ActiveRecord::ColumnMetadata
Store metadata about columns in the database, as comments on columns (advanced PostgreSQL feature)
Installation
Add this line to your application's Gemfile:
gem 'activerecord-column_metadata'
And then execute:
$ bundle
Or install it yourself as:
$ gem install activerecord-column_metadata
Usage
In a migration:
create_table(:cars) do |t|
t.string :name
t.string :manufacturer
t.string :model
t.boolean :4wd
t.boolean :abs
t.boolean :airbag
t.boolean :gps
t.boolean :music_player
[:4wd, :abs, :airbag, :gps, :music_player].each do |extra|
t.column_metadata(extra, {extra: true})
end
end
or
add_column :cars, :aircondition, :boolean, metadata: {extra: true}
And then you can say in the model:
class Car < ActiveRecord::Base
def self.extras
ActiveRecord::ColumnMetadata.to_a("cars").select do |arr|
column_name, metadata = arr
column_name if metadata["extra"] == true
end
end
end
Rationale
In the above example you could hardcode extras in the model:
class Car < ActiveRecord::Base
def self.extras
[:4wd, :abs, :airbag, :gps, :music_player]
end
end
But what will happen when you have to add or remove an extra? You have to edit two files: migration and the corresponding ActiveRecord model. Unnecessary repetition causes brain injury.
Contributing
- Fork it
- Create your feature branch (
git checkout -b my-new-feature) - Commit your changes (
git commit -am 'Add some feature') - Push to the branch (
git push origin my-new-feature) - Create new Pull Request