vendor/plugins/has_many_polymorphs/lib/has_many_polymorphs/base.rb

   1
   2 module ActiveRecord
   3   class Base
   4
   5     class << self
   6
   7       # Interprets a polymorphic row from a unified SELECT, returning the appropriate ActiveRecord instance. Overrides ActiveRecord::Base.instantiate_without_callbacks.
   8       def instantiate_with_polymorphic_checks(record)
   9         if record['polymorphic_parent_class']
  10           reflection = record['polymorphic_parent_class'].constantize.reflect_on_association(record['polymorphic_association_id'].to_sym)
  11 #          _logger_debug "Instantiating a polymorphic row for #{record['polymorphic_parent_class']}.reflect_on_association(:#{record['polymorphic_association_id']})"
  12
  13           # rewrite the record with the right column names
  14           table_aliases = reflection.options[:table_aliases].dup
  15           record = Hash[*table_aliases.keys.map {|key| [key, record[table_aliases[key]]] }.flatten]
  16
  17           # find the real child class
  18           klass = record["#{self.table_name}.#{reflection.options[:polymorphic_type_key]}"].constantize
  19           if sti_klass = record["#{klass.table_name}.#{klass.inheritance_column}"]
  20             klass = klass.class_eval do compute_type(sti_klass) end # in case of namespaced STI models
  21           end
  22
  23           # check that the join actually joined to something
  24           unless (child_id = record["#{self.table_name}.#{reflection.options[:polymorphic_key]}"]) == record["#{klass.table_name}.#{klass.primary_key}"]
  25             raise ActiveRecord::Associations::PolymorphicError,
  26               "Referential integrity violation; child <#{klass.name}:#{child_id}> was not found for #{reflection.name.inspect}"
  27           end
  28
  29           # eject the join keys
  30           # XXX not very readable
  31           record = Hash[*record._select do |column, value|
  32             column[/^#{klass.table_name}/]
  33           end.map do |column, value|
  34             [column[/\.(.*)/, 1], value]
  35           end.flatten]
  36
  37           # allocate and assign values
  38           returning(klass.allocate) do |obj|
  39             obj.instance_variable_set("@attributes", record)
  40             obj.instance_variable_set("@attributes_cache", Hash.new)
  41
  42             if obj.respond_to_without_attributes?(:after_find)
  43               obj.send(:callback, :after_find)
  44             end
  45
  46             if obj.respond_to_without_attributes?(:after_initialize)
  47               obj.send(:callback, :after_initialize)
  48             end
  49
  50           end
  51         else
  52           instantiate_without_polymorphic_checks(record)
  53         end
  54       end
  55
  56       alias_method_chain :instantiate, :polymorphic_checks
  57     end
  58
  59   end
  60 end