added ajax/comment_controller

app/controllers/ajax/comment_controller.rb

@@ -0,0 +1,22 @@
+class Ajax::CommentController < ApplicationController
+  def create
+    params.require :answer
+    params.require :comment
+
+    answer = Answer.find(params[:answer])
+
+    begin
+      current_user.comment(answer, params[:comment])
+    rescue ActiveRecord::RecordInvalid
+      @status = :rec_inv
+      @message = "Your comment is too long."
+      @success = false
+      return
+    end
+
+    @status = :okay
+    @message = "Comment posted successfully."
+    @success = true
+    @render = render_to_string(partial: 'shared/comments', locals: { a: answer })
+  end
+end

app/views/ajax/comment/create.json.jbuilder

@@ -0,0 +1,2 @@
+json.partial! 'ajax/shared/status'
+json.render @render if @render