duplicate f.fields_for in edit action - ruby-on-rails

Question

Controller: projects_controller.rb
def new
#project = Project.new
#project.repositories.build
end
def edit
#project = Project.find(params[:id])
end
Model: project_sub_type.rb
class ProjectSubType < ActiveRecord::Base
has_many :repositories, :dependent => :destroy
accepts_nested_attributes_for :repositories
end
View: _form.html.erb
<%= form_for #project, :html => {:class => 'project'} do |f| %>
<%= f.label :name, "Project name" %>
<%= f.text_field :name %>
<%= f.fields_for :repositories do |ff| %>
<%= ff.check_box :repos_name, {} , "svn_software", nil %> Svn Software
<% end %>
<%= f.fields_for :repositories do |ff| %>
<%= ff.check_box :repos_name, {} , "git_software", nil %> Git Software
<% end %>
<%= f.submit "Save"%>
edit.html.erb
<h2>Edit project</h2>
<%= render 'form' %>
Question: During create it creates the checkbox like this
<input type="checkbox" value="svn_software" name="project[repositories_attributes][0][repos_name]" id="project_repositories_attributes_0_repos_name">
<input type="checkbox" value="git_software" name="project[repositories_attributes][1][repos_name]" id="project_repositories_attributes_1_repos_name">
And it works perfectly for me. But during edit it creates 2 fields extra:
<input type="checkbox" value="svn_software" name="project[repositories_attributes][0][repos_name]" id="project_repositories_attributes_0_repos_name">
<input type="checkbox" value="svn_software" name="project[repositories_attributes][1][repos_name]" id="project_repositories_attributes_1_repos_name">
<input type="checkbox" value="git_software" name="project[repositories_attributes][2][repos_name]" id="project_repositories_attributes_2_repos_name">
<input type="checkbox" value="git_software" name="project[repositories_attributes][3][repos_name]" id="project_repositories_attributes_3_repos_name">
And also creates a hidden field as below:
<input type="hidden" value="51" name="project[repositories_attributes][0][id]" id="project_repositories_attributes_0_id">
to .. 3
Can someone please point out my mistake. And the same problem exist if I use 1 fields_for and loop though an array.
Can anyone please help.
Thanks in advance

Answer 1

Reference to http://apidock.com/rails/v3.2.13/ActionView/Helpers/FormHelper/fields_for
Your code will cause duplication result, because The block given to the nested fields_for call will be repeated for each instance in the collection, so you have to :
<%= form_for #project, :html => {:class => 'project'} do |f| %>
<%= f.label :name, "Project name" %>
<%= f.text_field :name %>
<% #project.repositories.each do |r| %>
<%= f.fields_for :repositories, r do |ff| %>
<%= ff.check_box :repos_name, {} , r.repos_name, true %><%=r.repos_name%>
<% end %>
<% end %>
<%= f.submit "Save"%>
But when create, you should fill the check_box not include in repositories.
So you could:
<%= form_for #project, :html => {:class => 'project'} do |f| %>
<%= f.label :name, "Project name" %>
<%= f.text_field :name %>
<% #project.repositories.each do |r| %>
<%= f.fields_for :repositories, r do |ff| %>
<%= ff.check_box :repos_name, {} , r.repos_name, true %><%=r.repos_name%>
<% end %>
<% end %>
<% (['svn_software','git_software'] - #project.repositories.map(& :repos_name)).each do |name| %>
<%= ff.check_box :repos_name, {} , name, nil %><%=name%>
<% end %>
<%= f.submit "Save"%>