how to display error messages for a child resource that failed validation

Can anyone explain why this happens?

    mybox:$ ruby script/console
    Loading development environment (Rails 2.3.5)
    >> foo = Foo.new
    => #<Foo id: nil, customer_id: nil, created_at: nil, updated_at:

    >> bar = Bar.new
    => #<Bar id: nil, bundle_id: nil, alias: nil, real: nil, active:
true, list_type: 0, body_record_active: false, created_at: nil,
updated_at: nil>
    >> bar.save
    => false
    >> bar.errors.each_full { |msg| puts msg }
    Real can't be blank
    Real You must supply a valid email
    => ["Real can't be blank", "Real You must supply a valid email"]

So far that is perfect, that is what i want the error message to read.
Now for more:

    >> foo.bars << bar
    => [#<Bar id: nil, bundle_id: nil, alias: nil, real: nil, active:
true, list_type: 0, body_record_active: false, created_at: nil,
updated_at: nil>]
    >> foo.save
    => false
    >> foo.errors.to_xml
    => "<?xml version=\"1.0\" encoding=\"UTF-8\"?>\n<errors>\n
<error>Bars is invalid</error>\n</errors>\n"

That is what I can't figure out. Why am I getting Bars is invalid
versus the error messages displayed above, ["Real can't be blank",
"Real you must supply a valid email"] etc.

My controller simply has a respond_to method with the following in it:

     format.xml { render :xml => @foo.errors, :status
=> :unprocessable_entity }

How do I have this output the real error messages so the user has some
insight into what they did wrong? How do I write my render method in
my controller to show all of the appropriate error messages? And more
important, what will my xml builder view look?

I tend to use the "merge errors" process gleaned from
http://dev.rubyonrails.org/attachment/ticket/11394/merge_bang_errors.patch

http://gist.github.com/376389

Then in your controller you can use:

  @foo.errors.merge! bar.errors

... and the view will work as normal, but with nice errors :slight_smile:

Michael,

Thank you for this, I will try it right away.

Mind if I ask where the best place to put this code in as a best practice for Rails?

Matthew

I am not sure about best practice but I created a file config/
initializers/active_record.rb
with the content of http://gist.github.com/376389 and reload the
server.

as far as I understand, the initializers folder is the place to have
stuff you want to load at startup for all environments.
And what Michael's code is doing is opening the class Errors inside
ActiveRecord module and adding the method merge!

please correct me if it's not accurate.
also, where can I find more insights about the initialize process?

I improved this solution by adding a method that removes the rails
default message ('child model is invalid')
but keeps all the rest:
(notice the call to merge! at the end)

show_child_errors(@key, value, "translation_values")

  def show_child_errors(parent, child, collection_name)
    errors = parent.errors.each{|attr,msg| attr }
    if errors.include?(collection_name)
      #keep all other errors
      keep_errors = parent.errors.select{|attr,msg| attr !=
collection_name }
      parent.errors.clear
      keep_errors.each do |e|
        parent.errors.add(e.first, e.second)
      end
      parent.errors.merge!(child.errors)
    end
  end

I am not

I improved this solution by adding a method that removes the rails
default message ('child model is invalid')
but keeps all the rest:
(notice the call to merge! at the end)

show_child_errors(@key, value, "translation_values")

  def show_child_errors(parent, child, collection_name)
    errors = parent.errors.each{|attr,msg| attr }
    if errors.include?(collection_name)
      #keep all other errors
      keep_errors = parent.errors.select{|attr,msg| attr !=
collection_name }
      parent.errors.clear
      keep_errors.each do |e|
        parent.errors.add(e.first, e.second)
      end
      parent.errors.merge!(child.errors)
    end
  end

I am not