Rails magic form helper – create field based on type

# put this in lib/magic_form.rb
class MagicForm < ActionView::Helpers::FormBuilder
  def input_fields(opts = {})
    object = @object.class
    columns = object.columns.delete_if {|key,value| opts[:exclude] && opts[:exclude].include?(key.name) || key.name == "id" }
    columns.collect {|o| input_for(o.name)}
  end
 
  def input_for(field, opts = {})
    field = field.to_s
    field_label = self.label(field, opts[:label])
    type = @object.class.columns_hash[field].type.to_s
 
    if field.include?("_id")
      field = self.collection_select field, field.gsub("_id","").camelize.constantize.all, opts[:option_id] ? opts[:options_id] : :id, opts[:option_label] ? opts[:option_label] : :name
    else
      field = case type
        when "string", "integer", "float"
          self.text_field field, opts
        when "boolean"
          self.check_box field, opts
        when "datetime"
          self.datetime_select field, opts
        when "date"
          self.date_select field, opts
        when "time"
          self.time_select field, opts
        when "text"
          self.text_area field, opts
        when "binary"
          self.file_field field, opts
        eles
          self.text_field field, opts
        end
    end
 
    if type == "boolean"
      "<p>\n\t#{field}\n\t#{field_label}\n</p>\n"
    else
      "<p>\n\t#{field_label}\n\t<br />\n\t#{field}\n</p>\n"
    end
  end
end
 
# Example usage
# app/admin/views/listings/new.html.haml
%h2 New listing
= render :partial => "form", :locals =&gt; {:listing => @listing}
 
# app/models/listing.rb
class Listing < ActiveRecord::Base
  has_one :status
end
 
# app/models/status.rb
class Status < ActiveRecord::Base
  validates_presence_of :name
  belongs_to :listing
end
 
# app/admin/views/llistings/_form.html.haml
# single field usage
# f.input_for :price prints out the label along with the proper field. integer, string, float is a
# text field, text is a text area, boolean is a checkbox, date field is a date selector, datetime
# is date time selector, etc.
# f.input_for :status_id makes a label with a select field and populates the select input
# with all of the options from the status table.  The way that the helper determines the
# associated model's data could probably be improved upon, I'm sure there's a better way.
- form_for ([:admin, @listing]), :builder =&gt; MagicForm  do |f|
  = f.input_for :price
  = f.input_for :status_id
  = submit_tag "Create new listing"
 
# app/admin/views/listings/_form.html.haml
# complete form maker
# f.input_fields will make the entire form for you from Model.columns (excluding id, didn't
# want to use content_columns since that strips out all fields that have _id).  This probably
# won't be used much but it's here for really basic models where nothing too complicated is going on.
- form_for ([:admin, @listing]), :builder => MagicForm  do |f|
  = f.input_fields, :exclude => ['created_at']
  = submit_tag "Create new listing"
 
# the helper doesn't support has_many associations just has_one associations.
# This is meant to be used as a replacement for most of the simple cases for
# administering content, not for complex forms or associations.