Uncaught More context objects were passed than there are dynamic segments for the route: post

I think you meant to have a route specified.

this.resource('posts', function() {
    this.route('post', { path:'/post/:post_id'})
});

The error sounds like you are passing something like post/12 and you don't have a dynamic segment specified(written as :post_id) The : is the important point that specifies a dynamic segment.

Taken from the Ember.js documentation

The accepted answer works.

However, given where the op is in the example, the more correct fix is to leave the following alone:

this.resource('posts');

and add this below it:

this.resource('post', { path: '/post/:post_id'});