acts_as_list helper

February 25th, 2008 • Uncategorized

# include this in application.rb
# or only in the controllers you need it.
# USAGE
# class FooParents::FoosController < ApplicationController
#   include ActsAsListHelper
#   protected
#   def load_foo_parent
#     @foo_parent = FooParent.find(params[:foo_parent_id])
#   end
#   public
#   def create
#     @foo = @foo_parent.foos.build(params[:foo])
#     if @foo.save
#       update_positions :foo_parent, :foo
#       # ...
#     else
#       # ...
#     end
#   end
#   def update
#     @foo = @foo_parent.foos.find(params[:id])
#     update_positions :foo_parent, :foo
#     if @foo.save
#       # ...
#     else
#       # ...
#     end
#   end
#   #...
# end

module ActsAsListHelper
  # support acts_as_list
  def update_positions(parent_name, resource_name)
    parent = instance_variable_get("@#{parent_name.to_s}")
    resource = instance_variable_get("@#{resource_name.to_s}")

    desired_position = params[resource_name.to_sym][:position].to_i
    nr_of_nested_resources = parent.send(resource_name.to_s.pluralize).size

    if desired_position > nr_of_nested_resources + 1 || desired_position < 1
      # correct values that are out of list bounds
      position = nr_of_nested_resources + 1
    else
      position = desired_position
    end
    # acts_as_list call
    resource.insert_at(position)
  end
end

Tags: rails, rails controller, rails models

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