Module: ActiveRecord::Enum
Relationships & Source Files | |
Extension / Inclusion / Inheritance Descendants | |
Extended In:
| |
Defined in: | activerecord/lib/active_record/enum.rb |
Overview
Declare an enum attribute where the values map to integers in the database, but can be queried by name. Example:
class Conversation < ActiveRecord::Base
enum :status, [ :active, :archived ]
end
# conversation.update! status: 0
conversation.active!
conversation.active? # => true
conversation.status # => "active"
# conversation.update! status: 1
conversation.archived!
conversation.archived? # => true
conversation.status # => "archived"
# conversation.status = 1
conversation.status = "archived"
conversation.status = nil
conversation.status.nil? # => true
conversation.status # => nil
Scopes based on the allowed values of the enum field will be provided as well. With the above example:
Conversation.active
Conversation.not_active
Conversation.archived
Conversation.not_archived
Of course, you can also query them directly if the scopes don’t fit your needs:
Conversation.where(status: [:active, :archived])
Conversation.where.not(status: :active)
Defining scopes can be disabled by setting :scopes
to false
.
class Conversation < ActiveRecord::Base
enum :status, [ :active, :archived ], scopes: false
end
You can set the default enum value by setting :default
, like:
class Conversation < ActiveRecord::Base
enum :status, [ :active, :archived ], default: :active
end
conversation = Conversation.new
conversation.status # => "active"
It’s possible to explicitly map the relation between attribute and database integer with a hash:
class Conversation < ActiveRecord::Base
enum :status, active: 0, archived: 1
end
Finally it’s also possible to use a string column to persist the enumerated value. Note that this will likely lead to slower database queries:
class Conversation < ActiveRecord::Base
enum :status, active: "active", archived: "archived"
end
Note that when an array is used, the implicit mapping from the values to database integers is derived from the order the values appear in the array. In the example, :active
is mapped to 0
as it’s the first element, and :archived
is mapped to 1
. In general, the i
-th element is mapped to i-1
in the database.
Therefore, once a value is added to the enum array, its position in the array must be maintained, and new values should only be added to the end of the array. To remove unused values, the explicit hash syntax should be used.
In rare circumstances you might need to access the mapping directly. The mappings are exposed through a class method with the pluralized attribute name, which return the mapping in a ::ActiveSupport::HashWithIndifferentAccess
:
Conversation.statuses[:active] # => 0
Conversation.statuses["archived"] # => 1
Use that class method when you need to know the ordinal value of an enum. For example, you can use that when manually building SQL strings:
Conversation.where("status <> ?", Conversation.statuses[:archived])
You can use the :prefix
or :suffix
options when you need to define multiple enums with same values. If the passed value is true
, the methods are prefixed/suffixed with the name of the enum. It is also possible to supply a custom value:
class Conversation < ActiveRecord::Base
enum :status, [ :active, :archived ], suffix: true
enum :comments_status, [ :active, :inactive ], prefix: :comments
end
With the above example, the bang and predicate methods along with the associated scopes are now prefixed and/or suffixed accordingly:
conversation.active_status!
conversation.archived_status? # => false
conversation.comments_inactive!
conversation.comments_active? # => false
If you want to disable the auto-generated methods on the model, you can do so by setting the :instance_methods
option to false:
class Conversation < ActiveRecord::Base
enum :status, [ :active, :archived ], instance_methods: false
end
If you want the enum value to be validated before saving, use the option :validate
:
class Conversation < ActiveRecord::Base
enum :status, [ :active, :archived ], validate: true
end
conversation = Conversation.new
conversation.status = :unknown
conversation.valid? # => false
conversation.status = nil
conversation.valid? # => false
conversation.status = :active
conversation.valid? # => true
It is also possible to pass additional validation options:
class Conversation < ActiveRecord::Base
enum :status, [ :active, :archived ], validate: { allow_nil: true }
end
conversation = Conversation.new
conversation.status = :unknown
conversation.valid? # => false
conversation.status = nil
conversation.valid? # => true
conversation.status = :active
conversation.valid? # => true
Otherwise ArgumentError
will raise:
class Conversation < ActiveRecord::Base
enum :status, [ :active, :archived ]
end
conversation = Conversation.new
conversation.status = :unknown # 'unknown' is not a valid status (ArgumentError)
Constant Summary
-
ENUM_CONFLICT_MESSAGE =
private
# File 'activerecord/lib/active_record/enum.rb', line 364"You tried to define an enum named \"%{enum}\" on the model \"%{klass}\", but " \ "this will generate a %{type} method \"%{method}\", which is already defined " \ "by %{source}."
Instance Method Summary
- #_enum_methods_module
- #assert_valid_enum_definition_values(values)
- #detect_enum_conflict!(enum_name, method_name, klass_method = false)
- #detect_negative_enum_conditions!(method_names)
- #enum(name = nil, values = nil, **options)
- #raise_conflict_error(enum_name, method_name, type: "instance", source: "Active Record")
Instance Method Details
#_enum_methods_module
[ GitHub ]# File 'activerecord/lib/active_record/enum.rb', line 329
def _enum_methods_module @_enum_methods_module ||= begin mod = EnumMethods.new(self) include mod mod end end
#assert_valid_enum_definition_values(values)
[ GitHub ]# File 'activerecord/lib/active_record/enum.rb', line 337
def assert_valid_enum_definition_values(values) case values when Hash if values.empty? raise ArgumentError, "Enum values #{values} must not be empty." end if values.keys.any?(&:blank?) raise ArgumentError, "Enum values #{values} must not contain a blank name." end when Array if values.empty? raise ArgumentError, "Enum values #{values} must not be empty." end unless values.all?(Symbol) || values.all?(String) raise ArgumentError, "Enum values #{values} must only contain symbols or strings." end if values.any?(&:blank?) raise ArgumentError, "Enum values #{values} must not contain a blank name." end else raise ArgumentError, "Enum values #{values} must be either a non-empty hash or an array." end end
#detect_enum_conflict!(enum_name, method_name, klass_method = false)
[ GitHub ]# File 'activerecord/lib/active_record/enum.rb', line 370
def detect_enum_conflict!(enum_name, method_name, klass_method = false) if klass_method && dangerous_class_method?(method_name) raise_conflict_error(enum_name, method_name, type: "class") elsif klass_method && method_defined_within?(method_name, Relation) raise_conflict_error(enum_name, method_name, type: "class", source: Relation.name) elsif klass_method && method_name.to_sym == :id raise_conflict_error(enum_name, method_name) elsif !klass_method && dangerous_attribute_method?(method_name) raise_conflict_error(enum_name, method_name) elsif !klass_method && method_defined_within?(method_name, _enum_methods_module, Module) raise_conflict_error(enum_name, method_name, source: "another enum") end end
#detect_negative_enum_conditions!(method_names)
[ GitHub ]# File 'activerecord/lib/active_record/enum.rb', line 394
def detect_negative_enum_conditions!(method_names) return unless logger method_names.select { |m| m.start_with?("not_") }.each do |potential_not| inverted_form = potential_not.sub("not_", "") if method_names.include?(inverted_form) logger.warn "Enum element '#{potential_not}' in #{self.name} uses the prefix 'not_'." \ " This has caused a conflict with auto generated negative scopes." \ " Avoid using enum elements starting with 'not' where the positive form is also an element." end end end
#enum(name = nil, values = nil, **options)
[ GitHub ]# File 'activerecord/lib/active_record/enum.rb', line 216
def enum(name = nil, values = nil, ** ) if name values, = , {} unless values return _enum(name, values, ** ) end definitions = .slice!(:_prefix, :_suffix, :_scopes, :_default, :_instance_methods) .transform_keys! { |key| :"#{key[1..-1]}" } definitions.each { |name, values| _enum(name, values, ** ) } end
#raise_conflict_error(enum_name, method_name, type: "instance", source: "Active Record")
# File 'activerecord/lib/active_record/enum.rb', line 384
def raise_conflict_error(enum_name, method_name, type: "instance", source: "Active Record") raise ArgumentError, ENUM_CONFLICT_MESSAGE % { enum: enum_name, klass: name, type: type, method: method_name, source: source } end