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class CommentsController < ApplicationController
# since comments are always deplayed from inside their
# parent's show action , none of the actions that have
# templates are created. (index, show, new or edit)
def create
# Read the context_object first.
# The context_objct method end up returning
# Article.find(5) or Proyect.find(6), depending on
# what the context_type and the parent_id are in the
# params hash. So it returns an specific record one that
# will be the parent in the create action.
@commentable= context_object()
# We scope the build method so that rails will automaticly fill
# the commentable_type and commentable_id values on the comments
# table. Remember that commentable was the alias used for article
# and proyect in the models.
# That is all you need to create a comment inside the correspongin parent
@comment =[:comment])
flash[:notice] = "Successfully created comment."
respond_to do |format|
format.html{ redirect_to @commentable}
render :action => 'new'
def update
# Read create first
# The only mayor diference between this and the create
# action is that this time im passing ad include option,
# all this does is tell active record that when it fetches
# the article or proyect it should also fetch its comments
# in the same query. The include option is passed to the
# context_object option who them recives it as finder_options
# and uses in in the find
@commentable= context_object.includes(:comments)
@comment = @commentable.comments.find(params[:id])
if @comment.update_attributes(params[:comment])
flash[:notice] = "Successfully updated comment."
redirect_to @commentable
render :action => 'edit'
# there is no need to scope the comment user the @commentable
# instance and the context_type since we are going to
# find the comment by its id which is an unique value in the database.
def destroy
@comment = Comment.find(params[:id])
flash[:notice] = "Successfully destroyed comment."
# :back is an alias to env[:HTTP_REFERER]
# and holds the page that sent us to this action
# redirecting to :back saves us having from to
# use context_object to figure out how to
# redirect to the parent
redirect_to :back
# this function here is the reason why :constraint => {:context_type => "articles"} was added to
# routes file, everytime the params hash comes from withing the comments nested path, the router adds
# the context type to the params hash, so i access that value by reading from params hash and
# accessing the inner value params[:constraint] out of which [:context_type] is one, and you can pull
# the value of a hash inside a hash the way you pull the value of a nested array. In each context the value is
# returned telling if am accesing comments from inside the articles or the proyects, so those are the 2 values i can get
# but they are only strings, and are in plural, so i make it singular with singularize and make them constants with
# contantize, that way the values become Article and Proyect, the name of the models! so now they are model
# names and i call find on them, but i still need the to pass an id to the find,so how do i get the id ? look lower
# at the context_id method.
# *finder_options just passes down any option pass to the context_object method and uses it in the find
# you will see wa this does when you read the update action.
def context_object
params[:constraint][:context_type].singularize.classify.constantize.find( context_id )
# this here is the action the gets the id of the parent model of the polymorphic association, just as the previous
# method is catches where is the the comments action been called and uses that to build a parent_id symbol and then
# uses that to get the value out of the params hash, becuase the params hash also carries this value it the path
# /articles/:article_id/comments or /articles/:proyect_id/comments passed by the route and extracts the corresponding
# id of the parent in the given path, so what im doing at the end, is using context_type to build the param
# :article_id or :proyect_id depending on the case and then using that symbol to get the proper params[:article_id] or
# params[:proyect_id]
def context_id
params["#{ params[:constraint][:context_type].singularize }_id"]
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