module DuckRecord::Inheritance::ClassMethods
Attributes
Set this to true if this is an abstract class (see abstract_class?
). If you are using inheritance with DuckRecord
and don't want child classes to utilize the implied STI table name of the parent class, this will need to be true. For example, given the following:
class SuperClass < DuckRecord::Base self.abstract_class = true end class Child < SuperClass self.table_name = 'the_table_i_really_want' end
self.abstract_class = true
is required to make Child<.find,.create, or any Arel method>
use the_table_i_really_want
instead of a table called super_classes
Public Instance Methods
Returns whether this class is an abstract class or not.
# File lib/duck_record/inheritance.rb, line 88 def abstract_class? defined?(@abstract_class) && @abstract_class == true end
Returns the class descending directly from DuckRecord::Base
, or an abstract class, if any, in the inheritance hierarchy.
If A extends DuckRecord::Base
, A.base_class will return A. If B descends from A through some arbitrarily deep hierarchy, B.base_class will return A.
If B < A and C < B and if A is an abstract_class
then both B.base_class and C.base_class would return B as the answer since A is an abstract_class.
# File lib/duck_record/inheritance.rb, line 58 def base_class unless self < Base raise DuckRecordError, "#{name} doesn't belong in a hierarchy descending from DuckRecord" end if superclass == Base || superclass.abstract_class? self else superclass.base_class end end
# File lib/duck_record/inheritance.rb, line 92 def inherited(subclass) subclass.instance_variable_set(:@_type_candidates_cache, Concurrent::Map.new) super end
Determines if one of the attributes passed in is the inheritance column, and if the inheritance column is attr accessible, it initializes an instance of the given subclass instead of the base class.
# File lib/duck_record/inheritance.rb, line 42 def new(*args, &block) if abstract_class? || self == Base raise NotImplementedError, "#{self} is an abstract class and cannot be instantiated." end super end
Protected Instance Methods
Returns the class type of the record using the current module as a prefix. So descendants of MyApp::Business::Account would appear as MyApp::Business::AccountSubclass.
# File lib/duck_record/inheritance.rb, line 101 def compute_type(type_name) if type_name.start_with?("::".freeze) # If the type is prefixed with a scope operator then we assume that # the type_name is an absolute reference. ActiveSupport::Dependencies.constantize(type_name) else type_candidate = @_type_candidates_cache[type_name] if type_candidate && type_constant = ActiveSupport::Dependencies.safe_constantize(type_candidate) return type_constant end # Build a list of candidates to search for candidates = [] type_name.scan(/::|$/) { candidates.unshift "#{$`}::#{type_name}" } candidates << type_name candidates.each do |candidate| constant = ActiveSupport::Dependencies.safe_constantize(candidate) if candidate == constant.to_s @_type_candidates_cache[type_name] = candidate return constant end end raise NameError.new("uninitialized constant #{candidates.first}", candidates.first) end end