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.
class_attribute :table_name_suffix, instance_writer: false
self.table_name_suffix = ""
##
# :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'
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
#
# Alternatively, you can override the table_name method to define your
# own computation. (Possibly using <tt>super</tt> to manipulate the default
# table name.) Example:
#
# class Post < ActiveRecord::Base
# def self.table_name
# "special_" + super
# end
# end
# Post.table_name # => "special_posts"
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
#
# You can also just define your own <tt>self.table_name</tt> method; see
# the documentation for ActiveRecord::Base#table_name.
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
@relation = Relation.new(self, arel_table)
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
# 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 or Firebird,
# 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
# Returns an array of column objects for the table associated with this class.
def columns
@columns ||= connection.schema_cache.columns(table_name).map do |col|
col = col.dup
col.primary = (col.name == primary_key)
col
end
end
# Returns a hash of column objects for the table associated with this class.
def columns_hash
@columns_hash ||= Hash[columns.map { |c| [c.name, c] }]
end
def column_types # :nodoc:
@column_types ||= decorate_columns(columns_hash.dup)
end
def decorate_columns(columns_hash) # :nodoc:
return if columns_hash.empty?
columns_hash.each do |name, col|
if serialized_attributes.key?(name)
columns_hash[name] = AttributeMethods::Serialization::Type.new(col)
end
if create_time_zone_conversion_attribute?(name, col)
columns_hash[name] = AttributeMethods::TimeZoneConversion::Type.new(col)
end
end
columns_hash
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
@column_defaults ||= Hash[columns.map { |c| [c.name, c.default] }]
end
# Returns an array of column names as strings.
def column_names
@column_names ||= columns.map { |column| column.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.primary || c.name =~ /(_id|_count)$/ || c.name == inheritance_column }
end
# Returns a hash of all the methods added to query each of the columns in the table with the name of the method as the key
# and true as the value. This makes it possible to do O(1) lookups in respond_to? to check if a given method for attribute
# is available.
def column_methods_hash #:nodoc:
@dynamic_methods_hash ||= column_names.each_with_object(Hash.new(false)) do |attr, methods|
attr_name = attr.to_s
methods[attr.to_sym] = attr_name
methods["#{attr}=".to_sym] = attr_name
methods["#{attr}?".to_sym] = attr_name
methods["#{attr}_before_type_cast".to_sym] = attr_name
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
# 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) if table_exists?
@arel_engine = nil
@column_defaults = nil
@column_names = nil
@columns = nil
@columns_hash = nil
@column_types = nil
@content_columns = nil
@dynamic_methods_hash = nil
@inheritance_column = nil unless defined?(@explicit_inheritance_column) && @explicit_inheritance_column
@relation = nil
end
# This is a hook for use by modules that need to do extra stuff to
# attributes when they are initialized. (e.g. attribute
# serialization)
def initialize_attributes(attributes, options = {}) #:nodoc:
attributes
end
private
# 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)}#{table_name_suffix}"
else
# STI subclasses always use their superclass' table.
base.table_name
end
end
end
end
end
