How to remove a column from my Rails model ?

Question

I need to remove a few columns from my rails model which i already created and have some row entries in that model. How to do it? Any links which has details for modifying the schema in rails ? I'm using rails version 3.

Answer 1

To remove a database column, you have to generate a migration:

script/rails g migration RemoveColumns

Then in the self.up class method, remove your columns:

def self.up
  remove_column :table_name, :column_name
end

You may want to add them back in the self.down class method as well:

def self.down
  add_column :table_name, :column_name, :type
end

The [Rails Guide][1] for this goes into much more detail.

[1]: http://guides.rubyonrails.org/migrations.html"Rails Guide"