diff options
Diffstat (limited to 'activerecord/lib')
| -rw-r--r-- | activerecord/lib/active_record/inheritance.rb | 48 | ||||
| -rw-r--r-- | activerecord/lib/active_record/persistence.rb | 26 |
2 files changed, 50 insertions, 24 deletions
diff --git a/activerecord/lib/active_record/inheritance.rb b/activerecord/lib/active_record/inheritance.rb index 850911ebe7..6ab67fdece 100644 --- a/activerecord/lib/active_record/inheritance.rb +++ b/activerecord/lib/active_record/inheritance.rb @@ -92,15 +92,6 @@ module ActiveRecord store_full_sti_class ? name : name.demodulize end - # Finder methods must instantiate through this method to work with the - # single-table inheritance model that makes it possible to create - # objects of different types from the same table. - def instantiate(record, column_types = {}) - sti_class = find_sti_class(record[inheritance_column]) - column_types = sti_class.decorate_columns(column_types) - sti_class.allocate.init_with('attributes' => record, 'column_types' => column_types) - end - protected # Returns the class type of the record using the current module as a prefix. So descendants of @@ -132,24 +123,33 @@ module ActiveRecord private + # Called by +instantiate+ to decide which class to use for a new + # record instance. For single-table inheritance, we check the record + # for a +type+ column and return the corresponding class. + def discriminate_class_for_record(record) + if using_single_table_inheritance?(record) + find_sti_class(record[inheritance_column]) + else + super + end + end + + def using_single_table_inheritance?(record) + record[inheritance_column].present? && columns_hash.include?(inheritance_column) + end + def find_sti_class(type_name) - if type_name.blank? || !columns_hash.include?(inheritance_column) - self + if store_full_sti_class + ActiveSupport::Dependencies.constantize(type_name) else - begin - if store_full_sti_class - ActiveSupport::Dependencies.constantize(type_name) - else - compute_type(type_name) - end - rescue NameError - raise SubclassNotFound, - "The single-table inheritance mechanism failed to locate the subclass: '#{type_name}'. " + - "This error is raised because the column '#{inheritance_column}' is reserved for storing the class in case of inheritance. " + - "Please rename this column if you didn't intend it to be used for storing the inheritance class " + - "or overwrite #{name}.inheritance_column to use another column for that information." - end + compute_type(type_name) end + rescue NameError + raise SubclassNotFound, + "The single-table inheritance mechanism failed to locate the subclass: '#{type_name}'. " + + "This error is raised because the column '#{inheritance_column}' is reserved for storing the class in case of inheritance. " + + "Please rename this column if you didn't intend it to be used for storing the inheritance class " + + "or overwrite #{name}.inheritance_column to use another column for that information." end def type_condition(table = arel_table) diff --git a/activerecord/lib/active_record/persistence.rb b/activerecord/lib/active_record/persistence.rb index 81e56a3e2e..94c109e72b 100644 --- a/activerecord/lib/active_record/persistence.rb +++ b/activerecord/lib/active_record/persistence.rb @@ -38,6 +38,32 @@ module ActiveRecord object end end + + # Given an attributes hash, +instantiate+ returns a new instance of + # the appropriate class. + # + # For example, +Post.all+ may return Comments, Messages, and Emails + # by storing the record's subclass in a +type+ attribute. By calling + # +instantiate+ instead of +new+, finder methods ensure they get new + # instances of the appropriate class for each record. + # + # See +ActiveRecord::Inheritance#discriminate_class_for_record+ to see + # how this "single-table" inheritance mapping is implemented. + def instantiate(record, column_types = {}) + klass = discriminate_class_for_record(record) + column_types = klass.decorate_columns(column_types) + klass.allocate.init_with('attributes' => record, 'column_types' => column_types) + end + + private + # Called by +instantiate+ to decide which class to use for a new + # record instance. + # + # See +ActiveRecord::Inheritance#discriminate_class_for_record+ for + # the single-table inheritance discriminator. + def discriminate_class_for_record(record) + self + end end # Returns true if this object hasn't been saved yet -- that is, a record |