Problems with accepts_nested_attributes_for

rubyonrails-talk
1

Hopefully someone can help. I have the following models

class Parent < ActiveRecord::Base

schema id int, name string

has_many :children accepts_nested_attributes_for :children end

class Child < ActiveRecord::Base

schema id int, name string, parent_id int

belongs_to :parent end

… the following view …

New parent

<% form_for :parent, :url => { :action => :create } do |p| %> <%= p.text_field :name %>
<% p.fields_for :children do |c| %> <%= c.text_field :name %> <% end %>

<%= p.submit ‘Create’ %>

<% end %>

… and a scaffold built parents_controller …

GET /parents/new

GET /parents/new.xml

def new @parent = Parent.new

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

end

POST /parents

POST /parents.xml

def create @parent = Parent.new(params[:parent])

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

end

I’m getting this error …

2

Hi Anthony,

It looks like your form_for line in your view is wrong... try this:   <% form_for(@parent) do |p| %>

...instead of this:   <% form_for :parent, :url => { :action => :create } do |p| %>

For some reason the way you called form_for isn't compatible with the nested attributes feature, and so your form's HTML didn't contain the proper name for the child field name="parent[children_attributes][0] [name]". Also, I added a line to your controller to create a single new child when creating a new parent form; otherwise the child name field won’t appear:

def new     @parent = Parent.new     @parent.children.build

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

It should work exactly the same way with the has_many, :through association. Hope this helps!

- pat

3

Cool. Thanks, Pat.

Have just implemented that and it works fine … even with :through.

Nice.

-Ants