Rails - Jan 2008 - Validation and error messages in has_many association in single form with parent

I am having trouble with validation and user-friendly error messages
when I create a new "Spot" and an associated (has_many)
"Title".

I have the following models:
---------------------------------------------------------------------
class Spot < ActiveRecord::Base
  has_many :titles,
            :dependent => :destroy,
            :conditions => "active = 1"

  validates_length_of :address,
                  :in => 1..1000,
                  :too_short => "The Address cannot be blank.",
                  :too_long => "The Address needs to be less than %d
characters"
end

class Title < ActiveRecord::Base
  belongs_to :spot

  validates_length_of :title,
                  :in => 1..255,
                  :too_short => "The Title cannot be blank.",
                  :too_long => "The Title needs to be less than %d
characters",
                  :message => nil
end

Then in my new.html.ebr view I use multiple objects in
error_messages_for to show both validation results, and I use
fields_for to generate the Spot portion the form.
----------------------------------------------------------------------
error_messages_for (:object => [@spot.titles[0], @spot])
<% form_for(@spot) do |f| %>

  <% fields_for(@spot.titles[0]) do |t_form| %>
    <p>
      <b>Title</b><br />
      <%= t_form.text_field :title %>
    </p>
  <% end %>

  <p>
    <b>Address</b><br />
    <%= f.text_area :address %>
  </p>

  <p>
    <%= f.submit "Create" %>
  </p>
<% end %>

Here are the new and create actions in the Spots controller.
----------------------------------------------------------------------
def new
    @spot = Spot.new
    @spot.titles[0] = Title.new

    respond_to do |format|
      format.html # new.html.erb
      format.xml  { render :xml => @spot }
    end
  end

def create
    @spot = Spot.new(params[:spot])
    @spot.titles[0] = Title.new(params[:title])
    #set the new title
    @spot.titles[0].active = 1

    respond_to do |format|
      if @spot.save
        flash[:notice] = ''Spot was successfully created.''
        format.html { redirect_to(@spot) }
        format.xml  { render :xml => @spot, :status
=> :created, :location => @spot }
      else
        format.html { render :action => "new" }
        format.xml  { render :xml => @spot.errors, :status
=> :unprocessable_entity }
      end
    end
  end

Everything works, but I am seeing a couple of strange things that I
don''t really understand.

First, the title is being validated, which is good, but I don''t have
to include a validates_associated call in the Spot model like I would
if this was a has_one relationship. Why is that?

Second, when there is an error in the title field, error_messages_for
(:object => [@spot.titles[0], @spot]) displays two errors, the first
one is what I expect "The Title cannot be blank." but I also get an
additional error "Titles is invalid." This error is part of the @spot
object. I would like to be able to remove this message, because it is
a duplicate, and because I don''t know where to change the verbiage to
something more user friendly.

Thanks for any information.
Nick Carlevaris


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NickCB wrote:
> First, the title is being validated, which is good, but I don''t
have
> to include a validates_associated call in the Spot model like I would
> if this was a has_one relationship. Why is that?
> 
> Second, when there is an error in the title field, error_messages_for
> (:object => [@spot.titles[0], @spot]) displays two errors, the first
> one is what I expect "The Title cannot be blank." but I also get
an
> additional error "Titles is invalid." This error is part of the
@spot
> object. I would like to be able to remove this message, because it is
> a duplicate, and because I don''t know where to change the verbiage
to
> something more user friendly.
Active Record does automatic internal validation of has_many associations.
You can turn it off by putting

   def validate_associated_records_for_titles() end

after the has_many call. You can then add your own validates_associated
call with your own error message.  Call validates_associated with
:message => nil if you want no error message displayed for the parent
object.

-- 
We develop, watch us RoR, in numbers too big to ignore.


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Worked like a charm.
-- 
Posted via http://www.ruby-forum.com/.

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