I have a viewmodel whose template I want to change dynamically at runtime when the state of my application changes. I referred to this link
while coming up with my solution.
In my html page I have a div that is bound to a list of view models:
<div class="app"
data-bind="template: {name: templateSelector, foreach: viewModelBackStack}">
</div>
And my templateSelector method looks like this:
this.templateSelector = function(viewModel)
{
if (!_itemTemplate)
{
_itemTemplate = ko.computed(function() {return this.template();}, viewModel);
}
return _itemTemplate();
}
var _itemTemplate;
As can be seen, I am constructing a computed observable which returns viewModel's template.
My viewModel looks like this:
function MyViewModel
{
this.template = ko.observable("MyTemplate");
}
I am changing the value of template as a result of an ajax call being completed and I see that computed observable is called correctly as well (I placed an alert in there to verify it), however the bindings in html does not update the template of my viewmodel. Any help will be appreciated.
UPDATE: I found the bug that was causing it not to work. Basically I was including jquery.tmpl plugin before including knockout.js. Removing jquery.tmpl did the trick !
I don't see a problem with your code, unless it lies in the part where you update the template observable as the result of an AJAX call. Make sure that you have a reference to your view model and are setting it as an observable vm.template(newValue); and not recreating the observable.
Here is your code working: http://jsbin.com/ipijet/5/edit#javascript,html,live
One thing to note is that bindings are already executed within the context of a computed observable, so it is unnecessary to create your own within your templateSelector function.
You can simply create a function that returns your observable directly like:
this.getTemplate = function(data) {
return data.template();
};
http://jsbin.com/ipijet/3/edit#javascript,html,live
Here is an article that I wrote a while back on this topic: http://www.knockmeout.net/2011/03/quick-tip-dynamically-changing.html
Related
I just want to run the template string against an object and examine the result
I have a string that is a template. I've "compiled" it. Now I want to run it against an object and examine the result.
But this doesn't work:
var template = '<div>{{#each items}}<div>{{item}}</div>{{/each}}</div>';
var compiled = Ember.Handlebars.compile(template);
var result = compiled({ items: [1, 2, 3] }); // ERRORS
What I want to get is the DOM result of running my compiled string against an object. In other words, a set of DOM elements that looks something like this:
<div>
<div>1</div>
<div>2</div>
<div>3</div>
</div>
It appears that Ember.Handlebars.compile is very tightly coupled to other parts of an Ember application, to the point it expects a lot of things to be populated in the context I'm passing ot the compiled function. I have yet to figure out what all of these things are, or if there is a better way to create a context to pass to the compiled function.
Other things:
I don't want to use plain "non-Ember" Handlebars.
I'd like to avoid creating an Ember Application if I can.
I don't really want to answer questions about "why" I want to do this. This is what I want to do. :P
Why do you want to do this? ;)
Honestly the easiest way to do this will be to create a view. Ember hooks up a bunch of fancy rendering stuff when it calls compile due to the data binding etc, so it's difficult to create it straight from the compile function (it passes in a slew of additional stuff, like buffers etc...)
var view = Ember.View.extend({
template:Ember.Handlebars.compile('hello <div>{{#each item in view.items}}<div>{{item}}</div>{{/each}}</div>')
});
var foo = view.create({ items: [1, 2, 3] });
foo.appendTo('#blah');
Example
http://emberjs.jsbin.com/qeyenuyi/1/edit
// you must wait for all bindings to sync before you can check the contents of #blah:
var empty = $('#blah').html(); // this will be empty
Ember.run.next(function(){
var notEmpty = $('#blah').html(); // this will have the proper result in it
});
or you can hook up to the didInsertElement callback
var foo = view.create(blah);
foo.didInsertElement = function(){
console.log(foo.$().html());
}
foo.appendTo('#blah');
http://emberjs.jsbin.com/qeyenuyi/6/edit
The bindings are still in tact when you create a Ember handlebars template, so you can modify the object passed in and it will update the template.
http://emberjs.jsbin.com/qeyenuyi/2/edit
So let's say I'm storing <div>{{name}}</div> and <div>{{age}}</div> in my database.
Then I want to take the first HTML string and render it in a template - {{> template1}} which just renders the first string with the {{name}} handlebar in it. Then I want to give that newly generated template/html data, so that it can fill in the handlebar with the actual name from the database, so that we would get <div>John</div>. I've tried doing
<template name="firstTemplate">
{{#with dataGetter}}
{{> template1}}
{{/with}}
</template>
Where template1 is defined as
<template name="template1">
{{{templateInfo}}}
</template>
And templateInfo is the helper that returns the aforementioned html string with the handlebar in it from the database.
dataGetter is just this (just an example, I'm working with differently named collections)
Template.firstTemplate.dataGetter = function() {
return Users.findOne({_id: Session.get("userID")});
}
I can't get the {{name}} to populate. I've tried it a couple of different ways, but it seems like Meteor doesn't understand that the handlebars in the string need to be evaluated with the data. I'm on 0.7.0 so no Blaze, I can't upgrade at the moment due to the other packages I'm using, they just don't have 0.8+ version support as of yet. Any ideas on how I can get this to work are much appreciated.
In 1.0 none of the methods described above work. I got this to work with the function below defined in the client code. The key was to pass the options { isTemplate: true} to the compile function.
var compileTemplate = function(name, html_text) {
try {
var compiled = SpacebarsCompiler.compile(html_text, { isTemplate:true });
var renderer = eval(compiled);
console.log('redered:',renderer);
//Template[name] = new Template(name,renderer);
UI.Template.__define__(name, renderer);
} catch (err){
console.log('Error compiling template:' + html_text);
console.log(err.message);
}
};
The you can call with something like this on the client:
compileTemplate('faceplate', '<span>Hello!!!!!!{{_id}}</span>');
This will render with a UI dynamic in your html
{{> Template.dynamic template='faceplate'}}
You can actually compile strings to templates yourself using the spacebars compiler.. You just have to use meteor add spacebars-compiler to add it to your project.
In projects using 0.8.x
var compiled = Spacebars.compile("<div>{{name}}</div> and <div>{{age}}</div>");
var rendered = eval(compiled);
Template["dynamicTemplate"] = UI.Component.extend({
kind: "dynamicTemplate",
render: rendered
});
In projects using 0.9.x
var compiled = SpacebarsCompiler.compile("<div>{{name}}</div> and <div>{{age}}</div>");
var renderer = eval(compiled);
Template["dynamicTemplate"] = Template.__create__("Template.dynamicTemplate", rendered);
Following #user3354036's answer :
var compileTemplate = function(name, html_text) {
try {
var compiled = SpacebarsCompiler.compile(html_text, { isTemplate:true }),
renderer = eval(compiled);
console.log('redered:',renderer);
//Template[name] = new Template(name,renderer);
UI.Template.__define__(name, renderer);
} catch (err) {
console.log('Error compiling template:' + html_text);
console.log(err.message);
}
};
1) Add this in your HTML
{{> Template.dynamic template=template}}
2) Call the compileTemplate method.
compileTemplate('faceplate', '<span>Hello!!!!!!{{_id}}</span>');
Session.set('templateName','faceplate');
Save the template name in a Session variable. The importance of this is explained in the next point.
3) Write a helper function to return the template name. I have used Session variable to do so. This is important if you are adding the dynamic content on a click event or if the parent template has already been rendered. Otherwise you will never see the dynamic template getting rendered.
'template' : function() {
return Session.get('templateName');
}
4) Write this is the rendered method of the parent template. This is to reset the Session variable.
Session.set('templateName','');
This worked for me. Hope it helps someone.
If you need to dynamically compile complex templates, I would suggest Kelly's answer.
Otherwise, you have two options:
Create every template variation, then dynamically choose the right template:
eg, create your templates
<template name="displayName">{{name}}</template>
<template name="displayAge">{{age}}</template>
And then include them dynamically with
{{> Template.dynamic template=templateName}}
Where templateName is a helper that returns "age" or "name"
If your templates are simple, just perform the substitution yourself. You can use Spacebars.SafeString to return HTML.
function simpleTemplate(template, values){
return template.replace(/{{\w+}}/g, function(sub) {
var p = sub.substr(2,sub.length-4);
if(values[p] != null) { return _.escape(values[p]); }
else { return ""; }
})
}
Template.template1.helpers({
templateInfo: function(){
// In this context this/self refers to the "user" data
var templateText = getTemplateString();
return Spacebars.SafeString(
simpleTemplate(templateText, this)
);
}
Luckily, the solution to this entire problem and any other problems like it has been provided to the Meteor API in the form of the Blaze package, which is the core Meteor package that makes reactive templates possible. If you take a look at the linked documentation, the Blaze package provides a long list of functions that allow for a wide range of solutions for programmatically creating, rendering, and removing both reactive and non-reactive content.
In order to solve the above described problem, you would need to do the following things:
First, anticipate the different HTML chunks that would need to be dynamically rendered for the application. In this case, these chunks would be <div>{{name}}</div> and <div>{{age}}</div>, but they could really be anything that is valid HTML (although it is not yet part of the public API, in the future developers will have more options for defining this content in a more dynamic way, as mentioned here in the documentation). You would put these into small template definitions like so:
<template name="nameDiv">
<div>{{name}}</div>
</template>
and
<template name="ageDiv">
<div>{{age}}</div>
</template>
Second, the definition for the firstTemplate template would need to be altered to contain an HTML node that can be referenced programmatically, like so:
<template name="firstTemplate">
<div></div>
</template>
You would then need to have logic defined for your firstTemplate template that takes advantage of some of the functions provided by the Blaze package, namely Blaze.With, Blaze.render, and Blaze.remove (although you could alter the following logic and take advantage of the Blaze.renderWithData function instead; it is all based on your personal preference for how you want to define your logic - I only provide one possible solution below for the sake of explanation).
Template.firstTemplate.onRendered(function() {
var dataContext = Template.currentData();
var unrenderedView = Blaze.With(dataContext, function() {
// Define some logic to determine if name/age template should be rendered
// Return either Template.nameDiv or Template.ageDiv
});
var currentTemplate = Template.instance();
var renderedView = Blaze.render(unrenderedView, currentTemplate.firstNode);
currentTemplate.renderedView = renderedView;
});
Template.firstTemplate.onDestroyed(function() {
var renderedView = Template.instance().renderedView;
Blaze.remove(renderedView);
});
So what we are doing here in the onRendered function for your firstTemplate template is dynamically determining which of the pieces of data that we want to render onto the page (either name or age in your case) and using the Blaze.With() function to create an unrendered view of that template using the data context of the firstTemplate template. Then, we select the firstTemplate template element node that we want the dynamically generated content to be contained in and pass both objects into the Meteor.render() function, which renders the unrendered view onto the page with the specified element node as the parent node of the rendered content.
If you read the details for the Blaze.render() function, you will see that this rendered content will remain reactive until the rendered view is removed using the Blaze.remove() function, or the specified parent node is removed from the DOM. In my example above, I am taking the reference to the rendered view that I received from the call to Blaze.render() and saving it directly on the template object. I do this so that when the template itself is destroyed, I can manually remove the rendered view in the onDestroyed() callback function and be assured that it is truly destroyed.
A very simple way is to include in the onRendered event a call to the global Blaze object.
Blaze.renderWithData(Template[template_name], data ,document.getElementById(template_id))
I have a fiddle http://jsfiddle.net/kristaps_petersons/9wteJ/2/ it loads 3 objects and shows them in a view. Data is shown alright, but i can not filter it before i show it.
This
nodes: function(){
this.get('controller.content').filter(function(item, idx, en){
console.log('should log this atleast 3x')
})
return this.get('controller.content')
}.property('controller.content')
method is called when template iterates over array of values, but it never goes in to the loop and print console.log('should log this atleast 3x') why is that?
You are trying to replace controller.content while also binding to it. You need to define another property, such as filteredContent and bind it to controller.content. Take a look at how Ember.SortableMixin computes the variable arrangedContent for controllers with a sortProperties variable defined. Using that method as a template I would implement it like this:
filteredContent: Ember.computed('content', function() {
var content = this.get('content');
return this.filter(function(item, idx, en) {
console.log('should log this atleast 3x');
});
}).cacheable()
This should be implemented in the controller, not the view. The controller is the place for data manipulation, computed properties, and bindings.
Then bind the view layout to filteredContent instead of content to show the filtered data. Then both the original content and the filtered content are available.
Ok i got it working, but it feels a bit strange. First i moved method to Controller class and changed it to look like this:
nodes: function(){
console.log('BEFORE should log this atleast 3x', this.get('content.length'))
this.get('content').forEach(function(item, idx, en){
console.log('should log this atleast 3x')
})
console.log('AFTER should log this atleast 3x', this.get('content.length'))
return this.get('content')
}.property('content').cacheable()
as it should be same as buuda's recomedation, because as i understand from docs .poperty() is the same as Ember.computed. As it was still not working, i changed .property('content') to .property('content.#each') and it was working. Fiddle: http://jsfiddle.net/kristaps_petersons/9wteJ/21/ . I guess, that tempate first creates a binding to controller.content and as content itself does not change does not notify this method again, instead template pulls data as it becomes available.
Here's a link to a jsfiddle: http://jsfiddle.net/Qt972/
When you run the fiddle you'll see a name and a button to make the "person" say hello. This works fine, however the "event" is undefined.
An even simpeler case also fails:
http://jsfiddle.net/CCg2K/1/
Does anyone know how I can fix this issue?
When you do a console.log(arguments) inside your action callback you can see that there are actually 3 parameters passed. The first one is the view, the second is the event and the third is the context.
You can rewrite your edit action like this:
edit: function(view, event, context) {
var target = event.target;
...
}
UPDATE: since commit 657a2664 - available in release 0.9.6 I guess - only a single event parameter is passed which has the view and context as properties. So if you want to access those you have to do the following:
edit: function(event) {
var view = event.view;
var context = event.context;
...
}
How do I test which view was rendered from a controller action if what I get is a T4MVC_ActionResult? Under normal circumstances I should be able to directly use TestHelper's methods, like in the examples:
pooController.Details().AssertViewRendered().ForView("Details")
...but, since through T4MVC I get a T4MVC_ActionResult instead of a ViewResult, the part AssertViewRendered<>().ForView("Details") fails. What alternative do I have if I want to test which view was invoked?
UPDATE:
Here's the test code:
[TestMethod]
public void Theme_Controller_Details_Action_Returns_Details_View()
{
var builder = new TestControllerBuilder();
var mockThemeRepository = new Mock<IThemeRepository>();
var themeController = builder.CreateController<Evalgrid.Website.Controllers.ThemeController>(mockThemeRepository.Object);
builder.InitializeController(themeController);
var result = themeController.Details();
result.AssertViewRendered().ForView("Details");
}
I used the debugger setting a breakpoint after the result line, and its variable type is T4MVC_ActionResult, while themeController is Evalgrid.Website.controllers.ThemeController. Note that I have used the fully qualified name of the controller.
I get this:
Expected result to be of type
ViewResult. It is actually of type
T4MVC_ActionResult.
I don't know what's going on.
Actually, T4MVC should not make a difference here. If you directly instantiate your controller and call an action method, you'll get the same thing back whether you use T4MVC or not. i.e. you won't get a T4MVC_ActionResult.
It's only when you write MVC.Foo.Details() that you'll get a T4MVC_ActionResult. That's because MVC.Foo returns an instance of a derived class which does special thing, and not directly your controller class.
Does that make sense?
Update: I'm confused, as looking at the sources for TestControllerBuilder.CreateController, it has:
public T CreateController<T>(params object[] constructorArgs) where T : Controller
{
var controller = (Controller)Activator.CreateInstance(typeof(T), constructorArgs);
InitializeController(controller);
return controller as T;
}
So it's directly instantiating the type that you pass in, which should just call your normal action.
One question about your code: does your Details action method take any parameters? If so, that would explain the problem, as you're calling it with no params, which would be a T4MVC method added in the partial class.