Question

I have this in the Model:

  after_create do |comment|
   CommentMailer.comment_email(self).deliver
  end

This in CommentMailer:

  class CommentMailer < ActionMailer::Base
  helper ActionView::Helpers::UrlHelper
  include CommentHelper
  helper :comment
 def comment_email(user, comment, commentable)
   mail(to: user.email,
        subject: "You have left a comment",
        from: "[e-mail]",
        bcc: "[e-mail]")
 end
end

And this in CommentHelper:

module CommentHelper
  def find_commentable
    @comment = Comment.find(params[:comment])
    params.each do |name, value|
      if name =~ /(.+)_id$/
        return $1.classify.constantize.find(value)
      end
    end
    nil
  end
end

I’m getting this error:

Started POST "/requests/6/comments" for 127.0.0.1 at 2012-11-30 17:28:55 -0800
Processing by CommentsController#create as HTML
  Parameters: {"utf8"=>"✓", "authenticity_token"=>"R62NH5/EE34FPapEqy7mfpa0wKz18GtSdhH8MGYq2Ec=", "comment"=>{"content"=>"post", "show"=>"true"}, "commit"=>"Create Comment", "request_id"=>"6"}
  User Load (0.3ms)  SELECT "users".* FROM "users" WHERE "users"."id" = 2 ORDER BY users.created_at DESC LIMIT 1
  Request Load (0.3ms)  SELECT "requests".* FROM "requests" WHERE "requests"."id" = $1 LIMIT 1  [["id", "6"]]
  CACHE (0.0ms)  SELECT "requests".* FROM "requests" WHERE "requests"."id" = $1 LIMIT 1  [["id", "6"]]
   (0.1ms)  BEGIN
  SQL (0.4ms)  INSERT INTO "comments" ("commentable_id", "commentable_type", "content", "created_at", "show", "updated_at", "user_id") VALUES ($1, $2, $3, $4, $5, $6, $7) RETURNING "id"  [["commentable_id", 6], ["commentable_type", "Request"], ["content", "post"], ["created_at", Sat, 01 Dec 2012 01:28:55 UTC +00:00], ["show", true], ["updated_at", Sat, 01 Dec 2012 01:28:55 UTC +00:00], ["user_id", 2]]
   (0.2ms)  ROLLBACK
Completed 500 Internal Server Error in 136ms

ArgumentError (wrong number of arguments (1 for 3)):
  app/mailers/comment_mailer.rb:5:in `comment_email'
  app/models/comment.rb:27:in `block in <class:Comment>'
  app/controllers/comments_controller.rb:22:in `create'

Answer 1

Looks like simple typos.

Line 7, as noted in the exception:

commentable = @comment.commentable

So, the issues:

• You’re calling @comment.commentabe, but @comment is nil
• Hence the error: undefined method 'commentable' for nil:NilClass
• @comment is nil in your mailer method because you’re passing it in as comment NOT @comment, yet you’re trying to reference it as @comment.

Also, why are you passing in commentable as a parameter, but on line 7 you’re setting commentable again – this is redundant? Just use the already available commentable variable that you’re passing in as a param. In fact, you seem to be doing this with several variables, yet I can’t tell (because you don’t show the mailer template) whether or not you’re actually using them.

It could be that you could use something simpler like:

So, this should (probably) work:

def comment_email(user, comment, commentable)
  mail(to: user.email,
       subject: "You have left a comment",
       from: "[e-mail]",
       bcc: "[e-mail]")
end

If you post your mail template (so I can see what the body of the email looks like) I can help you get the variables into the template.