Module: ActiveRecord::Reflection::ClassMethods

Defined in:
activerecord/lib/active_record/reflection.rb

Overview

Reflection enables the ability to examine the associations and aggregations of Active Record classes and objects. This information, for example, can be used in a form builder that takes an Active Record object and creates input fields for all of the attributes depending on their type and displays the associations to other objects.

MacroReflection class has info for AggregateReflection and AssociationReflection classes.

Instance Method Summary collapse

Instance Method Details

#_reflect_on_association(association) ⇒ Object

:nodoc:


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# File 'activerecord/lib/active_record/reflection.rb', line 119

def _reflect_on_association(association) # :nodoc:
  _reflections[association.to_s]
end

#clear_reflections_cacheObject

:nodoc:


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# File 'activerecord/lib/active_record/reflection.rb', line 128

def clear_reflections_cache # :nodoc:
  @__reflections = nil
end

#reflect_on_aggregation(aggregation) ⇒ Object

Returns the AggregateReflection object for the named aggregation (use the symbol).

Account.reflect_on_aggregation(:balance) # => the balance AggregateReflection

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# File 'activerecord/lib/active_record/reflection.rb', line 67

def reflect_on_aggregation(aggregation)
  aggregate_reflections[aggregation.to_s]
end

#reflect_on_all_aggregationsObject

Returns an array of AggregateReflection objects for all the aggregations in the class.


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# File 'activerecord/lib/active_record/reflection.rb', line 59

def reflect_on_all_aggregations
  aggregate_reflections.values
end

#reflect_on_all_associations(macro = nil) ⇒ Object

Returns an array of AssociationReflection objects for all the associations in the class. If you only want to reflect on a certain association type, pass in the symbol (:has_many, :has_one, :belongs_to) as the first parameter.

Example:

Account.reflect_on_all_associations             # returns an array of all associations
Account.reflect_on_all_associations(:has_many)  # returns an array of all has_many associations

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# File 'activerecord/lib/active_record/reflection.rb', line 104

def reflect_on_all_associations(macro = nil)
  association_reflections = reflections.values
  association_reflections.select! { |reflection| reflection.macro == macro } if macro
  association_reflections
end

#reflect_on_all_autosave_associationsObject

Returns an array of AssociationReflection objects for all associations which have :autosave enabled.


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# File 'activerecord/lib/active_record/reflection.rb', line 124

def reflect_on_all_autosave_associations
  reflections.values.select { |reflection| reflection.options[:autosave] }
end

#reflect_on_association(association) ⇒ Object

Returns the AssociationReflection object for the association (use the symbol).

Account.reflect_on_association(:owner)             # returns the owner AssociationReflection
Invoice.reflect_on_association(:line_items).macro  # returns :has_many

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# File 'activerecord/lib/active_record/reflection.rb', line 115

def reflect_on_association(association)
  reflections[association.to_s]
end

#reflectionsObject

Returns a Hash of name of the reflection as the key and an AssociationReflection as the value.

Account.reflections # => {"balance" => AggregateReflection}

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# File 'activerecord/lib/active_record/reflection.rb', line 75

def reflections
  @__reflections ||= begin
    ref = {}

    _reflections.each do |name, reflection|
      parent_reflection = reflection.parent_reflection

      if parent_reflection
        parent_name = parent_reflection.name
        ref[parent_name.to_s] = parent_reflection
      else
        ref[name] = reflection
      end
    end

    ref
  end
end