I'm stumped here. I can't get it to find a collection from the onCreated method. If I log the data.source_id right before the call and then do the same lookup in the console, it finds it. Is there something special about onCreated or something? Am I just doing it wrong?
client/setup.js
Meteor.subscribe('source_elements');
Meteor.subscribe('internal_elements');
client/submit.js
Router.route('/element/submit', function() {
this.render('submit', {
data: {
source_id: this.params.query.source_id,
},
});
});
Template.submit.onCreated(function() {
var data = Template.instance().data;
var source_element = SourceElements.findOne({'_id': data.source_id});
console.log(source_element); // EMPTY!!
});
Template.submit.helpers({
element: function() {
var data = Template.instance().data;
var source_element = SourceElements.findOne({'_id': data.source_id});
console.log(source_element); // RESULT!!
return source_element;
},
});
Subscriptions are asynchronous. It looks like you are creating the template before the data has arrived at the client. By the time you execute the find in the console, the client has received the data.
Inside your onCreated function, you could use Tracker.autorun to specify a function that will be rerun when the SourceElements collection changes (that's what all template helpers do behind the scenes):
Tracker.autorun(function() {
var element = SourceElements.findOne({'_id': data.source_id});
console.log(element);
});
This function will be called immediately. At this point, findOne will probably return undefined because the subscription is not ready yet. Once the data has arrived, the function will be called again and you can process the returned elements.
Related
I am trying to get the value of a field from a document returned via a subscription. The subscription is placed inside a helper function. I had a callback function within the subscription return this value and then I assigned the return value to a variable (see code). Finally, I had the helper return this value. However, the value returned is a subscription object (?) and I can't seem to get anything out of it.
Code:
Template.myTemplate.helpers({
'returnUser':function(){
var id = Session.get('currentUserId');
var xyz = Meteor.subscribe('subscriptionName',id,function(){
var user = accounts.find().fetch({_id: id})[0].username;
return user;
}
return xyz;
}
});
Any help will be much appreciated. :)
You have to load first your subscriptions when the template is created, this creates an instance of your data with Minimongo.
Template.myTemplate.onCreated(function () {
var self = this;
self.autorun(function() {
self.subscribe('subscriptionName',id);
});
});
Then in the helper, you can make a query to retrieve your data
Template.myTemplate.helpers({
'returnUser': function(){
var id = Session.get('currentUserId');
return accounts.findOne(id).username;
}
});
I have a list of tasks and I want to load a list of corresponding comments when I click one of the Tasks.
Iron router code:
Router.route('/taskComments/:_id', function () {
var item = Tasks.findOne(this.params._id);
this.render('commentList', {data: item});
},
{
name: 'taskComments',
fastRender: true
}
);
Template helpers:
Template.commentList.helpers({
comments: function(){
return Comments.find({taskID: this._id});
});
I am able to access the task id (this._id) in the above snippet, but it does not seem to work for onCreated:
Template.commentList.onCreated(function(){
this.subscribe("comments",this._id);
});
When I console log this it gives me the following object:
Notice that there is no _id and data is also null.
You can use Template.currentData() inside of this callback to access reactive data context of the template instance. The Computation is automatically stopped when the template is destroyed.
Template.commentList.onCreated(function(){
var self = this;
var dataContext = Template.currentData()
self.subscribe("comments",dataContext._id);
});
Consider the following code :
Template.fullDoc.rendered = function() {
// Get triggered whenever the selected document id changes
this.autorun(function() {
var docId = isolateValue(function() {
return Template.currentData().selectedDoc._id;
});
...
});
}
This code doesn't work. Inside isolateValue(), Template.currentData() sometimes triggers an exception: Exception from Tracker recompute function: Error: There is no current view (this corresponds to the fact that Template.instance() returns null).
So how do you set a reactive dependency on a subpart of a template data context?
You could recreate the isolateValue behaviour in a way which doesn't cause Template.instance() to get set to null sometimes.
$ meteor add reactive-var
Template.fullDoc.rendered = function () {
var docIdVar = new ReactiveVar();
this.autorun(function () {
docIdVar.set(Template.currentData().selectedDoc._id);
});
this.autorun(function () {
var docId = docIdVar.get();
// ...
});
}
This makes use of the fact that setting a ReactiveVar to the same value it already has will not trigger an invalidation. (By default this only works for primitives; for objects you'll need to pass a custom equalsFunc when you construct the ReactiveVar. If _id is a string, you're fine. If it's ObjectID you probably aren't.)
Context : I am using a Collection Params to call method from the Server to a C app. The C app does its stuff and then calls the server by RPC to send me the results. With the result, I get the Params ID to delete the corresponding element.
With the deletion of the Element of Params, the C app gets a removed message. I want to prevent this behavior to avoid overloading the C app of messages.
I've thinked about implementing the removed event into the Publish method on the server to prevent the server from informing the C app. I just want the C app to be inform about added events.
On the Meteor Doc, there is an example of implementation of added and removed but I don't understand it. Can someone help me ?
I've tried this (don't work at all) :
Meteor.publish('expert_mode_parameters', function ()
{
var self = this;
var handle = Expert_Mode_Parameters.find().observeChanges({
added: function ()
{
return Expert_Mode_Parameters.find();
},
removed: function ()
{
return [];
}
});
self.ready();
self.onStop(function () {
handle.stop();
});
}
It looks like your goal is to subscribe to a data set but only receive added messages, not changed or removed.
The below code should do this:
Meteor.publish('expert_mode_parameters', function () {
var self = this;
var handle = Expert_Mode_Parameters.find().observe({
added: function (document) {
self.added("expert_mode_parameters", document._id, document);
}
});
self.ready();
self.onStop(function () {
handle.stop();
});
}
The concept is, you're watching the results of Expert_Mode_Parameters.find() and then calling self.added(document) when there is a new item. The same thing can easily be expanded to include changed.
I've been trying to access the this.userId variable from within a Meteor.methods call, but it doesn't seem to work when I try to call the method via Meteor.setTimeout or Meteor.setInterval.
This is what I've got:
if (Meteor.is_server) {
Meteor.methods({
getAccessToken : function() {
try {
console.log(this.userId);
return Meteor.users.findOne({_id: this.userId}).services.facebook.accessToken;
} catch(e) {
return null;
}
}
});
var fetch_feed = function() {
console.log(Meteor.call("getAccessToken"));
[...] // A bunch of other code
};
Meteor.startup(function() {
Meteor.setInterval(fetch_feed, 60000); // fetch a facebook group feed every minute
Meteor.setTimeout(fetch_feed, 3000); // initially fetch the feed after 3 seconds
});
}
Watching the terminal log, the this.userId always returns a null. But if I try calling the method from the client side, or through the console, it returns the correct ID.
How come this doesn't work from within a Meteor.setInterval? Is it a bug or am I doing something wrong?
Meteor userId's are associated with client connections. The server may interact with many clients and this.userId inside a method will tell you which client has asked for the method to be run.
If the server uses Meteor.call() to run a method then it will not have a userId since it is not running for any client.
The methods allow clients to call for functions to be run on the server. For things the server will trigger itself a javascript function will do.
There is a solution I used - sometimes you do not want to make the method a function but really want it to remain a method. In that case, a hack to make this work:
var uniqueVar_D8kMWHtMMZJRCraiJ = Meteor.userId();
Meteor.setTimeout(function() {
// hack to make Meteor.userId() work on next async
// call to current method
if(! Meteor._userId) Meteor._userId = Meteor.userId;
Meteor.userId = function() {
return Meteor._userId() ||Â uniqueVar_D8kMWHtMMZJRCraiJ
};
Meteor.apply(methodName, args);
}
, 100);
Some brief explanation: we save Meteor.userId in Meteor._userId and overwrite Meteor.userId with a function that returns Meteor._userId() if it is true and otherwise the historic value of Meteor.userId() before any of this happened. That historic value is saved in an impossible to occur twice var name so that no context conflicts can happen.