Iron router dynamic template rendering - templates

Question

In my meteor project, I have added iron:layout, iron:dynamic-template along with iron:router.
My question is, how can you prevent the dynamic template from rendering if there is no data available in the Session? The reason is, the dynamic template is currently being rendered with all html content within it except for data context. This is the problem when the user initially arrives onto the page.
I have a list of names on 'postlist' template. These are 'usernames' of the person who created the post. When a user clicks on the name, the template 'viewpost' is rendered with the relevant data passed...that is fine. But as stated earlier, there is no data context when the user first arrives onto the page. So the see all the content except for the dynamic content.
The following is my current code, with help received from my previous post. Meteor: Render template inside a template
HTML:
<template name="postlist">
<div class="container">
<div class="col-sm-3">
{{#each post}}
<li>{{fullname}}</li>
{{/each}}
</div>
</div>
{{> Template.dynamic template='viewpost' data=currentPost}}
</template>
Click event to capture post _id / helper file:
Template.postlist.helpers({
currentPost: function(){
return Posts.findOne(Session.get('currentPost'));
}
});
Template.postlist.events({
'click li': function(e){
e.preventDefault();
Session.set("currentPost", this._id);
}
});

Answer 1

This is one alternative hack method but understand is not good practice. This is what I am effectively wanting to achieve so you get an idea. But I would like non-hack suggestions for this issue. Thank you.
html:
<template name="viewpost">
{{#if hasData}}
<div class="container">
Post creator is : {{username}} - Info: {{body_text}}
</div>
{{/if}}
</template>
js:
Template.viewpost.helpers({
"hasData":function(){
return Session.get("currentPost");
}
});