module ActiveRecord::Enum
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)
Constants
- ENUM_CONFLICT_MESSAGE
Public Instance Methods
Source
# File lib/active_record/enum.rb, line 216 def enum(name, values = nil, **options) values, options = options, {} unless values _enum(name, values, **options) end
Private Instance Methods
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# File lib/active_record/enum.rb, line 222 def _enum(name, values, prefix: nil, suffix: nil, scopes: true, instance_methods: true, validate: false, **options) assert_valid_enum_definition_values(values) assert_valid_enum_options(options) # statuses = { } enum_values = ActiveSupport::HashWithIndifferentAccess.new name = name.to_s # def self.statuses() statuses end detect_enum_conflict!(name, name.pluralize, true) singleton_class.define_method(name.pluralize) { enum_values } defined_enums[name] = enum_values detect_enum_conflict!(name, name) detect_enum_conflict!(name, "#{name}=") attribute(name, **options) decorate_attributes([name]) do |_name, subtype| if subtype == ActiveModel::Type.default_value raise "Undeclared attribute type for enum '#{name}' in #{self.name}. Enums must be" \ " backed by a database column or declared with an explicit type" \ " via `attribute`." end subtype = subtype.subtype if EnumType === subtype EnumType.new(name, enum_values, subtype, raise_on_invalid_values: !validate) end value_method_names = [] _enum_methods_module.module_eval do prefix = if prefix prefix == true ? "#{name}_" : "#{prefix}_" end suffix = if suffix suffix == true ? "_#{name}" : "_#{suffix}" end pairs = values.respond_to?(:each_pair) ? values.each_pair : values.each_with_index pairs.each do |label, value| enum_values[label] = value label = label.to_s value_method_name = "#{prefix}#{label}#{suffix}" value_method_names << value_method_name define_enum_methods(name, value_method_name, value, scopes, instance_methods) method_friendly_label = label.gsub(/[\W&&[:ascii:]]+/, "_") value_method_alias = "#{prefix}#{method_friendly_label}#{suffix}" if value_method_alias != value_method_name && !value_method_names.include?(value_method_alias) value_method_names << value_method_alias define_enum_methods(name, value_method_alias, value, scopes, instance_methods) end end end detect_negative_enum_conditions!(value_method_names) if scopes if validate validate = {} unless Hash === validate validates_inclusion_of name, in: enum_values.keys, **validate end enum_values.freeze end
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# File lib/active_record/enum.rb, line 326 def _enum_methods_module @_enum_methods_module ||= begin mod = EnumMethods.new(self) include mod mod end end
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# File lib/active_record/enum.rb, line 334 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
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# File lib/active_record/enum.rb, line 361 def assert_valid_enum_options(options) invalid_keys = options.keys & %i[_prefix _suffix _scopes _default _instance_methods] unless invalid_keys.empty? raise ArgumentError, "invalid option(s): #{invalid_keys.map(&:inspect).join(", ")}. Valid options are: :prefix, :suffix, :scopes, :default, :instance_methods, and :validate." end end
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# File lib/active_record/enum.rb, line 374 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
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# File lib/active_record/enum.rb, line 398 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
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# File lib/active_record/enum.rb, line 289 def inherited(base) base.defined_enums = defined_enums.deep_dup super end
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# File lib/active_record/enum.rb, line 388 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