Hashdown
Hashdown is a super lightweight rails plugin that adds hash-style lookups and option lists (for generating dropdowns) to ActiveRecord models. Note: Hashdown has been updated to support Rails 3. If you're looking for the original plugin version, it's in the rails 2 branch
Installation
Add this line to your application's Gemfile:
gem 'hashdown'
And then execute:
$ bundle
Or install it yourself as:
$ gem install hashdown
Usage
Given the following class definition:
class State < ActiveRecord::Base
finder :abbreviation
end
You can look up states via their abbreviations like so:
@colorado = State[:CO]
By default, calling the finder method with a token that does not exist in the database will result in an ActiveRecord::RecordNotFound exception being thrown. This can be overridden by adding a :default option to your finder declaration.
class PurchaseOrder < ActiveRecord::Base
finder :number, :default => nil
end
In this case, PurchaseOrder['00734'] will silently return nil if that number is not found.
These types of reference data models are often something you need to populate a select list on your form, so hashdown includes a method to generate your option list:
-
Declare your model to be selectable:
class State < ActiveRecord::Base selectable end
-
Call select_options in your form to return a set of name, value pairs to pass into a select builder:
<%= form.select :state_id, State.select_options %>
By default, selectable will return the :id of the record as the value, and the :name attribute value as the display. This can be overridden inline in the select_options call:
State.select_options(:name, :abbreviation)
The grouped_options_for_select format is also supported:
State.select_options(:group => :region)
Adding finder and selectable to a model is roughly equivalent to the following implementation:
class State < ActiveRecord::Base
validates_uniqueness_of :abbreviation
def self.[](state_code)
where(abbreviation: state_code).first
end
def self.select_options
all.map{|s| [s.name, s.id] }
end
end
...except hashdown adds configuration for flexibility and caching for speedy lookups.
Contributing
- Fork it
- Create your feature branch (
git checkout -b my-new-feature
) - Commit your changes (
git commit -am 'Added some feature'
) - Push to the branch (
git push origin my-new-feature
) - Create new Pull Request