define_columns

Define Columns allows you to manipulate the content columns of your ActiveRecord model.

Features

Add virtual attributes as columns
Hiding existing content columns
Changes the output of the column

Benefits

Allows you to place your logic in the model instead of the view.
Does not assume your table markup. You have full flexibility to change things
No need to hand write the table columns for virtual attributes

Installation

$ gem install define_columns

Usage

# Person has content_columns [ "name", "address", "gender", "hobbies" ]
# Note that the names must be an exact match
class Person < ActiveRecord::Base
  define_columns do |columns|
    columns.hide %w(name)			# takes in an array of column names
    columns.add %w(favourite_color) 		# can add virtual attributes as columns
    columns.show(:gender) do |gender|	# returns "-Male-" for column.show(person)
      "-#{gender}-"       			     
    end
  end  

  def favourite_color
    red
  end  
end

# Person.table_columns returns [ "address", "gender", "hobbies", "favourite_color" ]

# In your view(in haml)
 %table
   %thead
     %tr
       - Person.table_columns.each do |column|
         %th= column.header

   - @persons.each do |person|
     %tbody

- Person.table_columns.each do |column|

%td= column.show(person)

To Note

The show block takes in an argument and a block.

columns.show(:gender) do |gender|	
  "-#{gender}-"       			     
end

The argument :gender must match the column name. The block parameter ‘gender’ is equivalent to the result of @person.gender.