Module: EnumerateBy::Extensions::Associations

Defined in:
lib/enumerate_by/extensions/associations.rb

Overview

Adds a set of helpers for using enumerations in associations, including named scopes and assignment via enumerators.

The examples below assume the following models have been defined:

class Color < ActiveRecord::Base
  enumerate_by :name

  bootstrap(
    {:id => 1, :name => 'red'},
    {:id => 2, :name => 'blue'},
    {:id => 3, :name => 'green'}
  )
end

class Car < ActiveRecord::Base
  belongs_to :color
end

Named scopes

A pair of named scopes are generated for each belongs_to association that is identified by an enumeration. In this case, the following named scopes get generated:

  • with_color / with_colors - Finds all cars with the given color(s)

  • without_color / without_colors - Finds all cars without the given color(s)

For example,

Car.with_color('red')           # Cars with the color name "red"
Car.without_color('red')        # Cars without the color name "red"
Car.with_colors('red', 'blue')  # Cars with either the color names "red" or "blue"

Association assignment

Normally, belongs_to associations are assigned with either the actual record or through its primary key. When used with enumerations, support is added for assigning these associations through the enumerators defined for the class.

For example,

# With valid enumerator
car = Car.new         # => #<Car id: nil, color_id: nil>
car.color = 'red'
car.color_id          # => 1
car.color             # => #<Color id: 1, name: "red">

# With invalid enumerator
car = Car.new         # => #<Car id: nil, color_id: nil>
car.color = 'invalid'
car.color_id          # => nil
car.color             # => nil

In the above example, the actual Color association is automatically looked up by finding the Color record identified by the enumerator the given enumerator (“red” in this case).

Class Method Summary collapse

Instance Method Summary collapse

Class Method Details

.extended(base) ⇒ Object

:nodoc:



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# File 'lib/enumerate_by/extensions/associations.rb', line 61

def self.extended(base) #:nodoc:
  class << base
    alias_method_chain :belongs_to, :enumerations
  end
end

Instance Method Details

#belongs_to_with_enumerations(association_id, options = {}) ⇒ Object

Adds support for belongs_to and enumerations



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# File 'lib/enumerate_by/extensions/associations.rb', line 68

def belongs_to_with_enumerations(association_id, options = {})
  belongs_to_without_enumerations(association_id, options)
  
  # Override accessor if class is valid enumeration
  reflection = reflections[association_id.to_sym]
  if !reflection.options[:polymorphic] && (reflection.klass < ActiveRecord::Base) && reflection.klass.enumeration?
    name = reflection.name
    primary_key_name = reflection.primary_key_name
    class_name = reflection.class_name
    klass = reflection.klass
    
    # Inclusion scopes
    %W(with_#{name} with_#{name.to_s.pluralize}).each do |scope_name|
      named_scope scope_name.to_sym, lambda {|*enumerators| {
        :conditions => {primary_key_name => klass.find_all_by_enumerator!(enumerators).map(&:id)}
      }}
    end
    
    # Exclusion scopes
    %W(without_#{name} without_#{name.to_s.pluralize}).each do |scope_name|
      named_scope scope_name.to_sym, lambda {|*enumerators| {
        :conditions => ["#{primary_key_name} NOT IN (?)", klass.find_all_by_enumerator!(enumerators).map(&:id)]
      }}
    end
    
    # Hook in shortcut writer
    define_method("#{name}_with_enumerators=") do |new_value|
      send("#{name}_without_enumerators=", new_value.is_a?(klass) ? new_value : klass.find_by_enumerator(new_value))
    end
    alias_method_chain "#{name}=", :enumerators
    
    # Track the association
    enumeration_associations[primary_key_name.to_s] = name.to_s
  end
end