view:
<div ng-repeat="column in row.data.columns" ng-class="column.data.clss">
<!-- notice wrapper for ng-repeat - THIS VIOLATES MY REQUIREMENTS -->
<div ng-repeat="piece in column.data.pieces">
<piece></piece>
</div>
</div>
versus...
<div ng-repeat="column in row.data.columns" ng-class="column.data.clss">
<!-- notice ng-repeat on custom directive -->
<piece ng-repeat="piece in column.data.pieces"></piece>
</div>

Knockout js - && in if condition and containerless binding

I am displaying a list of items and if the items are not available I have to display a default message. Now, I have to check whether the object has been created and then check the object has the list in it.
So now, I am doing the below and it works it creates unnecessary dom elements. But, when I do the same with the containerless binding it doesn't seem to work and also is there an && syntax for if in KO
<span data-bind="if: object">
<span data-bind="if: !object().property">
<p> The list is not available </p>
</span>
</span> // Works
<!-- ko if: object -->
<!-- ko if: !object().property -->
<p> The list is not available </p>
<!-- /ko -->
<!-- /ko --> // Doesn't work
Thanks
As mentioned by CodeThug, using the solutions you provided would display the message until ko.applyBindings have finished. A more verbose solution, but that would avoid the problem without relying on CSS, is to use dynamic templates as shown in the following jsfiddle:
http://jsfiddle.net/sAkb4/1/
This will create the valid markup inside the virtual element only when the ko.applyBindings is done.
<!-- ko template: { name: dinamycList } -->
<!-- /ko -->
<script type="text/html" id="empty-template">
... list is NOT available markup ...
</script>
<script type="text/html" id="list-template">
... list is available markup ...
</script>
Being dinamycList a function that returns the name of the template according to the verifications you want for a valid list.
EDIT:
Reading thru your last comment made me think if the behaviour that you want is to display the "not avaiable template" only after calculating the list and the property is false, if thats the case, the following fiddle will fix the last one to provide the right condition.
http://jsfiddle.net/sAkb4/3/
The "if" condition in template will handle the moment after knockout is ready, but before the list is. If the condition gets too messy, i would advise to put it inside a ko.computed for a clear markup.
<!-- ko template: { name: dinamycList, if: object() !== undefined && object().property !== undefined } -->
<!-- /ko -->
As you have seen, the element exists in the DOM, and it won't be removed until the ko.applyBindings call is finished. Thus the momentary display of this message.
I'd try hiding the entire section of the DOM and show a loading indicator instead. When ko/ajax is done, the loading indicator can then be removed and the markup you care about displayed.
Alternately, you could see if your page is taking a while to load and try to improve the load time of the page. The chrome profiling tools can help with this.
THis is very easy with my Convention over configuration lib
http://jsfiddle.net/VVb4P/
Just this and the lib will do the templatating for you
this.items.subscribe(function(items) {
if(items.length === 0) {
this.items.push(new MyApp.EmptyViewModel());
}
}, this);

KO cannot find template with ID

I've used Knockout templates before, so I'm not sure why this isn't working for me.
I tried two different styles of ko markup, neither work.
<!-- more nesting levels -->
<div class="cal-day-tps" data-bind="foreach: timePeriods">
<div class="cal-day-tp-cont">
<div data-bind="template: { name: 'tp-ed-templ', data: $data }"></div>
//both of these methods fail
<!-- ko template: { name: 'tp-ed-templ', data: $data } -->
<!-- /ko -->
</div>
</div>
<!-- /more nesting levels -->
<script type="text/html" id="tp-ed-templ">
<!-- bunch of markup -->
</script>
I just get the error "Cannot find template with ID tp-ed-templ".
Probably just a typo, but I haven't been able to find it.
I'm using KO in the context of Durandal, though this shouldn't make a difference.
Tried declaring the template before usage, didn't help.
Someone else ran into the same thing with no solution either
It seems to be an issue with Durandal, not Knockout.
I tried some extremely simple cases in vanilla durandal setups, and it still does the same thing. Even tried putting the script in the same nested location as the binding, no dice.
The short answer: You can't currently use Knockout templates inside of Durandal.
However, as nemesv pointed out, if you put your named template outside of Durandal, ko is able to find them. For example, anywhere outside of the <div id="applicationHost"></div> element.
The other workarounds are to either use Durandal's compose functionality, or just inline the templates as anonymous.
Knockout templates will probably be supported in the near future.
I finally dug these answers up on the Durandal google group,
Mixing knockout templates with durandal compose
knockout can't find templates inside of views
The issue is that the KO template element must exist in the DOM before the Durandal view is bound. This is because the view is bound before it is inserted into the DOM so any contained templates cannot be resolved by ID.
Using a function that returns an observable can be used to later re-trigger a template binding .. it works, but is wonky. (An if binding could be used for similar effect.)
// bind to this in markup:
// <div data-bind="template: {name: $root.templateName, .. }">
vm.templateName = function () {
return vm.TemplateId();
};
// Changing this will trigger an observable in the KO template binding;
// don't ask me why we have to pass in a function to 'name' ..
vm.TemplateId = ko.observable("dummy-template-id-that-exists");
// After the view is attached the correct template element is in the DOM
// so we can trigger the template to (re-)bind and it will find it.
function viewAttached () {
vm.TemplateId("the-real-template-id");
}

KnockoutJs - handling several areas with the same fields

I have several regions with repeatable content which is generated on the server-side. I use knockout-js to dynamically hide/show regions within areas. My markup is like the following:
<div>
<input type="checkbox" data-bind="checked: a1" />
<div data-bind="visible: a1">region0</div>
</div>
<div>
<input type="checkbox" data-bind="checked: a2" />
<div data-bind="visible: a2">region1</div>
</div>
<script>
var viewModel = {
a1: ko.observable(false),
a2: ko.observable(false)
};
ko.applyBindings(viewModel);
</script>
Lets say I have 10 such regions. Is there a more convenient/better way to achieve the same?
Lets say, that I explicitly do not want to use foreach binding and generate markup on the client (for site to be accessible with disabled js).
Is there any way to omit viewModel specification (part within script tags), since it feels to me that knockout could detect and auto-create fields for me?
P.S. I'm a JS-novice, so excuse me for simple questions :)
Is there any way to omit viewModel specification (part within script tags), since it feels to me that knockout could detect and auto-create fields for me?
Although I prefer Knockout personally, you might want to take a look at Angular. Angular does automatically create view model properties as this example shows.

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