### Home Classes Methods

### In Files

- lib/active_record/reflection.rb

### Methods

- #create_reflection
- #reflect_on_aggregation
- #reflect_on_all_aggregations
- #reflect_on_all_associations
- #reflect_on_all_autosave_associations
- #reflect_on_association

### Files

- README.rdoc

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No matching classes.

# ActiveRecord::Reflection::ClassMethods

Reflection enables to interrogate Active Record classes and objects about their associations and aggregations. This information can, for example, 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.

### Public Instance Methods

create_reflection(macro, name, options, active_record) click to toggle source

    # File lib/active_record/reflection.rb, line 23
    def create_reflection(macro, name, options, active_record)
      case macro
        when :has_many, :belongs_to, :has_one, :has_and_belongs_to_many
          klass = options[:through] ? ThroughReflection : AssociationReflection
          reflection = klass.new(macro, name, options, active_record)
        when :composed_of
          reflection = AggregateReflection.new(macro, name, options, active_record)
      end

      self.reflections = self.reflections.merge(name => reflection)
      reflection
    end

reflect_on_aggregation(aggregation) click to toggle source

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

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

    # File lib/active_record/reflection.rb, line 45
    def reflect_on_aggregation(aggregation)
      reflections[aggregation].is_a?(AggregateReflection) ? reflections[aggregation] : nil
    end

reflect_on_all_aggregations() click to toggle source

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

    # File lib/active_record/reflection.rb, line 37
    def reflect_on_all_aggregations
      reflections.values.grep(AggregateReflection)
    end

reflect_on_all_associations(macro = nil) click to toggle source

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

    # File lib/active_record/reflection.rb, line 59
    def reflect_on_all_associations(macro = nil)
      association_reflections = reflections.values.grep(AssociationReflection)
      macro ? association_reflections.select { |reflection| reflection.macro == macro } : association_reflections
    end

reflect_on_all_autosave_associations() click to toggle source

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

    # File lib/active_record/reflection.rb, line 74
    def reflect_on_all_autosave_associations
      reflections.values.select { |reflection| reflection.options[:autosave] }
    end

reflect_on_association(association) click to toggle source

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

    # File lib/active_record/reflection.rb, line 69
    def reflect_on_association(association)
      reflections[association].is_a?(AssociationReflection) ? reflections[association] : nil
    end

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