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Diffstat (limited to 'activerecord/lib/active_record/model_schema.rb')
| -rw-r--r-- | activerecord/lib/active_record/model_schema.rb | 542 |
1 files changed, 542 insertions, 0 deletions
diff --git a/activerecord/lib/active_record/model_schema.rb b/activerecord/lib/active_record/model_schema.rb new file mode 100644 index 0000000000..55fc58e339 --- /dev/null +++ b/activerecord/lib/active_record/model_schema.rb @@ -0,0 +1,542 @@ +# frozen_string_literal: true + +require "monitor" + +module ActiveRecord + module ModelSchema + extend ActiveSupport::Concern + + ## + # :singleton-method: primary_key_prefix_type + # :call-seq: primary_key_prefix_type + # + # 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. + + ## + # :singleton-method: primary_key_prefix_type= + # :call-seq: primary_key_prefix_type=(prefix_type) + # + # Sets 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. + + ## + # :singleton-method: table_name_prefix + # :call-seq: table_name_prefix + # + # The prefix string to prepend to every table name. + + ## + # :singleton-method: table_name_prefix= + # :call-seq: table_name_prefix=(prefix) + # + # Sets 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. + + ## + # :singleton-method: table_name_suffix + # :call-seq: table_name_suffix + # + # The suffix string to append to every table name. + + ## + # :singleton-method: table_name_suffix= + # :call-seq: table_name_suffix=(suffix) + # + # 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. + + ## + # :singleton-method: schema_migrations_table_name + # :call-seq: schema_migrations_table_name + # + # The name of the schema migrations table. By default, the value is <tt>"schema_migrations"</tt>. + + ## + # :singleton-method: schema_migrations_table_name= + # :call-seq: schema_migrations_table_name=(table_name) + # + # Sets the name of the schema migrations table. + + ## + # :singleton-method: internal_metadata_table_name + # :call-seq: internal_metadata_table_name + # + # The name of the internal metadata table. By default, the value is <tt>"ar_internal_metadata"</tt>. + + ## + # :singleton-method: internal_metadata_table_name= + # :call-seq: internal_metadata_table_name=(table_name) + # + # Sets the name of the internal metadata table. + + ## + # :singleton-method: pluralize_table_names + # :call-seq: pluralize_table_names + # + # 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. + + ## + # :singleton-method: pluralize_table_names= + # :call-seq: pluralize_table_names=(value) + # + # Set 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. + + ## + # :singleton-method: implicit_order_column + # :call-seq: implicit_order_column + # + # The name of the column records are ordered by if no explicit order clause + # is used during an ordered finder call. If not set the primary key is used. + + ## + # :singleton-method: implicit_order_column= + # :call-seq: implicit_order_column=(column_name) + # + # Sets the column to sort records by when no explicit order clause is used + # during an ordered finder call. Useful when the primary key is not an + # auto-incrementing integer, for example when it's a UUID. Note that using + # a non-unique column can result in non-deterministic results. + included do + mattr_accessor :primary_key_prefix_type, instance_writer: false + + class_attribute :table_name_prefix, instance_writer: false, default: "" + class_attribute :table_name_suffix, instance_writer: false, default: "" + class_attribute :schema_migrations_table_name, instance_accessor: false, default: "schema_migrations" + class_attribute :internal_metadata_table_name, instance_accessor: false, default: "ar_internal_metadata" + class_attribute :pluralize_table_names, instance_writer: false, default: true + class_attribute :implicit_order_column, instance_accessor: false + + self.protected_environments = ["production"] + self.inheritance_column = "type" + self.ignored_columns = [].freeze + + delegate :type_for_attribute, to: :class + + initialize_load_schema_monitor + 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: + (module_parents.detect { |p| p.respond_to?(:table_name_prefix) } || self).table_name_prefix + end + + def full_table_name_suffix #:nodoc: + (module_parents.detect { |p| p.respond_to?(:table_name_suffix) } || self).table_name_suffix + end + + # The array of names of environments where destructive actions should be prohibited. By default, + # the value is <tt>["production"]</tt>. + def protected_environments + if defined?(@protected_environments) + @protected_environments + else + superclass.protected_environments + end + end + + # Sets an array of names of environments where destructive actions should be prohibited. + def protected_environments=(environments) + @protected_environments = environments.map(&:to_s) + 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 + + # The list of columns names the model should ignore. Ignored columns won't have attribute + # accessors defined, and won't be referenced in SQL queries. + def ignored_columns + if defined?(@ignored_columns) + @ignored_columns + else + superclass.ignored_columns + end + end + + # Sets the columns names the model should ignore. Ignored columns won't have attribute + # accessors defined, and won't be referenced in SQL queries. + def ignored_columns=(columns) + @ignored_columns = columns.map(&:to_s) + end + + def sequence_name + if base_class? + @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 + + # Determines if the primary key values should be selected from their + # corresponding sequence before the insert statement. + def prefetch_primary_key? + connection.prefetch_primary_key?(table_name) + end + + # Returns the next value that will be used as the primary key on + # an insert statement. + def next_sequence_value + connection.next_sequence_value(sequence_name) + end + + # Indicates whether the table associated with this class exists + def table_exists? + connection.schema_cache.data_source_exists?(table_name) + end + + def attributes_builder # :nodoc: + unless defined?(@attributes_builder) && @attributes_builder + defaults = _default_attributes.except(*(column_names - [primary_key])) + @attributes_builder = ActiveModel::AttributeSet::Builder.new(attribute_types, defaults) + end + @attributes_builder + 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.default_value) + end + + def yaml_encoder # :nodoc: + @yaml_encoder ||= ActiveModel::AttributeSet::YAMLEncoder.new(attribute_types) + end + + # Returns the type of the attribute with the given name, after applying + # all modifiers. This method is the only valid source of information for + # anything related to the types of a model's attributes. This method will + # access the database and load the model's schema if it is required. + # + # The return value of this method will implement the interface described + # by ActiveModel::Type::Value (though the object itself may not subclass + # it). + # + # +attr_name+ The name of the attribute to retrieve the type for. Must be + # a string or a symbol. + def type_for_attribute(attr_name, &block) + attr_name = attr_name.to_s + if block + attribute_types.fetch(attr_name, &block) + else + attribute_types[attr_name] + end + end + + # Returns a hash where the keys are column names and the values are + # default values when instantiating the Active Record object for this table. + def column_defaults + load_schema + @column_defaults ||= _default_attributes.deep_dup.to_hash + end + + def _default_attributes # :nodoc: + load_schema + @default_attributes ||= ActiveModel::AttributeSet.new({}) + end + + # Returns an array of column names as strings. + def column_names + @column_names ||= columns.map(&:name) + end + + def symbol_column_to_string(name_symbol) # :nodoc: + @symbol_column_to_string_name_hash ||= column_names.index_by(&:to_sym) + @symbol_column_to_string_name_hash[name_symbol] + 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 do |c| + c.name == primary_key || + c.name == inheritance_column || + c.name.end_with?("_id") || + c.name.end_with?("_count") + end + 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[5.0] + # 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! + ([self] + descendants).each(&:undefine_attribute_methods) + connection.schema_cache.clear_data_source_cache!(table_name) + + reload_schema_from_cache + initialize_find_by_cache + end + + protected + + def initialize_load_schema_monitor + @load_schema_monitor = Monitor.new + end + + private + + def inherited(child_class) + super + child_class.initialize_load_schema_monitor + end + + def schema_loaded? + defined?(@schema_loaded) && @schema_loaded + end + + def load_schema + return if schema_loaded? + @load_schema_monitor.synchronize do + return if defined?(@columns_hash) && @columns_hash + + load_schema! + + @schema_loaded = true + end + end + + def load_schema! + @columns_hash = connection.schema_cache.columns_hash(table_name).except(*ignored_columns) + @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_table = nil + @column_names = nil + @symbol_column_to_string_name_hash = nil + @attribute_types = nil + @content_columns = nil + @default_attributes = nil + @column_defaults = nil + @inheritance_column = nil unless defined?(@explicit_inheritance_column) && @explicit_inheritance_column + @attributes_builder = nil + @columns = nil + @columns_hash = nil + @schema_loaded = false + @attribute_names = nil + @yaml_encoder = nil + direct_descendants.each do |descendant| + descendant.send(:reload_schema_from_cache) + end + 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 + if base_class? + # Nested classes are prefixed with singular parent table name. + if module_parent < Base && !module_parent.abstract_class? + contained = module_parent.table_name + contained = contained.singularize if module_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_class.table_name + end + end + end + end +end |