How to initialise a nested input field with ruby on rails? - ruby-on-rails

Question

I am creating a hierarchical list of values (id, code, name, parent_id) for which the code is the business key. This means that when a user wants to attach a value to a parent, he fills in a parent_code field, and before save the model associates the parent value id. The value.rb model has a virtual attribute: parent_code, and the following before_save action:
class Value < ActiveRecord::Base
extend CsvHelper
# This virtual attribute allows user to ignore parent value id
attr_accessor :parent_code
### scope
# Value is linked to a list which belongs to the correct scope
### before filter
before_save :set_parent_id # user only inputs parent code
### validation
validates :code, presence: true
validates :name, presence: true
belongs_to :values_list
has_many :subs, :class_name => "Value", :foreign_key => :parent_id
belongs_to :superior, :class_name => "Value", :foreign_key => :parent_id
### private functions definitions
private
### before filters
def set_parent_id
self.level = 1
if not self.parent_code.blank?
#parent = Value.where("code = ? and values_list_id = ?", self.parent_code, self.values_list_id).first
self.parent_id = #parent.id
self.level = #parent.level.next
end
end
end
This model is used as nested object of a values_list model. This works fine at creation, and produces the expected result.
But when editing a record, the parent_code attribute is by no way initialized, and thus now shown in the input field. Here is the nested form:
<table class="table table-striped table-condensed">
<tr align="left">
<th></th>
<% if #values_list.is_hierarchical %>
<th> <%= t('ParentCode') %> </th>
<th> <%= t('Level') %> </th>
<% end %>
<th> <%= t('Code') %> </th>
<th> <%= t('Value') %> </th>
<th> <%= t('Description') %> </th>
</tr>
<%= f.nested_fields_for :values, #values_list.values.order(:code), wrapper_tag: 'tr' do |value| %>
<td><%= value.remove_nested_fields_link {image_tag("remove.png")} %></td>
<% if #values_list.is_hierarchical %>
<td><%= value.text_field :parent_code, ***# code to initialise #*** %> </td>
<td><%= value.text_field :level, disabled: true %> </td>
<% end %>
<td><%= value.text_field :code %> </td>
<td><%= value.text_field :name %> </td>
<td><%= value.text_field :description %> </td>
<% end %>
</table>
How can I initialise the input field with myvalue.superior.code ?
Thanks a lot!

Answer 1

You could access the form object that you're using in your f.nested_fields_for and set the value that way probably.
<%= f.nested_fields_for :values, #values_list.values.order(:code), wrapper_tag: 'tr' do |value| %>
...
<td><%= value.text_field :parent_code, value: value.object.superior.code %> </td>
<td><%= value.text_field :level, disabled: true %> </td>
...