For my app I'm trying to set an operation on each item of a collection of Widgets. A widget Item contains an url (api rest), and a period. The goal is to loop through a widget collection and do something like this :
//Loop through collection
Meteor.setInterval(function(){
Meteor.call('getData', <Collection>.url,function(e,r){
if(e){
console.error(e);
}else{
//Display the data into the template
}
});
},<Collection>.period);
In the template I'd like to do something like this :
{{#each widgets}}
{{widgetItem}}
{{/each}}
I'd like to know what is the best way to do this ? I heard about Dynamics Templates with Telescope App but I don't know if it would be useful in my case.
The {{#each}} Spacebars magic changes the data context of the elements inside it.
Basically, assuming you have the following or a similar data structure for your widget:
{
templateName : 'coolWidget1',
templateData : { ... }
}
You could write something along the lines of:
{{#each Widgets}}
{{> Template.dynamic template=templateName data=templateData}}
{{/each}}
Where template= and data= are the object parameters you pass to Template.dynamic (it will produce { template : templateName, data : templateData}).
Then you can just pass templateName and templateData thanks to the {{#each}} changing the data context (Spacebars understand that you mean "the templateName and templateData of the current item of the loop).
So that was for the HTML. If you want to share the returned value from the call with the template, search for questions about Session or ReactiveVar, there's already a lot of stuff asked about it.
Related
I am using a helper inside another helper. I am trying to pass a value ‘post_id’, that i am getting dynamically from ‘show_post’ helper.I want to pass it and then use it inside the query that is returning a set of result back to helper. for some reason , app is crashing. Can someone guide me through this.
{{#each show_post}}
{{posttext}}
{{postedBy}}
{{#each show_comment({{post_id}}) }}
//<--- i am passing the value to helper like this.
<span> <p>{{postedBy}}: <h5>{{commenttext}}</h5>{{createdAt}}</p></span>
{{/each}}
{{/each}}
Template.display_block.helpers({
show_post(){
return PostComment.find({parent: 0},{sort: {createdAt: -1}});
}
});
Template.display_block.helpers({
show_comment(e){
var t1 = e;
var now = PostComment.find({post_id:{$regex:new RegExp(’^’ + t1)}});
return now;
}
});
The first helper generates a array(Mongo Db result).I want to use this array’s elements(that are dynamic) in next helper. So i want to use a variable that can hold the value of array element of first helper and then pass it to next helper. In second helper, i want to pass this variable and use this variable to sort a result in Mongo query. I am new to this so i am unable to understand how this instance
Firstly you don't need to wrap helper arguments in double curly braces or parens.
{{#each show_comment post_id}}
Will do what you need.
You're also making life a bit more complicated for yourself than necessary. You can use the current data context through this in your code. Also unclear why you're using a regex unless you're concatenating something to the post _id.
This allows you to simplify down to:
html:
{{#each show_post}}
{{posttext}}
{{postedBy}}
{{#each show_comment}}
<span><p>{{postedBy}}: <h5>{{commenttext}}</h5>{{createdAt}}</p></span>
{{/each}}
{{/each}}
js:
Template.display_block.helpers({
show_comment(){
return PostComment.find({post_id: this._id);
}
});
Let's say I have the following Blaze template helper that fetches some objects from a collection:
PackageInCart: function() {
PackageIds = Carts.findOne({SessionId: SessionID}).Packages;
var PackageObjects = Packages.find({ _id: { $in : PackageIds } } ).fetch();
return PackageObjects;
},
The PackageObjects variable contains objects that have a 'priceperday' property with a certain price value. In the Blaze template, I can easily print this value using:
{{#each PackageInCart}}
<div class="price">{{priceperday}}</div>
{{/each}}
However, what if I want to modify the 'priceperday' value from the Helper function before it gets printed in the template? What would be the correct way to do this?
One solution that came to mind was to make a for loop that iterates over the objects and does something like Object.defineProperty() to change the priceperday property into the new value.
I want to know if there's an easier or quicker way using Blaze methods to modify the object property that gets printed with the curly braces.
If you want to do this using blaze you could do this using another helper.
weeklyPrice: function(priceperday){
return priceperday * 7;
}
Which would be called like this
{{#each PackageInCart}}
<div class="price">{{weeklyPrice priceperday}}</div>
{{/each}}
More info about spacebars helper arguments in the docs
I have the following templates (.html) with their respected managers (.js files):
adminManageCategories
adminAddCategory
adminUpdateCategory
Consider the following:
<template name="adminManageCategories">
{{#each category}}
<div class="clickme">{{title}}</div>
{{/each}}
{{> adminUpdateCategory}}
</template>
Notice the {{> adminUpdateCategory}} is outside of the iteration. This is also a form, and I want to keep it on the same page.
And admin_manage_categories.js
Template.adminManageCategories.events({
"click .clickme": function(event) {
event.preventDefault();
console.log(this._id);
}
});
Notice the console.log() function, which works, as the template manager is smart enough to know the ID of the item that was clicked.
What I want to do is load this items values into the form when clicked. My example above is slim, but in my real data I have a title, sort order, among other things.
So my question is, what is the proper way to pass the _id from the adminManageCategories template to the adminUpdateCategory template, which is the form?
I can hack at this with JavaScript and make things happen, but I think I'm missing a "Meteor way" of doing things.
You need to use a ReactiveVar to store the currently clicked item.
First you need to run meteor add reactive-var, as it's not a package added by default in a standard meteor web app.
JS:
Template.adminManageCategories.created=function(){
// instantiate the reactive-var in the created callback
// we store it as a property of the template instance
this.currentItemId=new ReactiveVar(null);
};
Template.adminManageCategories.helpers({
// this helper reactively returns the currently clicked item
currentItem:function(){
// retrieve the reactive-var from the template instance...
var currentItemId=Template.instance().currentItemId.get();
// ...to fetch the correct collection document
return Items.findOne(currentItemId);
}
});
Template.adminManageCategories.events({
"click .clickme": function(event,template) {
event.preventDefault();
// assign the correct item id to the reactive-var attached to this template instance
template.currentItemId.set(this._id);
}
});
HTML:
<template name="adminManageCategories">
{{#each category}}
<div class="clickme">{{title}}</div>
{{/each}}
<p>Current item title is : {{currentItem.title}}</p>
{{! pass the currentItem as a parameter to your child template this will be
accessible as {{item}} in the HTML and "this.item" in JS helpers or
"this.data.item" in created/rendered/destroyed callbacks}}
{{> adminUpdateCategory item=currentItem}}
</template>
EDIT:
When I initialize the reactive-var in the created callback, I set it to null, this means that until one item is clicked, the helper will return null too and when you'll try to access this.item._id in the adminUpdateCategory this will fail.
The simplest way to solve this issue is maybe to not initialize the variable to null but to the first item in the collection.
Template.adminManageCategories.created=function(){
var firstItem=Items.findOne({},{
sort:{
sortedField:1
}
});
this.currentItemId=new ReactiveVar(firstItem && firstItem._id);
};
There may still be a case when you have 0 items in the collection, so you'll probably end up having to guard against the existence of the item in the JS.
Template.adminUpdateCategory.helpers({
itemProperty:function(){
return this.item && this.item.property;
}
});
I am working on an edit form that has two paths. One is when the user clicks a "New" button, the other is when they click "Edit".
When they click "New", the code sets a form_id Session var to null and a client_id session variable to null, then does a Router.go('formEdit') to load the formEdit template/route.
In the formEdit.js, I do a reactive Template helper (I think that's what they are called, but anyway) like so:
Template.formEdit.form = function() {
var form;
if (Session.equals('form_id', null)) {
// Create empty form
form = {
title: null,
client_id: Session.get('client_id'),
header_fields: [],
form_fields: []
};
} else {
// Load form
form = Forms.findOne({_id: Session.get('form_id')});
}
return form;
}
Basically I check if the form_id was set or not, if so I load it from the Forms collection, if not I create a blank one. I thought this would be pretty simple, really.
The problem is that the created/found form object does not behave in a "reactive" way. If I add header_fields or form_fields the subsequent template code never updates. Both are in a {{#each}} like so:
<template name="formEdit">
...
{{#each header_fields}}
{{> headerFieldOutput}}
{{/each}}
...
{{#each form_fields}}
{{> formFieldOutput}}
{{/each}}
</template>
How do I make it such that I can push header_fields and form_fields onto the form and have the underlying template reactively update the {{#each}}'s?
I think you're going about it a little differently than what the reactive programming methodology in Meteor is expecting.
You're putting the 'display' logic in your template helper, rather than using the template scaffolding itself to do it.
So, declare a very simple template helper, something like this:
Template.formEdit.form = function () {
return forms.findOne(Session.get("form_id"));
};
And then, in your template scaffolding have something like this:
{{#if form}}
{{#with form}}
{{#each header_fields}}
etc...
{{/with}}
{{#else}}
[[insert your blank form scaffolding in here]]...
{{/if}}
Then, as you set your Session form_id variable, you can set it to null to invoke the {{#else}} portion.
There are more details than this (logic in the form submit click handler to identify if you are performing an update or an insert, for example) but hopefully you get the gist of it from this.
You should try to gain a better understanding about how cursors and reactive computations work, as it will help you better understand how to best use the reactive methodology. A good starting place is the parties example (watch the video and walk through the code manually). It's similar to what you're doing, and shows a good way of building your templates for when you don't have a 'selected' object.
Hope this helps!
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.