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# frozen_string_literal: true
require "active_support/core_ext/object/deep_dup"
module ActiveRecord
# 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.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)
#
# You can set the default value from the database declaration, like:
#
# create_table :conversations do |t|
# t.column :status, :integer, default: 0
# end
#
# Good practice is to let the first declared status be the default.
#
# Finally, it's also 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
#
# 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,
# <tt>:active</tt> is mapped to +0+ as it's the first element, and <tt>:archived</tt>
# is mapped to +1+. In general, the +i+-th element is mapped to <tt>i-1</tt> 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 +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
module Enum
def self.extended(base) # :nodoc:
base.class_attribute(:defined_enums, instance_writer: false, default: {})
end
def inherited(base) # :nodoc:
base.defined_enums = defined_enums.deep_dup
super
end
class EnumType < Type::Value # :nodoc:
delegate :type, to: :subtype
def initialize(name, mapping, subtype)
@name = name
@mapping = mapping
@subtype = subtype
end
def cast(value)
return if value.blank?
if mapping.has_key?(value)
value.to_s
elsif mapping.has_value?(value)
mapping.key(value)
else
assert_valid_value(value)
end
end
def deserialize(value)
return if value.nil?
mapping.key(subtype.deserialize(value))
end
def serialize(value)
mapping.fetch(value, value)
end
def assert_valid_value(value)
unless value.blank? || mapping.has_key?(value) || mapping.has_value?(value)
raise ArgumentError, "'#{value}' is not a valid #{name}"
end
end
private
attr_reader :name, :mapping, :subtype
end
def enum(definitions)
klass = self
enum_prefix = definitions.delete(:_prefix)
enum_suffix = definitions.delete(:_suffix)
definitions.each do |name, values|
# statuses = { }
enum_values = ActiveSupport::HashWithIndifferentAccess.new
name = name.to_s
# def self.statuses() statuses end
detect_enum_conflict!(name, name.pluralize, true)
singleton_class.send(:define_method, name.pluralize) { enum_values }
defined_enums[name] = enum_values
detect_enum_conflict!(name, name)
detect_enum_conflict!(name, "#{name}=")
attr = attribute_alias?(name) ? attribute_alias(name) : name
decorate_attribute_type(attr, :enum) do |subtype|
EnumType.new(attr, enum_values, subtype)
end
_enum_methods_module.module_eval do
pairs = values.respond_to?(:each_pair) ? values.each_pair : values.each_with_index
pairs.each do |label, value|
if enum_prefix == true
prefix = "#{name}_"
elsif enum_prefix
prefix = "#{enum_prefix}_"
end
if enum_suffix == true
suffix = "_#{name}"
elsif enum_suffix
suffix = "_#{enum_suffix}"
end
value_method_name = "#{prefix}#{label}#{suffix}"
enum_values[label] = value
label = label.to_s
# def active?() status == "active" end
klass.send(:detect_enum_conflict!, name, "#{value_method_name}?")
define_method("#{value_method_name}?") { self[attr] == label }
# def active!() update!(status: 0) end
klass.send(:detect_enum_conflict!, name, "#{value_method_name}!")
define_method("#{value_method_name}!") { update!(attr => value) }
# scope :active, -> { where(status: 0) }
klass.send(:detect_enum_conflict!, name, value_method_name, true)
klass.scope value_method_name, -> { where(attr => value) }
end
end
end
end
private
def _enum_methods_module
@_enum_methods_module ||= begin
mod = Module.new
include mod
mod
end
end
ENUM_CONFLICT_MESSAGE = \
"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}."
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 && 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
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
end
end
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