In Meteor, if the below is my HTML,
<template name="myTemplate">
The value is {{value}}
</template>
I can define the value in two ways
Template.myTemplate.helpers
value: ->
'insideHelper1'
Template.myTemplate.value =
'outsideHelper1'
The first way is using helpers as documented here (http://docs.meteor.com/#template_helpers) whereas the second way is using the Live Template examples as defined here (http://docs.meteor.com/#livehtmltemplates)
Just wondering, what is the difference between the two and when should I use one over the other?
They're exactly the same.
If you use .helpers, it actually just adds it to Template..
It depends on your coding style. You may prefer to use .helpers since it makes cleaner code if you have many helpers on the same template.
One small technically way they're different is Template.helpers adds the helpers to your Meteor app when your Meteor app starts up, whereas using the Template.helpername adds it before. So if you need to overwrite any helpers, you could use the .helpers method. The one that runs last will have the active helper.
Related
Is there any way to detect when the {{>Template.dynamic template=content}} changes and then run some functions ?
You can wrap your functions in a template.autorun() block, in the dynamic template you are rendering (in his rendered function) .
If you need to follow it from outside, you can use the tracker Deps feature: you declare the change in the autorun block.
Is there a way to check if a specific Template has been rendered, other than by using Sessions, i.e. the Template is accessible for other external functions to use?
A good example is that I want to use Blaze.renderWithData, but need to know that the Template is availabel beforehand.
If you want to see if a template has been rendered, put a flag in the onRendered callback. If you don't like Session vars use a reactive var or dict & include the inverse in the onDestroyed. Store that reactive-whatever under your package object's global. As an alternative, if you know where it might be rendered to, you can use Blaze.getView on the element where it should appear and if it returns, you know you have it, e.g. Blaze.getView($('.foo')[0])
Also consider asking yourself why you can't use spacebars or embed the rendering directly in the onRendered callback. Using Blaze.renderWithData is fairly uncommon.
Is there a way to include an existing dom-element through Handlebars, while being able to keep a reference to said dom-element?
to explain:
I have a jquery-element $el of which I want to include the dom-element ($el[0]) in a handlebars template.
I have some jquery code that uses $el.html("new stuff") after handlebars has included the template (again: this template contains $el[0]
The usual solution would be to rewrite the code by providing a selector so jquery can access the element. However, the code that needs to change $el doesn't know where in the template $el[0] will be used, since this is configurable. Having to specify the selector by config is possible obviously but this doesn't really feel dry to me.
So, any way to do this?
I implemented this with a handlebars helper that injects a unique id and post-render keeps a ref from uniqueid -> element to bind.
On postrender I simply find the elements with the unique-ids and update each element to it's mapped el to bind.
I'm a bit of a newb in Meteor so this is possibly a trivial question for you Meteor masters out there.
I use a template which has a couple of child templates:
<template name="parent">
{{> child1}}
{{> child2}}
</template>
I noticed that parent.rendered and child1.rendered functions are invoked when reactive data under child2 changes.
My understanding of meteor docs is that only child2.rendered should be called. So, what I am seeing should not happen, yet for a reason which is beyond me, it does.
To rule out any noise, I gutted the child1 template (to contain only an empty div). Still, its rendered function is called.
Can anyone provide insight?
As of Meteor 0.7.0.1, the parent template will be re-rendered but the sibling child templates will not.
Here is a simple example Meteor app that shows this in action:
https://github.com/alanning/meteor-subtemplate-isolate-test
Keep in mind that Meteor UI is getting a drastic overhaul before Meteor 1.0 lands so a lot of things may change with respect to how templating works.
Just hypothesizing here, but I think the entire page rerenders when any reactive data changes. For example, if you were to have data in Session.get('test') and the only time the value of that is inserted into the DOM is in child2, I believe the entire page still rerenders.
I am using findOne just to fetch one certain element for my collection.
However, when I do that, all my template functions containing those collections are re-run and the content refreshed. The content is similar, the problem is I am applying styles to some of those elements, and these updates just reset everything as well. More importantly: those refreshes are completely useless.
For example, I have this template:
Template.content.cars = function () {
alert("I AM RERUN!");
return Cars.find();
};
And in another function, I am doing this:
Cars.findOne({ _id: Session.get('current_car') }, {});
Why would be the first template re-run? Am I doing something wrong?
I'm not sure why your first template would be re-run: are you sure something else isn't going on?
But as a general non-answer to your question: you should expect that a template which depends on the entirety of a collection will be re-run many times (for instance as the data loads incrementally when the page first renders). With meteor you need to write your HTML/CSS in such a way that this re-rendering won't cause problems.
Without knowing more about your problem I can't really say more than that.