Challenge 2: Reading From params — Solution

class CommentsController < ApplicationController
  def index
    post_id = params[:post_id]   # from the route -- /posts/:post_id/comments
    sort_order = params[:sort]   # from the query string -- ?sort=newest

    @post = Post.find(post_id)
    @comments = sort_order == "newest" ? @post.comments.order(created_at: :desc) : @post.comments
  end
end

=begin
Notes:
- params[:post_id] comes from the nested route pattern
  /posts/:post_id/comments (Chapter 2's nested resources) -- Rails names
  the parameter post_id specifically because the route is nested under
  posts, distinguishing it from a plain :id.
- params[:sort] comes from the query string (?sort=newest) in the actual
  request URL, but it's read through the exact same params hash as
  post_id -- no separate req.query access required, unlike Express.
- The ternary checks sort_order and conditionally orders the post's
  comments -- this demonstrates params values arriving as plain strings
  ("newest"), which is true regardless of whether the original value came
  from a route segment, a query parameter, or (as Challenge 3 shows) a
  form body.
=end