My router doesn't work as expected

this is the router code

Router.route('screens',  {
  path: '/screenshots/:_id',
  template: 'screens',
  onBeforeAction: function(){
    Session.set( "currentRoute", "screens" );
    Session.set("screenshots", this.params._id);
    this.next();
  }
});

this is the helper for screenshots template

Template.screens.helpers({
    ss: function () {
        var screenshots = Session.get("screenshots");
        return Products.findOne({ _id: screenshots});
    }
});

and am calling it here

<h4><a href="/screenshots/{{_id}}">Click to view the Screenshots</a>

When i click to view the screenshots URL, the URL should be this /screenshots/:_id based on my router configuration, but what i see in the browser is /screenshots/ without the _id and the page shows 404 - NOT FOUND.

Is it possible to create nested routes? because before i click on the link that executes the above route. i will be in this route

Router.route('itemDetails', {
  path: '/item/:_id',
  template: 'itemDetails',
  onBeforeAction: function(){
    Session.set( "currentRoute", "itemDetails" );
    Session.set("itemId", this.params._id);
    this.next();
  }
});

and this route works fine i can see the item _id, is it possible to create another route inside it that has for example this path /item/:_id/screenshots?

I have the _id stored in Session.get("itemId"). Is it possible to call it in the path of the route somehow?

I tried '/item' + '/screenshots' + '/' + Session.get("itemId") but didn't work

or there is other way to solve it?

Solution

The problem is not with the code in the question, the 404 page is occurring due to it not being passed an id into the path, the browser says /screenshots/ and not /screenshots/randomId because it is only being passed that from the link.

As per additions to the question and chat with Behrouz: Because the value is stored in session we can use

Template.registerHelper('session',function(input){ 
    return Session.get(input); 
});

to register a global template helper called session which can be called with {{session session_var_name}} and create the link as below:

<h4><a href="/screenshots/{{session "itemId"}}">Click to view the Screenshots</a>