Module: ActiveRecord::AttributeMethods::Read
- Extended by:
- ActiveSupport::Concern
- Defined in:
- lib/active_record/attribute_methods/read.rb
Defined Under Namespace
Modules: ClassMethods
Constant Summary collapse
- ReaderMethodCache =
Class.new(AttributeMethodCache) { private # We want to generate the methods via module_eval rather than # define_method, because define_method is slower on dispatch. # Evaluating many similar methods may use more memory as the instruction # sequences are duplicated and cached (in MRI). define_method may # be slower on dispatch, but if you're careful about the closure # created, then define_method will consume much less memory. # # But sometimes the database might return columns with # characters that are not allowed in normal method names (like # 'my_column(omg)'. So to work around this we first define with # the __temp__ identifier, and then use alias method to rename # it to what we want. # # We are also defining a constant to hold the frozen string of # the attribute name. Using a constant means that we do not have # to allocate an object on each call to the attribute method. # Making it frozen means that it doesn't get duped when used to # key the @attributes in read_attribute. def method_body(method_name, const_name) "def \#{method_name}\nname = ::ActiveRecord::AttributeMethods::AttrNames::ATTR_\#{const_name}\n_read_attribute(name) { |n| missing_attribute(n, caller) }\nend\n" end }.new
- ID =
'id'.freeze
Instance Method Summary collapse
-
#_read_attribute(attr_name) ⇒ Object
This method exists to avoid the expensive primary_key check internally, without breaking compatibility with the read_attribute API.
-
#read_attribute(attr_name, &block) ⇒ Object
Returns the value of the attribute identified by
attr_name
after it has been typecast (for example, “2004-12-12” in a date column is cast to a date object, like Date.new(2004, 12, 12)).
Instance Method Details
#_read_attribute(attr_name) ⇒ Object
This method exists to avoid the expensive primary_key check internally, without breaking compatibility with the read_attribute API
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# File 'lib/active_record/attribute_methods/read.rb', line 92 def _read_attribute(attr_name) # :nodoc: @attributes.fetch_value(attr_name.to_s) { |n| yield n if block_given? } end |
#read_attribute(attr_name, &block) ⇒ Object
Returns the value of the attribute identified by attr_name
after it has been typecast (for example, “2004-12-12” in a date column is cast to a date object, like Date.new(2004, 12, 12)).
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# File 'lib/active_record/attribute_methods/read.rb', line 84 def read_attribute(attr_name, &block) name = attr_name.to_s name = self.class.primary_key if name == ID _read_attribute(name, &block) end |