Can I dynamically build templates on the server and send the result to clients? I found SpacebarsCompiler.compile() returns a string representing render function, but how to convert it to a template?
You could try this,
/**
* #contextObject the object you want to evaluate in your template
* #templateName the name of you template <template name="">
* return html rendered.
*/
function renderTemplate(contextObject, templateName){
return Blaze.toHTML(Blaze.With(contextObject, function() { return Template[templateName]; }));
}
I don't Im been using this in the client side I don't sure if will work on the server side but you could give it a try.
if you have a template html like
<template name="thisIsMyTemplateName">
<div>
{{name}}
</div>
</template>
then if you have an object like var myobject = { name : "my name" }
you could use the function like
myHtml = renderTemplate(myobject, "thisIsMyTemplateName");
you will get in return the plain html that you could append or do whatever you want like
$(document).append(myhtml);
Related
I'd like to be able to call (global) template helpers from inclusion template tags.
So this works;
Static version:
{{>volcanoTable pagination=5)}}
But i'd like to get the value of pagination per user by using Template helper function named getPref(key,defaultvalue).
"Dynamic version":
{{>volcanoTable pagination=getPref("pagination",5) }}
which gives error:
Expected space
...ue pagination=getPref('a',5) )}}
Also tried different versions, but they didn't work either;
like {{>volcanoTable pagination=getPref "pagination" "5" }}
Or is there another way to get the same desired results?
You can just create a helper which returns a context object. For example:
Template.myTemplate.helpers({
myPagination: function(n) {
// extract the default pagination for the user
var pagination = Meteor.user().profile.pagination;
if (pagination) {
return {pagination: pagination};
} else {
return {pagination: n};
}
}
});
Which you can use like this:
<template name='myTemplate'>
{{> volcanoTable myPagination 6}}
</template>
In this case, the volcanoTable would get a context of {pagination: 6} only if there was no default pagination property for the user. Of course you could make myPagination a global helper if it's useful outside of this template.
Is it possible for a parent Meteor template to access a subtemplate directly? Ideally, I'd like to use templates a widgets with an API. I was hoping for something like this:
mypage.html
<template name="myPage">
<div class="widgetContainer"></div>
<button>submit</button>
</template>
mypage.js
Template.myPage.rendered = function(){
this.myWidgetInstance = UI.render(Template.myWidget)
UI.insert(this.myWidgetInstance, $('.widgetContainer')[0]);
}
Template.myPage.events({
'click button': function(e, template){
// I don't want this logic to live inside of mywidget.js.
// I also don't want this template to know about the <input> field directly.
var val = template.data.myWidgetInstance.getMyValue();
}
});
mywidget.html
<template name="myWidget">
<input></input>
</template>
mywidget.js
Template.myWidget.getValue = function(){
return this.$('input').val();
}
The above doesn't work because myWidgetInstance.getMyValue() doesn't exist. There doesn't appear to be a way for external code to access template helper functions on an instance.
Is anyone using Meteor templates in the way I'm trying to use them above? Or is this better suited for a separate jQuery widget? If so, it'd be a shame because I still want my widget template to benefit from the features Meteor provides.
It is possible to access subtemplate helper function.
Your example will work once you apply few fixes:
fix 1 : getValue() instead of getMyValue()
Template.myPage.events({
'click button': function(e, template){
// I don't want this logic to live inside of mywidget.js.
// I also don't want this template to know about the <input> field directly.
var val = template.myWidgetInstance.getValue();
console.log(val);
}
});
fix 2 : $('input').val(); instead this.$('input').val();
Template.myWidget.getValue = function(){
return $('input').val();
}
fix 3 : <input> should have no close tag.
<template name="myWidget">
<input type="text" value="sample value">
</template>
I am struggling to figure out the basic pattern for populating a template with data from a call to an external API in Meteor.
These are the elements in play
A fresh Meteor project, created by running meteor create monkeyproject
The URL of an external API that returns a JSON array. Let's say it's example.com/api/getmonkeys. It returns an array of monkeys, each with a different name.
A Handlebar template called monkeyTemplate with an {{#each}} loop. Let's say it's this:
<template name="monkeyTemplate">
{{# each monkeys}}
One of our monkeys is named {{name}}. <br>
{{/each}}
<input type="button" id="reload" value="Reload monkeys" />
</template>
What I want to happen
When the page loads fill monkeyTemplate with monkeys from our external URL.
When the user clicks the button, call the external URL again to reload the monkeys.
The question
What is a standard pattern for doing the above in Meteor? At the risk of cluttering up the question, I'll include some starting points, as I understand them.
We can populate the template with whatever we return from our Template.monkeyTemplate.monkeys function. How do we fill it with content from an external URL, given that the page will load before the external request is finished?
We can get our JSON by using Meteor.HTTP.call("GET", "http://example.com/api/getmonkeys", callback ). Where do we put this request, and what do we put into our callback function in this situation?
We can control what happens on the server side and what happens on the client side by using the Meteor.isServer/Meteor.isClient conditions, or by putting our code into files called client and server folders. What code needs to be on the server side vs. the client side?
We determine what happens when the button is clicked by attaching a function to Template.monkeyTemplate.events['click #reload']. What goes into our callback function in this situation?
I will refrain from cluttering up the question with my crappy code. I am not looking for anyone to write or rewrite an application for me—I am just looking for the guidelines, standard patterns, best practices, and gotchas. Hopefully this will be instructive to other beginners as well.
I'm not sure if this is the "standard" template, but it serves the purpose pretty well.
Set up two data helpers for the template, monkeys and loading. First one will display the actual data once it's fetched, the latter will be responsible for notifying user that the data is not yet fetched.
Set up a dependency for these helpers.
In created function of the template, set loading helper to true and fetch the data with HTTP call.
In the callback, set the template data and fire the dependency.
html
<template name="monkeys">
{{#if loading}}
<div>Loading...</div>
{{/if}}
{{#if error}}
<div>Error!</div>
{{/if}}
{{#each monkeys}}
<div>{{name}}</div>
{{/each}}
<div><button class="monkeys-reloadMonkeys">Reload</button></div>
</template>
js
var array = null;
var dep = new Deps.Dependency();
Template.monkeys.created = function() {
reloadMonkeys();
};
Template.monkeys.events({
'click .monkeys-reloadButton': function(e,t) {
reloadMonkeys();
};
});
var reloadMonkeys = function() {
array = null;
dep.changed();
HTTP.get('http://example.com/api/getmonkeys', function(error, result) {
if(!error && result) {
array = result;
} else {
array = 0;
}
dep.changed();
});
};
Template.monkeys.monkeys = function() {
dep.depend();
return array ? array : [];
};
Template.monkeys.loading = function() {
dep.depend();
return array === null;
};
Template.monkeys.error = function() {
dep.depend();
return array === 0;
};
I'm struggling with an issue that I will explain giving a simple demo.
There's following very simple document in People Collection.
{
"_id" : "vxmLRndHgNocZouJg",
"fname" : "John" ,
"nicks" : [ "Johnny" , "Jo"]
}
Now let's consider following templates. Basically I display username and a list of nicknames with input field for adding more nicknames.
<head>
<title>test</title>
</head>
<body>
{{> name}}<br/>
{{> nicks}}
</body>
<template name="name">
<input type="text" value="{{fname}}"/>
</template>
<template name="nicks">
{{#each nicks}}
<div>{{this}}</div>
{{else}}
no nicks yet
{{/each}}
<input type="text" name="nicks"/>
<input type="submit"/>
</template>
My client javascript code is as follows:
Template.name.fname = function() {
return People.findOne({"fname" : "John"},{
transform : function(doc) {
return doc.fname;
}
});
}
Template.name.rendered = function() {
console.log('Template "name" rendered!');
}
Template.nicks.nicks = function() {
var john = People.findOne({"fname" : "John"});
if(john) return john.nicks;
}
Template.nicks.events({
'click input[type="submit"]' : function () {
var johnId = People.findOne({"fname" : "John"})._id; // demo code
People.update(johnId,{
$addToSet : {
nicks : $('input[name="nicks"]').val()
}
})
}
});
My problem is that after adding nickname (update of nicks field in a document) template name is re-rendered (I know because I console.log it). When I query People collection to provide data for name template I use transform option so changes in nicks field shouldn't have impact on name template.
Meteor docs supports this:
Cursors are a reactive data source. The first time you retrieve a cursor's documents with fetch, map, or forEach inside a reactive computation (eg, a template or autorun), Meteor will register a dependency on the underlying data. Any change to the collection that changes the documents in a cursor will trigger a recomputation.
Why template name is re-rendered then?
The template is re-rendered because you change the People collection.
When you alter the People collection, Meteor automatically assumes that everything that it provides data to needs to be recalculated. (Which your name template does via Template.name.fname.
Even though you transform the output of the cursor, the People collection has changed in some way. The query is done before the transform is used, in other words, its not the transform that is looked at but the whole collection.
Meteor thinks that perhaps your document with {'fname':'John'} may have some other field that might have changed and it needs to requery it to check (which the nicks field has been altered). The transform is then applied after the requery.
Your HTML might not actually change at this point, only if the cursor returns something different will the html be changed.
If it becomes an issue in any scenario (i.e forms being cleared or DOM being changed when it shouldn't be) you can use the {{#isolate}} {{/isolate}} blocks to ensure that only everything inside them is re-rendered and nothing outside.
Is there any way to get the object of the current iteration in Handlebars?
code:
<script id="HandleBarTemplate1" type="text/x-handlebars-template">
{{#each objArr}}
<img src="{{objField1}}"/>
<strong>Name:</strong> {{objField2}}
<input type="button" onclick="processObject({{.}});"/>
{{/each}}
</script>
I've mentioned processObject({{.}}) That is incorrect. That's where I need a replacement/Solution.Hope you get what I'm tryin' to say.
The contents of objArr might look like
var objArr = [{objField1:"smith.jpg",objField2:"Smith"},{objField1:"jane.jpg",objField2:"Jane"},...]
Template compilation code is:
var source = document.getElementById("HandleBarTemplate1").innerHTML;
var compiledTemplate = Handlebars.compile(source);
var html = compiledTemplate({objArr:objArr});
If I could get the reference to the Object, then It's so easy to process the data. Rather than passing a field to the function and searching through entire array to get the required object and then process it.
I Prefer a solution without a custom block helper/custom expression helper but if none exists, I'd rather go for a custom block helper. Any solution without searching through the entire array is welcome!
I would suggest a different route.
Knowing that you already have a reference to objArr, make a global or name-spaced variable pointing to it.
For example: window.objArr = objArr;
Create your click handler that does whatever you wish:
function processObject(key){
}
call that with your key inside your template:
< script id="HandleBarTemplate1" type="text/x-handlebars-template">
{{#each objArr}}
<img src="{{objField1}}"/>
<strong>Name:</strong> {{objField2}}
<input type="button" onclick="processObject({{objField2}});"/>
{{/each}}
</script>
Other alternatives:
Customer Handler.
Other alternatives:
If you can't create a reference to objArray, you might could store the properties of the object within data- attributes if you're using html5. processObject could then retrieve them.
I do this with a Handlebars helper and an array of context objects.
Somewhere we have an array of context objects, which will store a reference to each context object we need to reference:
var ContextObjects = [];
We need to register a Handlebars helper function that stores the current context object in the array for us when we place "{{obj}}" in the template. The helper returns the index of the object in the array, which is what gets rendered:
// Must be function and not lambda to preserve the correct 'this'
Handlebars.registerHelper("obj", function ()
{
var contextObject = this; // the current context object
var index = ContextObjects.indexOf(contextObject);
if (index < 0)
{
index = ContextObjects.length;
ContextObjects[index] = contextObject;
}
return index;
});
Next we need a function to retrieve the object from the index on the element:
// Get the context object for the current event (e.g. click or context).
function GetContextObject(event)
{
var $e = $(event.currentTarget);
var index = $e.attr("data-obj");
return ContextObjects[index];
}
We tie them together in the template something like this:
{{#each Items}}
<div data-obj="{{obj}}" onclick="DoSomething(GetContextObject(event));">...</div>
{{/each}}
Which may render something like this:
<div data-obj="0" onclick="DoSomething(GetContextObject(event));">...</div>
<div data-obj="1" onclick="DoSomething(GetContextObject(event));">...</div>
<div data-obj="2" onclick="DoSomething(GetContextObject(event));">...</div>
...