How do I use a single form in a view for a multiple-models in Rails 3?

Question

I have a single form.

That form is currently in the View for the model Message.

Sometimes, I want to be able to associate a Contact (first name, last name) with that particular Message. Contact is its own Model.

When the form is submitted, Message has a contact_id attribute. I would want that contact_id to be associated, but also to create a new Contact.

How do I do that in Rails 3?

rubyprince · Accepted Answer · 2011-03-23 19:21:27Z

2

It seems that you want both Contact and Message objects created from the same form and make them associated. As I told you in a previous question. form_for can take both stand alone values and even other objects values.

_form.html.erb

<% form_for :message do |f| %>
  <%= f.test_field :some_field %>
  ..
  ..
  <%= text_field :contact, :first_name %>
  <%= text_field :contact, :last_name %>
  <%= f.submit %>
<% end %>

messages_controller.rb

def new
  @message = Message.new
  @contact = Contact.new
end

def create
  @message = Message.new(params[:message])
  @contact = Contact.new(params[:contact])
  @contact.message = @message
  if @contact.save # saves both contact and message if has_one relation is given in models
    ..
  else
    ...
  end
end

But this being said, it is better to use Nested form model. For that, you will have to write code centered on contact.

contacts_controller.rb

def new
  @contact = Contact.new
  @contact.message.build
end

def create
  @contact = Contact.new(params[:contact])
  if @contact.save
    ..
  else
    ..
  end
end

_form.html

<% form_for :contact do |f| %>
  <% f.fields_for :message do |p| %>
    <%= p.text_field :some_field %>
    ...
  <% end %>
  <%= f.text_field :first_name %>
  <%= f.text_field :second_name %>
  <%= f.submit %>
<% end %>

For this, you will have to specify accepts_nested_attributes_for :message in Contact.rb

answered Mar 23, 2011 at 19:21

rubyprince

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2 Comments

Satchel Over a year ago

thanks...I wasn't sure whether to nest them since, for example, a contact associated with one message may then be given to someone else in another message...BUT your point if I create the has_one (I assume I would have to pass the message_id attribute to contact_id) I only needed to save @contact is what I'm looking forward ... does that sound right?

rubyprince Over a year ago

yeah..if you have has_one :message in your contact.rb, then when you give @contact.message = @message and you save @contact.save, the contact object and the message object are saved to the database, along with saving contact_id in the message as id of the newly saved contact record. So, you need to do only @contact.save

Pablo B. · Accepted Answer · 2011-03-23 18:15:37Z

0

With a Nested Model Form.

Give a look at: http://asciicasts.com/episodes/196-nested-model-form-part-1

It's based on Rails 2, but there isn't much to be done in order to make the code compatible with Rails 3.

answered Mar 23, 2011 at 18:15

Pablo B.

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