Module: ActiveRecord::AttributeMethods
- Extended by:
- ActiveSupport::Autoload, ActiveSupport::Concern
- Includes:
- ActiveModel::AttributeMethods
- Included in:
- Base
- Defined in:
- lib/active_record/attribute_methods.rb,
lib/active_record.rb,
lib/active_record/attribute_methods/read.rb,
lib/active_record/attribute_methods/dirty.rb,
lib/active_record/attribute_methods/query.rb,
lib/active_record/attribute_methods/write.rb,
lib/active_record/attribute_methods/primary_key.rb,
lib/active_record/attribute_methods/serialization.rb,
lib/active_record/attribute_methods/before_type_cast.rb,
lib/active_record/attribute_methods/time_zone_conversion.rb
Overview
Active Record Attribute Methods
Defined Under Namespace
Modules: BeforeTypeCast, ClassMethods, Dirty, PrimaryKey, Query, Read, Serialization, TimeZoneConversion, Write Classes: AttributeMethodCache, GeneratedAttributeMethods
Constant Summary collapse
- AttrNames =
Module.new { def self.set_name_cache(name, value) const_name = "ATTR_#{name}" unless const_defined? const_name const_set const_name, value.dup.freeze end end }
- BLACKLISTED_CLASS_METHODS =
%w(private public protected allocate new name parent superclass)
Instance Method Summary collapse
-
#[](attr_name) ⇒ 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)). -
#[]=(attr_name, value) ⇒ Object
Updates the attribute identified by
attr_name
with the specifiedvalue
. -
#attribute_for_inspect(attr_name) ⇒ Object
Returns an
#inspect
-like string for the value of the attributeattr_name
. -
#attribute_names ⇒ Object
Returns an array of names for the attributes available on this object.
-
#attribute_present?(attribute) ⇒ Boolean
Returns
true
if the specifiedattribute
has been set by the user or by a database load and is neithernil
norempty?
(the latter only applies to objects that respond toempty?
, most notably Strings). -
#attributes ⇒ Object
Returns a hash of all the attributes with their names as keys and the values of the attributes as values.
-
#attributes_for_coder ⇒ Object
Placeholder so it can be overriden when needed by serialization.
-
#column_for_attribute(name) ⇒ Object
Returns the column object for the named attribute.
-
#has_attribute?(attr_name) ⇒ Boolean
Returns
true
if the given attribute is in the attributes hash, otherwisefalse
. -
#method_missing(method, *args, &block) ⇒ Object
If we haven’t generated any methods yet, generate them, then see if we’ve created the method we’re looking for.
-
#respond_to?(name, include_private = false) ⇒ Boolean
A Person object with a name attribute can ask
person.respond_to?(:name)
,person.respond_to?(:name=)
, andperson.respond_to?(:name?)
which will all returntrue
.
Dynamic Method Handling
This class handles dynamic methods through the method_missing method
#method_missing(method, *args, &block) ⇒ Object
If we haven’t generated any methods yet, generate them, then see if we’ve created the method we’re looking for.
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# File 'lib/active_record/attribute_methods.rb', line 200 def method_missing(method, *args, &block) # :nodoc: self.class.define_attribute_methods if respond_to_without_attributes?(method) # make sure to invoke the correct attribute method, as we might have gotten here via a `super` # call in a overwritten attribute method if attribute_method = self.class.find_generated_attribute_method(method) # this is probably horribly slow, but should only happen at most once for a given AR class attribute_method.bind(self).call(*args, &block) else return super unless respond_to_missing?(method, true) send(method, *args, &block) end else super end end |
Instance Method Details
#[](attr_name) ⇒ 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)). It raises ActiveModel::MissingAttributeError
if the identified attribute is missing.
Alias for the read_attribute
method.
class Person < ActiveRecord::Base
belongs_to :organization
end
person = Person.new(name: 'Francesco', age: '22')
person[:name] # => "Francesco"
person[:age] # => 22
person = Person.select('id').first
person[:name] # => ActiveModel::MissingAttributeError: missing attribute: name
person[:organization_id] # => ActiveModel::MissingAttributeError: missing attribute: organization_id
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# File 'lib/active_record/attribute_methods.rb', line 382 def [](attr_name) read_attribute(attr_name) { |n| missing_attribute(n, caller) } end |
#[]=(attr_name, value) ⇒ Object
Updates the attribute identified by attr_name
with the specified value
. (Alias for the protected write_attribute
method).
class Person < ActiveRecord::Base
end
person = Person.new
person[:age] = '22'
person[:age] # => 22
person[:age] # => Fixnum
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# File 'lib/active_record/attribute_methods.rb', line 396 def []=(attr_name, value) write_attribute(attr_name, value) end |
#attribute_for_inspect(attr_name) ⇒ Object
Returns an #inspect
-like string for the value of the attribute attr_name
. String attributes are truncated upto 50 characters, Date and Time attributes are returned in the :db
format, Array attributes are truncated upto 10 values. Other attributes return the value of #inspect
without modification.
person = Person.create!(name: 'David Heinemeier Hansson ' * 3)
person.attribute_for_inspect(:name)
# => "\"David Heinemeier Hansson David Heinemeier Hansson ...\""
person.attribute_for_inspect(:created_at)
# => "\"2012-10-22 00:15:07\""
person.attribute_for_inspect(:tag_ids)
# => "[1, 2, 3, 4, 5, 6, 7, 8, 9, 10, ...]"
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# File 'lib/active_record/attribute_methods.rb', line 313 def attribute_for_inspect(attr_name) value = read_attribute(attr_name) if value.is_a?(String) && value.length > 50 "#{value[0, 50]}...".inspect elsif value.is_a?(Date) || value.is_a?(Time) %("#{value.to_s(:db)}") elsif value.is_a?(Array) && value.size > 10 inspected = value.first(10).inspect %(#{inspected[0...-1]}, ...]) else value.inspect end end |
#attribute_names ⇒ Object
Returns an array of names for the attributes available on this object.
class Person < ActiveRecord::Base
end
person = Person.new
person.attribute_names
# => ["id", "created_at", "updated_at", "name", "age"]
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# File 'lib/active_record/attribute_methods.rb', line 273 def attribute_names @attributes.keys end |
#attribute_present?(attribute) ⇒ Boolean
Returns true
if the specified attribute
has been set by the user or by a database load and is neither nil
nor empty?
(the latter only applies to objects that respond to empty?
, most notably Strings). Otherwise, false
. Note that it always returns true
with boolean attributes.
class Task < ActiveRecord::Base
end
person = Task.new(title: '', is_done: false)
person.attribute_present?(:title) # => false
person.attribute_present?(:is_done) # => true
person.name = 'Francesco'
person.is_done = true
person.attribute_present?(:title) # => true
person.attribute_present?(:is_done) # => true
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# File 'lib/active_record/attribute_methods.rb', line 343 def attribute_present?(attribute) value = read_attribute(attribute) !value.nil? && !(value.respond_to?(:empty?) && value.empty?) end |
#attributes ⇒ Object
Returns a hash of all the attributes with their names as keys and the values of the attributes as values.
class Person < ActiveRecord::Base
end
person = Person.create(name: 'Francesco', age: 22)
person.attributes
# => {"id"=>3, "created_at"=>Sun, 21 Oct 2012 04:53:04, "updated_at"=>Sun, 21 Oct 2012 04:53:04, "name"=>"Francesco", "age"=>22}
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# File 'lib/active_record/attribute_methods.rb', line 285 def attributes attribute_names.each_with_object({}) { |name, attrs| attrs[name] = read_attribute(name) } end |
#attributes_for_coder ⇒ Object
Placeholder so it can be overriden when needed by serialization
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# File 'lib/active_record/attribute_methods.rb', line 292 def attributes_for_coder # :nodoc: attributes end |
#column_for_attribute(name) ⇒ Object
Returns the column object for the named attribute. Returns nil
if the named attribute not exists.
class Person < ActiveRecord::Base
end
person = Person.new
person.column_for_attribute(:name) # the result depends on the ConnectionAdapter
# => #<ActiveRecord::ConnectionAdapters::SQLite3Column:0x007ff4ab083980 @name="name", @sql_type="varchar(255)", @null=true, ...>
person.column_for_attribute(:nothing)
# => nil
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# File 'lib/active_record/attribute_methods.rb', line 360 def column_for_attribute(name) # FIXME: should this return a null object for columns that don't exist? self.class.columns_hash[name.to_s] end |
#has_attribute?(attr_name) ⇒ Boolean
Returns true
if the given attribute is in the attributes hash, otherwise false
.
class Person < ActiveRecord::Base
end
person = Person.new
person.has_attribute?(:name) # => true
person.has_attribute?('age') # => true
person.has_attribute?(:nothing) # => false
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# File 'lib/active_record/attribute_methods.rb', line 261 def has_attribute?(attr_name) @attributes.has_key?(attr_name.to_s) end |
#respond_to?(name, include_private = false) ⇒ Boolean
A Person object with a name attribute can ask person.respond_to?(:name)
, person.respond_to?(:name=)
, and person.respond_to?(:name?)
which will all return true
. It also define the attribute methods if they have not been generated.
class Person < ActiveRecord::Base
end
person = Person.new
person.respond_to(:name) # => true
person.respond_to(:name=) # => true
person.respond_to(:name?) # => true
person.respond_to('age') # => true
person.respond_to('age=') # => true
person.respond_to('age?') # => true
person.respond_to(:nothing) # => false
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# File 'lib/active_record/attribute_methods.rb', line 233 def respond_to?(name, include_private = false) name = name.to_s self.class.define_attribute_methods result = super # If the result is false the answer is false. return false unless result # If the result is true then check for the select case. # For queries selecting a subset of columns, return false for unselected columns. # We check defined?(@attributes) not to issue warnings if called on objects that # have been allocated but not yet initialized. if defined?(@attributes) && @attributes.any? && self.class.column_names.include?(name) return has_attribute?(name) end return true end |