Single Post subscription not working in my meteor code - mongodb

Question

I want to display only single elements based on the ID passed. I am using the subscribe and publish method of meteor for the same, also FlowRouter for Routing. When i try to get the data using findOne and pass the Id, it does't return any data, but when i do find({}), it gets all the data and displays it, not sure why findOne is not working..
Note : I am trying to fetch record based on the Object ID(_id) provided by MongoDB.
posts = Mongo.collection("allPosts");
<Template name="stdSingleView">
{{#if Template.subscriptionsReady}}
{{#with studenthistory}}
{{id}} - {{name}}
{{/with}}
{{else}}
Loading....
{{/if}}
</Template>
Template.stdSingleView.onCreated(function(){
var self = this;
self.autorun(function(){
var Id = FlowRouter.getParam('id');
self.subscribe('singlePost', Id);
});
});
Template.stdSingleView.helpers({
studenthistory: function(){
var id= FlowRouter.getParam('id');
return posts.findOne({_id: id});
}
});
if (Meteor.isServer) {
Meteor.publish("allposts", function() {
return posts.find({});
});
Meteor.publish('singlePost', function(id) {
check(id, String);
return posts.find({_id: id});
});
}
pages.route( '/:id', {
name: 'singleView',
action: function( params ) {
BlazeLayout.render('stdSingleView');
}
});

Answer 1

When you do findOne using _id, Please wrap it to the New Mongo.ObjectID and then pass it.
Try this code :
Meteor.publish('singleStudent', function(id) {
check(id, String);
return attendanceRegCol.find({"_id": new Mongo.ObjectID(id)});
});
Template.studentSingleView.helpers({
studenthistory: function(){
var id= FlowRouter.getParam('id');
return attendanceRegCol.findOne({"_id": new Mongo.ObjectID(id)});
}
});

Answer 2

find will return a cursor, which contains only one document. You need to loop through that in order to get the data, or You change the helper into findOne
Template.stdSingleView.helpers({
studenthistory: function(){
var id= FlowRouter.getParam('id');
return posts.findOne({_id: id});
}
});