module ActiveRecord module ModelSchema extend ActiveSupport::Concern included do ## # :singleton-method: # Accessor for the prefix type that will be prepended to every primary key column name. # The options are :table_name and :table_name_with_underscore. If the first is specified, # the Product class will look for "productid" instead of "id" as the primary column. If the # latter is specified, the Product class will look for "product_id" instead of "id". Remember # that this is a global setting for all Active Records. mattr_accessor :primary_key_prefix_type, instance_writer: false ## # :singleton-method: # Accessor for the name of the prefix string to prepend to every table name. So if set # to "basecamp_", all table names will be named like "basecamp_projects", "basecamp_people", # etc. This is a convenient way of creating a namespace for tables in a shared database. # By default, the prefix is the empty string. # # If you are organising your models within modules you can add a prefix to the models within # a namespace by defining a singleton method in the parent module called table_name_prefix which # returns your chosen prefix. class_attribute :table_name_prefix, instance_writer: false self.table_name_prefix = "" ## # :singleton-method: # Works like +table_name_prefix+, but appends instead of prepends (set to "_basecamp" gives "projects_basecamp", # "people_basecamp"). By default, the suffix is the empty string. # # If you are organising your models within modules, you can add a suffix to the models within # a namespace by defining a singleton method in the parent module called table_name_suffix which # returns your chosen suffix. class_attribute :table_name_suffix, instance_writer: false self.table_name_suffix = "" ## # :singleton-method: # Accessor for the name of the schema migrations table. By default, the value is "schema_migrations" class_attribute :schema_migrations_table_name, instance_accessor: false self.schema_migrations_table_name = "schema_migrations" ## # :singleton-method: # Indicates whether table names should be the pluralized versions of the corresponding class names. # If true, the default table name for a Product class will be +products+. If false, it would just be +product+. # See table_name for the full rules on table/class naming. This is true, by default. class_attribute :pluralize_table_names, instance_writer: false self.pluralize_table_names = true self.inheritance_column = 'type' delegate :type_for_attribute, to: :class end # Derives the join table name for +first_table+ and +second_table+. The # table names appear in alphabetical order. A common prefix is removed # (useful for namespaced models like Music::Artist and Music::Record): # # artists, records => artists_records # records, artists => artists_records # music_artists, music_records => music_artists_records def self.derive_join_table_name(first_table, second_table) # :nodoc: [first_table.to_s, second_table.to_s].sort.join("\0").gsub(/^(.*_)(.+)\0\1(.+)/, '\1\2_\3').tr("\0", "_") end module ClassMethods # Guesses the table name (in forced lower-case) based on the name of the class in the # inheritance hierarchy descending directly from ActiveRecord::Base. So if the hierarchy # looks like: Reply < Message < ActiveRecord::Base, then Message is used # to guess the table name even when called on Reply. The rules used to do the guess # are handled by the Inflector class in Active Support, which knows almost all common # English inflections. You can add new inflections in config/initializers/inflections.rb. # # Nested classes are given table names prefixed by the singular form of # the parent's table name. Enclosing modules are not considered. # # ==== Examples # # class Invoice < ActiveRecord::Base # end # # file class table_name # invoice.rb Invoice invoices # # class Invoice < ActiveRecord::Base # class Lineitem < ActiveRecord::Base # end # end # # file class table_name # invoice.rb Invoice::Lineitem invoice_lineitems # # module Invoice # class Lineitem < ActiveRecord::Base # end # end # # file class table_name # invoice/lineitem.rb Invoice::Lineitem lineitems # # Additionally, the class-level +table_name_prefix+ is prepended and the # +table_name_suffix+ is appended. So if you have "myapp_" as a prefix, # the table name guess for an Invoice class becomes "myapp_invoices". # Invoice::Lineitem becomes "myapp_invoice_lineitems". # # You can also set your own table name explicitly: # # class Mouse < ActiveRecord::Base # self.table_name = "mice" # end def table_name reset_table_name unless defined?(@table_name) @table_name end # Sets the table name explicitly. Example: # # class Project < ActiveRecord::Base # self.table_name = "project" # end def table_name=(value) value = value && value.to_s if defined?(@table_name) return if value == @table_name reset_column_information if connected? end @table_name = value @quoted_table_name = nil @arel_table = nil @sequence_name = nil unless defined?(@explicit_sequence_name) && @explicit_sequence_name @predicate_builder = nil end # Returns a quoted version of the table name, used to construct SQL statements. def quoted_table_name @quoted_table_name ||= connection.quote_table_name(table_name) end # Computes the table name, (re)sets it internally, and returns it. def reset_table_name #:nodoc: self.table_name = if abstract_class? superclass == Base ? nil : superclass.table_name elsif superclass.abstract_class? superclass.table_name || compute_table_name else compute_table_name end end def full_table_name_prefix #:nodoc: (parents.detect{ |p| p.respond_to?(:table_name_prefix) } || self).table_name_prefix end def full_table_name_suffix #:nodoc: (parents.detect {|p| p.respond_to?(:table_name_suffix) } || self).table_name_suffix end # Defines the name of the table column which will store the class name on single-table # inheritance situations. # # The default inheritance column name is +type+, which means it's a # reserved word inside Active Record. To be able to use single-table # inheritance with another column name, or to use the column +type+ in # your own model for something else, you can set +inheritance_column+: # # self.inheritance_column = 'zoink' def inheritance_column (@inheritance_column ||= nil) || superclass.inheritance_column end # Sets the value of inheritance_column def inheritance_column=(value) @inheritance_column = value.to_s @explicit_inheritance_column = true end def sequence_name if base_class == self @sequence_name ||= reset_sequence_name else (@sequence_name ||= nil) || base_class.sequence_name end end def reset_sequence_name #:nodoc: @explicit_sequence_name = false @sequence_name = connection.default_sequence_name(table_name, primary_key) end # Sets the name of the sequence to use when generating ids to the given # value, or (if the value is nil or false) to the value returned by the # given block. This is required for Oracle and is useful for any # database which relies on sequences for primary key generation. # # If a sequence name is not explicitly set when using Oracle, # it will default to the commonly used pattern of: #{table_name}_seq # # If a sequence name is not explicitly set when using PostgreSQL, it # will discover the sequence corresponding to your primary key for you. # # class Project < ActiveRecord::Base # self.sequence_name = "projectseq" # default would have been "project_seq" # end def sequence_name=(value) @sequence_name = value.to_s @explicit_sequence_name = true end # Indicates whether the table associated with this class exists def table_exists? connection.schema_cache.table_exists?(table_name) end def attributes_builder # :nodoc: @attributes_builder ||= AttributeSet::Builder.new(attribute_types, primary_key) end def columns_hash # :nodoc: load_schema @columns_hash end def columns load_schema @columns ||= columns_hash.values end def attribute_types # :nodoc: load_schema @attribute_types ||= Hash.new(Type::Value.new) end def type_for_attribute(attr_name) # :nodoc: attribute_types[attr_name] end # Returns a hash where the keys are column names and the values are # default values when instantiating the AR object for this table. def column_defaults load_schema _default_attributes.to_hash end def _default_attributes # :nodoc: @default_attributes ||= AttributeSet.new({}) end # Returns an array of column names as strings. def column_names @column_names ||= columns.map(&:name) end # Returns an array of column objects where the primary id, all columns ending in "_id" or "_count", # and columns used for single table inheritance have been removed. def content_columns @content_columns ||= columns.reject { |c| c.name == primary_key || c.name =~ /(_id|_count)$/ || c.name == inheritance_column } end # Resets all the cached information about columns, which will cause them # to be reloaded on the next request. # # The most common usage pattern for this method is probably in a migration, # when just after creating a table you want to populate it with some default # values, eg: # # class CreateJobLevels < ActiveRecord::Migration # def up # create_table :job_levels do |t| # t.integer :id # t.string :name # # t.timestamps # end # # JobLevel.reset_column_information # %w{assistant executive manager director}.each do |type| # JobLevel.create(name: type) # end # end # # def down # drop_table :job_levels # end # end def reset_column_information connection.clear_cache! undefine_attribute_methods connection.schema_cache.clear_table_cache!(table_name) reload_schema_from_cache end private def schema_loaded? defined?(@columns_hash) && @columns_hash end def load_schema unless schema_loaded? load_schema! end end def load_schema! @columns_hash = connection.schema_cache.columns_hash(table_name) @columns_hash.each do |name, column| define_attribute( name, connection.lookup_cast_type_from_column(column), default: column.default, user_provided_default: false ) end end def reload_schema_from_cache @arel_engine = nil @arel_table = nil @column_names = nil @attribute_types = nil @content_columns = nil @default_attributes = nil @inheritance_column = nil unless defined?(@explicit_inheritance_column) && @explicit_inheritance_column @attributes_builder = nil @columns = nil @columns_hash = nil @attribute_names = nil end # Guesses the table name, but does not decorate it with prefix and suffix information. def undecorated_table_name(class_name = base_class.name) table_name = class_name.to_s.demodulize.underscore pluralize_table_names ? table_name.pluralize : table_name end # Computes and returns a table name according to default conventions. def compute_table_name base = base_class if self == base # Nested classes are prefixed with singular parent table name. if parent < Base && !parent.abstract_class? contained = parent.table_name contained = contained.singularize if parent.pluralize_table_names contained += '_' end "#{full_table_name_prefix}#{contained}#{undecorated_table_name(name)}#{full_table_name_suffix}" else # STI subclasses always use their superclass' table. base.table_name end end end end end