321 lines
12 KiB
Ruby
321 lines
12 KiB
Ruby
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module ActiveRecord
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module Reflection # :nodoc:
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def self.included(base)
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base.extend(ClassMethods)
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end
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# Reflection allows you to interrogate Active Record classes and objects about their associations and aggregations.
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# This information can, for example, be used in a form builder that took an Active Record object and created input
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# fields for all of the attributes depending on their type and displayed the associations to other objects.
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#
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# You can find the interface for the AggregateReflection and AssociationReflection classes in the abstract MacroReflection class.
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module ClassMethods
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def create_reflection(macro, name, options, active_record)
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case macro
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when :has_many, :belongs_to, :has_one, :has_and_belongs_to_many
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klass = options[:through] ? ThroughReflection : AssociationReflection
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reflection = klass.new(macro, name, options, active_record)
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when :composed_of
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reflection = AggregateReflection.new(macro, name, options, active_record)
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end
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write_inheritable_hash :reflections, name => reflection
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reflection
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end
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# Returns a hash containing all AssociationReflection objects for the current class
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# Example:
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#
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# Invoice.reflections
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# Account.reflections
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#
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def reflections
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read_inheritable_attribute(:reflections) || write_inheritable_attribute(:reflections, {})
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end
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# Returns an array of AggregateReflection objects for all the aggregations in the class.
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def reflect_on_all_aggregations
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reflections.values.select { |reflection| reflection.is_a?(AggregateReflection) }
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end
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# Returns the AggregateReflection object for the named +aggregation+ (use the symbol). Example:
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#
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# Account.reflect_on_aggregation(:balance) # returns the balance AggregateReflection
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#
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def reflect_on_aggregation(aggregation)
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reflections[aggregation].is_a?(AggregateReflection) ? reflections[aggregation] : nil
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end
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# Returns an array of AssociationReflection objects for all the associations in the class. If you only want to reflect on a
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# certain association type, pass in the symbol (<tt>:has_many</tt>, <tt>:has_one</tt>, <tt>:belongs_to</tt>) for that as the first parameter.
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# Example:
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#
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# Account.reflect_on_all_associations # returns an array of all associations
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# Account.reflect_on_all_associations(:has_many) # returns an array of all has_many associations
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#
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def reflect_on_all_associations(macro = nil)
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association_reflections = reflections.values.select { |reflection| reflection.is_a?(AssociationReflection) }
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macro ? association_reflections.select { |reflection| reflection.macro == macro } : association_reflections
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end
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# Returns the AssociationReflection object for the named +association+ (use the symbol). Example:
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#
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# Account.reflect_on_association(:owner) # returns the owner AssociationReflection
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# Invoice.reflect_on_association(:line_items).macro # returns :has_many
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#
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def reflect_on_association(association)
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reflections[association].is_a?(AssociationReflection) ? reflections[association] : nil
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end
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# Returns an array of AssociationReflection objects for all associations which have <tt>:autosave</tt> enabled.
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def reflect_on_all_autosave_associations
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reflections.values.select { |reflection| reflection.options[:autosave] }
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end
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end
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# Abstract base class for AggregateReflection and AssociationReflection that describes the interface available for both of
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# those classes. Objects of AggregateReflection and AssociationReflection are returned by the Reflection::ClassMethods.
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class MacroReflection
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attr_reader :active_record
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def initialize(macro, name, options, active_record)
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@macro, @name, @options, @active_record = macro, name, options, active_record
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end
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# Returns the name of the macro. For example, <tt>composed_of :balance, :class_name => 'Money'</tt> will return
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# <tt>:balance</tt> or for <tt>has_many :clients</tt> it will return <tt>:clients</tt>.
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def name
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@name
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end
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# Returns the macro type. For example, <tt>composed_of :balance, :class_name => 'Money'</tt> will return <tt>:composed_of</tt>
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# or for <tt>has_many :clients</tt> will return <tt>:has_many</tt>.
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def macro
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@macro
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end
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# Returns the hash of options used for the macro. For example, it would return <tt>{ :class_name => "Money" }</tt> for
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# <tt>composed_of :balance, :class_name => 'Money'</tt> or +{}+ for <tt>has_many :clients</tt>.
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def options
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@options
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end
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# Returns the class for the macro. For example, <tt>composed_of :balance, :class_name => 'Money'</tt> returns the Money
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# class and <tt>has_many :clients</tt> returns the Client class.
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def klass
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@klass ||= class_name.constantize
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end
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# Returns the class name for the macro. For example, <tt>composed_of :balance, :class_name => 'Money'</tt> returns <tt>'Money'</tt>
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# and <tt>has_many :clients</tt> returns <tt>'Client'</tt>.
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def class_name
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@class_name ||= options[:class_name] || derive_class_name
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end
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# Returns +true+ if +self+ and +other_aggregation+ have the same +name+ attribute, +active_record+ attribute,
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# and +other_aggregation+ has an options hash assigned to it.
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def ==(other_aggregation)
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other_aggregation.kind_of?(self.class) && name == other_aggregation.name && other_aggregation.options && active_record == other_aggregation.active_record
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end
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def sanitized_conditions #:nodoc:
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@sanitized_conditions ||= klass.send(:sanitize_sql, options[:conditions]) if options[:conditions]
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end
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# Returns +true+ if +self+ is a +belongs_to+ reflection.
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def belongs_to?
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macro == :belongs_to
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end
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private
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def derive_class_name
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name.to_s.camelize
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end
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end
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# Holds all the meta-data about an aggregation as it was specified in the Active Record class.
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class AggregateReflection < MacroReflection #:nodoc:
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end
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# Holds all the meta-data about an association as it was specified in the Active Record class.
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class AssociationReflection < MacroReflection #:nodoc:
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# Returns the target association's class:
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#
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# class Author < ActiveRecord::Base
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# has_many :books
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# end
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#
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# Author.reflect_on_association(:books).klass
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# # => Book
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#
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# <b>Note:</b> do not call +klass.new+ or +klass.create+ to instantiate
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# a new association object. Use +build_association+ or +create_association+
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# instead. This allows plugins to hook into association object creation.
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def klass
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@klass ||= active_record.send(:compute_type, class_name)
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end
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# Returns a new, unsaved instance of the associated class. +options+ will
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# be passed to the class's constructor.
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def build_association(*options)
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klass.new(*options)
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end
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# Creates a new instance of the associated class, and immediates saves it
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# with ActiveRecord::Base#save. +options+ will be passed to the class's
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# creation method. Returns the newly created object.
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def create_association(*options)
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klass.create(*options)
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end
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# Creates a new instance of the associated class, and immediates saves it
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# with ActiveRecord::Base#save!. +options+ will be passed to the class's
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# creation method. If the created record doesn't pass validations, then an
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# exception will be raised.
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#
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# Returns the newly created object.
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def create_association!(*options)
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klass.create!(*options)
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end
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def table_name
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@table_name ||= klass.table_name
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end
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def quoted_table_name
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@quoted_table_name ||= klass.quoted_table_name
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end
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def primary_key_name
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@primary_key_name ||= options[:foreign_key] || derive_primary_key_name
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end
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def association_foreign_key
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@association_foreign_key ||= @options[:association_foreign_key] || class_name.foreign_key
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end
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def counter_cache_column
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if options[:counter_cache] == true
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"#{active_record.name.demodulize.underscore.pluralize}_count"
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elsif options[:counter_cache]
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options[:counter_cache]
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end
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end
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def columns(tbl_name, log_msg)
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@columns ||= klass.connection.columns(tbl_name, log_msg)
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end
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def reset_column_information
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@columns = nil
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end
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def check_validity!
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end
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def through_reflection
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false
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end
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def through_reflection_primary_key_name
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end
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def source_reflection
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nil
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end
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private
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def derive_class_name
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class_name = name.to_s.camelize
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class_name = class_name.singularize if [ :has_many, :has_and_belongs_to_many ].include?(macro)
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class_name
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end
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def derive_primary_key_name
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if belongs_to?
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"#{name}_id"
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elsif options[:as]
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"#{options[:as]}_id"
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else
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active_record.name.foreign_key
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end
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end
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end
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# Holds all the meta-data about a :through association as it was specified in the Active Record class.
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class ThroughReflection < AssociationReflection #:nodoc:
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# Gets the source of the through reflection. It checks both a singularized and pluralized form for <tt>:belongs_to</tt> or <tt>:has_many</tt>.
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# (The <tt>:tags</tt> association on Tagging below.)
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#
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# class Post < ActiveRecord::Base
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# has_many :taggings
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# has_many :tags, :through => :taggings
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# end
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#
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def source_reflection
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@source_reflection ||= source_reflection_names.collect { |name| through_reflection.klass.reflect_on_association(name) }.compact.first
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end
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# Returns the AssociationReflection object specified in the <tt>:through</tt> option
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# of a HasManyThrough or HasOneThrough association. Example:
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#
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# class Post < ActiveRecord::Base
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# has_many :taggings
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# has_many :tags, :through => :taggings
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# end
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#
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# tags_reflection = Post.reflect_on_association(:tags)
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# taggings_reflection = tags_reflection.through_reflection
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#
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def through_reflection
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@through_reflection ||= active_record.reflect_on_association(options[:through])
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end
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# Gets an array of possible <tt>:through</tt> source reflection names:
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#
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# [:singularized, :pluralized]
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#
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def source_reflection_names
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@source_reflection_names ||= (options[:source] ? [options[:source]] : [name.to_s.singularize, name]).collect { |n| n.to_sym }
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end
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def check_validity!
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if through_reflection.nil?
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raise HasManyThroughAssociationNotFoundError.new(active_record.name, self)
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end
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if source_reflection.nil?
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raise HasManyThroughSourceAssociationNotFoundError.new(self)
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end
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if options[:source_type] && source_reflection.options[:polymorphic].nil?
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raise HasManyThroughAssociationPointlessSourceTypeError.new(active_record.name, self, source_reflection)
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end
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if source_reflection.options[:polymorphic] && options[:source_type].nil?
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raise HasManyThroughAssociationPolymorphicError.new(active_record.name, self, source_reflection)
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end
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unless [:belongs_to, :has_many, :has_one].include?(source_reflection.macro) && source_reflection.options[:through].nil?
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raise HasManyThroughSourceAssociationMacroError.new(self)
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end
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end
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def through_reflection_primary_key
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through_reflection.belongs_to? ? through_reflection.klass.primary_key : through_reflection.primary_key_name
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end
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def through_reflection_primary_key_name
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through_reflection.primary_key_name if through_reflection.belongs_to?
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end
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private
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def derive_class_name
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# get the class_name of the belongs_to association of the through reflection
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options[:source_type] || source_reflection.class_name
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end
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end
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end
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end
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