Creating Variable Number of Models in One Form (Page 7 of 7)

This has been extremely helpful for me as well.

I'm running into a problem with validating an associated model, however. I have a Photo model (based on attachment_fu) that belongs to a ResourceItem model. In my view for creating a new resource_item, users can add or remove photos and then click "create." This works great if they have uploaded a photo or if they have removed all photo fields.

If they leave a blank photo field, however, there will be a validation failure. ResourceItem will try to validate associated photos; the associated photos will be blank and therefore won't validate_as_attachment.

What I'd like to do is check to see if the photo file_field is blank for each photo. If it is, I'd like to remove it from my @resource_item object. Only then will I save the resource_item. I'm not sure how to do this -- or if this is even the best way to go. Any suggestions would be great!

Below is the pertinent code:

# Photo.rb includes 
belongs_to :resource_item
validates_as_attachment
# ResourceItem.rb includes 
class ResourceItem < ActiveRecord::Base
  has_many :photos, :dependent => :delete_all
  after_update :save_photos           
  validates_associated :photos
# resource_items_controller.rb
  def new
    @resource_item = ResourceItem.new
    2.times { @resource_item.photos.build }
  end
  def create
    @resource_item = ResourceItem.new(params[:resource_item])
    
    # put some code in here that would remove photos if user hasn't uploaded anything -- so that validation doesn't fail
    
    if @resource_item.save
      flash[:notice] = "You have successfully created a resource!"
      respond_to do |wants|
        wants.html { redirect_to resource_items_url }
        wants.xml  { render :xml => @resource_item.to_xml }
      end
    else 
      render :action => 'new'
    end     
  end
# from _add_photo.html.erb:
<div class="add_photo">
    <% fields_for "resource_item[photo_attributes][]", add_photo do |photo_form| %>
            Photo 1:<%= photo_form.file_field 'uploaded_data', :index => nil %><br />
            caption: <%= photo_form.text_field :caption, :index => nil %><br />
            <% if add_photo.new_record? %>
                <%= link_to_function "remove", "$(this).up('.add_photo').remove()" %>
            <% else %>
                <%= link_to_function "remove", "mark_for_destroy(this)" %>
                <%= photo_form.hidden_field :id, :index => nil %>
                <%= photo_form.hidden_field :should_destroy, :index => nil, :class => 'should_destroy' %>
            <% end %>
<% end %>
</div>

First off, thanks for a fantastic tutorial. I can't believe I blew an hour trying to figure out a problem with the controller.

Using Rails 2.0. When adding another "task", nothing happened and I kept getting the following in development.log:
ActionController::MissingTemplate (Missing template people/add_address.html.erb in view path /home/Scott/track/app/views):

Turns out I didn't notice I need a respond_to in the controller for add_task

# in projects_controller.rb
def add_task
  @task = Task.new
  
  respond_to do |format|
    format.js
  end  
end

OK, so I've got a nice nested hash using this string for the fields_for first parameter...

 <% fields_for "lessons_edited[#{lesson}][assignments][#{index}]", assignment do |assignment_form| %>
...stuff here...
<% end %>

Now my problem...

The assignment form consists of dynamic drop-downs updated with observe_field. So, the final partial which is used to select the 'segment_id' for the assignment isn't working as I would expect/hope. The 'assignment_form' method from the form builder block doesn't seem to like my select control... neither collection_select nor select. When I use...

 assignment_form.text_field :segment_id

When I use...

 assignment_form.select :segment_id, @segments.collect {|s| [s.id, s.full_name]}

ActionView::TemplateError (wrong number of arguments (3 for 0)) on line #3 of app/views/lessons/_segments.rhtml:
...
3: <%= assignment_form.select :segment_id, @segments.collect {|s| [s.id, s.full_name]}, {} %>

assignment_form.collection_select :segment_id, @segments, :id, :full_name

ActionView::TemplateError (undefined method `collection_select' for "#<ActionView::Helpers::FormBuilder:0x3461d80>":String) on line #3 of app/views/lessons/_segments.rhtml:
...
3: <%= assignment_form.collection_select :segment_id, @segments, :id, :full_name %>

hi i'm really a newbie in rails.
i'm doing a project about online rostering.
if i have 2 tables (model) - person, work_shift
is this "Creating Variable Number of Models in One Form" method can be use to make this type of interface (see below):

#it will loop n person i have in table person.
#day will be entered manually using drop down/text field.

Person | shift_day
john   | monday
doe    | tuesday
dann   | wednesday
rob    | thursday
carl   | friday

(save shift)

i want to know if i click (save shift) it will save that 5 new records in shift table.

by the way,
this is what in the table person: id, name
this is what in the table work_shift: person_id, shift_day

i tried this tutorial before in my other project. in 1 form, it will add 2 records. 1 record in user table and 1 record in student table. (work like a charm, thank you!)
e.g.
user - id = 1, name = john
student - id = 1, user_id = 1

haze: If you're using Rails 2.0, I don't think that the inplace editor is in the core anymore. I believe it's been moved into a plugin.

Hey All,

I am running into a strange problem where every time I edit two models in one form, and hit the Update button, I get the error :
No route matches "/obligation/update" with {:method=>:post}

I have 2 models : obligation and assignment.

obligation has_many :assignments and assignment belongs_to :obligation

I have changed the update def code and modified the edit file but dont know why it is not working out.

Please help me out with it!

Hi Ryan,

Just wanted to extend a huge thank you. I'm just beginning with rails and this tutorials you've made about forms were just what I needed. Again, Thank You!

This is a great tutorial and thanks to a new gem, ActivePresenter, things are looking a lot easier for working with multiple models in a single form.

http://jamesgolick.com/2008/7/28/introd … ready-know

Lots of the logic and RJS that Ryan describes could easily be modified to work with ActivePresenter as well.  It doesn't support building multiple child model records yet but that will soon be supported (which is a major point of this tutorial).  But the promise is there.

Last edited by MDWeezer (2008-08-12 09:31:52)