module Sequel
class Model
# Associations are used in order to specify relationships between model classes
# that reflect relations between tables in the database using foreign keys.
module Associations
# Map of association type symbols to association reflection classes.
ASSOCIATION_TYPES = {}
# Set an empty association reflection hash in the model
def self.apply(model)
model.instance_variable_set(:@association_reflections, {})
end
# AssociationReflection is a Hash subclass that keeps information on Sequel::Model associations. It
# provides methods to reduce internal code duplication. It should not
# be instantiated by the user.
class AssociationReflection < Hash
include Sequel::Inflections
# Name symbol for the _add internal association method
def _add_method
:"_add_#{singularize(self[:name])}"
end
# Name symbol for the _dataset association method
def _dataset_method
:"_#{self[:name]}_dataset"
end
# Name symbol for the _remove_all internal association method
def _remove_all_method
:"_remove_all_#{self[:name]}"
end
# Name symbol for the _remove internal association method
def _remove_method
:"_remove_#{singularize(self[:name])}"
end
# Name symbol for the _setter association method
def _setter_method
:"_#{self[:name]}="
end
# Name symbol for the add association method
def add_method
:"add_#{singularize(self[:name])}"
end
# Name symbol for association method, the same as the name of the association.
def association_method
self[:name]
end
# The class associated to the current model class via this association
def associated_class
self[:class] ||= constantize(self[:class_name])
end
# Whether this association can have associated objects, given the current
# object. Should be false if obj cannot have associated objects because
# the necessary key columns are NULL.
def can_have_associated_objects?(obj)
true
end
# Name symbol for the dataset association method
def dataset_method
:"#{self[:name]}_dataset"
end
# Name symbol for the _helper internal association method
def dataset_helper_method
:"_#{self[:name]}_dataset_helper"
end
# Whether the dataset needs a primary key to function, true by default.
def dataset_need_primary_key?
true
end
# By default associations do not need to select a key in an associated table
# to eagerly load.
def eager_loading_use_associated_key?
false
end
# Whether to eagerly graph a lazy dataset, true by default. If this
# is false, the association won't respect the :eager_graph option
# when loading the association for a single record.
def eager_graph_lazy_dataset?
true
end
# Whether the associated object needs a primary key to be added/removed,
# false by default.
def need_associated_primary_key?
false
end
# Returns the reciprocal association variable, if one exists. The reciprocal
# association is the association in the associated class that is the opposite
# of the current association. For example, Album.many_to_one :artist and
# Artist.one_to_many :albums are reciprocal associations. This information is
# to populate reciprocal associations. For example, when you do this_artist.add_album(album)
# it sets album.artist to this_artist.
def reciprocal
return self[:reciprocal] if include?(:reciprocal)
r_types = Array(reciprocal_type)
keys = self[:keys]
associated_class.all_association_reflections.each do |assoc_reflect|
if r_types.include?(assoc_reflect[:type]) && assoc_reflect[:keys] == keys && assoc_reflect.associated_class == self[:model]
self[:reciprocal_type] = assoc_reflect[:type]
return self[:reciprocal] = assoc_reflect[:name]
end
end
self[:reciprocal] = nil
end
# Whether the reciprocal of this association returns an array of objects instead of a single object,
# true by default.
def reciprocal_array?
true
end
# Name symbol for the remove_all_ association method
def remove_all_method
:"remove_all_#{self[:name]}"
end
# Whether associated objects need to be removed from the association before
# being destroyed in order to preserve referential integrity.
def remove_before_destroy?
true
end
# Name symbol for the remove_ association method
def remove_method
:"remove_#{singularize(self[:name])}"
end
# Whether to check that an object to be disassociated is already associated to this object, false by default.
def remove_should_check_existing?
false
end
# Whether this association returns an array of objects instead of a single object,
# true by default.
def returns_array?
true
end
# The columns to select when loading the association.
def select
self[:select]
end
# Whether to set the reciprocal association to self when loading associated
# records, false by default.
def set_reciprocal_to_self?
false
end
# Name symbol for the setter association method
def setter_method
:"#{self[:name]}="
end
end
class ManyToOneAssociationReflection < AssociationReflection
ASSOCIATION_TYPES[:many_to_one] = self
# many_to_one associations can only have associated objects if none of
# the :keys options have a nil value.
def can_have_associated_objects?(obj)
!self[:keys].any?{|k| obj.send(k).nil?}
end
# Whether the dataset needs a primary key to function, false for many_to_one associations.
def dataset_need_primary_key?
false
end
# Default foreign key name symbol for foreign key in current model's table that points to
# the given association's table's primary key.
def default_key
:"#{self[:name]}_id"
end
# Whether to eagerly graph a lazy dataset, true for many_to_one associations
# only if the key is nil.
def eager_graph_lazy_dataset?
self[:key].nil?
end
# The key to use for the key hash when eager loading
def eager_loader_key
self[:eager_loader_key] ||= self[:key]
end
# The column(s) in the associated table that the key in the current table references (either a symbol or an array).
def primary_key
self[:primary_key] ||= associated_class.primary_key
end
# The columns in the associated table that the key in the current table references (always an array).
def primary_keys
self[:primary_keys] ||= Array(primary_key)
end
alias associated_object_keys primary_keys
# True only if the reciprocal is a one_to_many association.
def reciprocal_array?
!set_reciprocal_to_self?
end
# Whether this association returns an array of objects instead of a single object,
# false for a many_to_one association.
def returns_array?
false
end
# True only if the reciprocal is a one_to_one association.
def set_reciprocal_to_self?
reciprocal
self[:reciprocal_type] == :one_to_one
end
private
# The reciprocal type of a many_to_one association is either
# a one_to_many or a one_to_one association.
def reciprocal_type
self[:reciprocal_type] ||= [:one_to_many, :one_to_one]
end
end
class OneToManyAssociationReflection < AssociationReflection
ASSOCIATION_TYPES[:one_to_many] = self
# The keys in the associated model's table related to this association
def associated_object_keys
self[:keys]
end
# one_to_many associations can only have associated objects if none of
# the :keys options have a nil value.
def can_have_associated_objects?(obj)
!self[:primary_keys].any?{|k| obj.send(k).nil?}
end
# Default foreign key name symbol for key in associated table that points to
# current table's primary key.
def default_key
:"#{underscore(demodulize(self[:model].name))}_id"
end
# The key to use for the key hash when eager loading
def eager_loader_key
self[:eager_loader_key] ||= primary_key
end
# The column in the current table that the key in the associated table references.
def primary_key
self[:primary_key] ||= self[:model].primary_key
end
# Whether the reciprocal of this association returns an array of objects instead of a single object,
# false for a one_to_many association.
def reciprocal_array?
false
end
# Destroying one_to_many associated objects automatically deletes the foreign key.
def remove_before_destroy?
false
end
# The one_to_many association needs to check that an object to be removed already is associated.
def remove_should_check_existing?
true
end
# One to many associations set the reciprocal to self when loading associated records.
def set_reciprocal_to_self?
true
end
private
# The reciprocal type of a one_to_many association is a many_to_one association.
def reciprocal_type
:many_to_one
end
end
class OneToOneAssociationReflection < OneToManyAssociationReflection
ASSOCIATION_TYPES[:one_to_one] = self
# one_to_one associations return a single object, not an array
def returns_array?
false
end
end
class ManyToManyAssociationReflection < AssociationReflection
ASSOCIATION_TYPES[:many_to_many] = self
# The alias to use for the associated key when eagerly loading
def associated_key_alias
self[:left_key_alias]
end
# The column to use for the associated key when eagerly loading
def associated_key_column
self[:left_key]
end
# The table containing the column to use for the associated key when eagerly loading
def associated_key_table
self[:associated_key_table] ||= (
syms = associated_class.dataset.split_alias(self[:join_table]);
syms[1] || syms[0])
end
# Alias of right_primary_keys
def associated_object_keys
right_primary_keys
end
# many_to_many associations can only have associated objects if none of
# the :left_primary_keys options have a nil value.
def can_have_associated_objects?(obj)
!self[:left_primary_keys].any?{|k| obj.send(k).nil?}
end
# The default associated key alias(es) to use when eager loading
# associations via eager.
def default_associated_key_alias
self[:uses_left_composite_keys] ? (0...self[:left_keys].length).map{|i| :"x_foreign_key_#{i}_x"} : :x_foreign_key_x
end
# Default name symbol for the join table.
def default_join_table
[self[:class_name], self[:model].name].map{|i| underscore(pluralize(demodulize(i)))}.sort.join('_').to_sym
end
# Default foreign key name symbol for key in join table that points to
# current table's primary key (or :left_primary_key column).
def default_left_key
:"#{underscore(demodulize(self[:model].name))}_id"
end
# Default foreign key name symbol for foreign key in join table that points to
# the association's table's primary key (or :right_primary_key column).
def default_right_key
:"#{singularize(self[:name])}_id"
end
# The key to use for the key hash when eager loading
def eager_loader_key
self[:eager_loader_key] ||= self[:left_primary_key]
end
# many_to_many associations need to select a key in an associated table to eagerly load
def eager_loading_use_associated_key?
true
end
# Whether the associated object needs a primary key to be added/removed,
# true for many_to_many associations.
def need_associated_primary_key?
true
end
# Returns the reciprocal association symbol, if one exists.
def reciprocal
return self[:reciprocal] if include?(:reciprocal)
left_keys = self[:left_keys]
right_keys = self[:right_keys]
join_table = self[:join_table]
associated_class.all_association_reflections.each do |assoc_reflect|
if assoc_reflect[:type] == :many_to_many && assoc_reflect[:left_keys] == right_keys &&
assoc_reflect[:right_keys] == left_keys && assoc_reflect[:join_table] == join_table &&
assoc_reflect.associated_class == self[:model]
return self[:reciprocal] = assoc_reflect[:name]
end
end
self[:reciprocal] = nil
end
# The primary key column(s) to use in the associated table (can be symbol or array).
def right_primary_key
self[:right_primary_key] ||= associated_class.primary_key
end
# The primary key columns to use in the associated table (always array).
def right_primary_keys
self[:right_primary_keys] ||= Array(right_primary_key)
end
# The columns to select when loading the association, associated_class.table_name.* by default.
def select
return self[:select] if include?(:select)
self[:select] ||= Sequel::SQL::ColumnAll.new(associated_class.table_name)
end
end
# This module contains methods added to all association datasets
module AssociationDatasetMethods
# The model object that created the association dataset
attr_accessor :model_object
# The association reflection related to the association dataset
attr_accessor :association_reflection
end
# Each kind of association adds a number of instance methods to the model class which
# are specialized according to the association type and optional parameters
# given in the definition. Example:
#
# class Project < Sequel::Model
# many_to_one :portfolio
# # or: one_to_one :portfolio
# one_to_many :milestones
# # or: many_to_many :milestones
# end
#
# The project class now has the following instance methods:
# portfolio :: Returns the associated portfolio.
# portfolio=(obj) :: Sets the associated portfolio to the object,
# but the change is not persisted until you save the record (for many_to_one associations).
# portfolio_dataset :: Returns a dataset that would return the associated
# portfolio, only useful in fairly specific circumstances.
# milestones :: Returns an array of associated milestones
# add_milestone(obj) :: Associates the passed milestone with this object.
# remove_milestone(obj) :: Removes the association with the passed milestone.
# remove_all_milestones :: Removes associations with all associated milestones.
# milestones_dataset :: Returns a dataset that would return the associated
# milestones, allowing for further filtering/limiting/etc.
#
# If you want to override the behavior of the add_/remove_/remove_all_/ methods
# or the association setter method, there are private instance methods created that are prepended
# with an underscore (e.g. _add_milestone or _portfolio=). The private instance methods can be
# easily overridden, but you shouldn't override the public instance methods without
# calling super, as they deal with callbacks and caching.
#
# By default the classes for the associations are inferred from the association
# name, so for example the Project#portfolio will return an instance of
# Portfolio, and Project#milestones will return an array of Milestone
# instances. You can use the :class option to change which class is used.
#
# Association definitions are also reflected by the class, e.g.:
#
# Project.associations
# => [:portfolio, :milestones]
# Project.association_reflection(:portfolio)
# => {:type => :many_to_one, :name => :portfolio, ...}
#
# For a more in depth general overview, as well as a reference guide,
# see the {Association Basics guide}[link:files/doc/association_basics_rdoc.html].
# For examples of advanced usage, see the {Advanced Associations guide}[link:files/doc/advanced_associations_rdoc.html].
module ClassMethods
# All association reflections defined for this model (default: {}).
attr_reader :association_reflections
# Array of all association reflections for this model class
def all_association_reflections
association_reflections.values
end
# Associates a related model with the current model. The following types are
# supported:
#
# * :many_to_one - Foreign key in current model's table points to
# associated model's primary key. Each associated model object can
# be associated with more than one current model objects. Each current
# model object can be associated with only one associated model object.
# * :one_to_many - Foreign key in associated model's table points to this
# model's primary key. Each current model object can be associated with
# more than one associated model objects. Each associated model object
# can be associated with only one current model object.
# * :one_to_one - Similar to one_to_many in terms of foreign keys, but
# only one object is associated to the current object through the
# association. The methods created are similar to many_to_one, except
# that the one_to_one setter method saves the passed object.
# * :many_to_many - A join table is used that has a foreign key that points
# to this model's primary key and a foreign key that points to the
# associated model's primary key. Each current model object can be
# associated with many associated model objects, and each associated
# model object can be associated with many current model objects.
#
# The following options can be supplied:
# * *ALL types*:
# - :after_add - Symbol, Proc, or array of both/either specifying a callback to call
# after a new item is added to the association.
# - :after_load - Symbol, Proc, or array of both/either specifying a callback to call
# after the associated record(s) have been retrieved from the database. Not called
# when eager loading via eager_graph, but called when eager loading via eager.
# - :after_remove - Symbol, Proc, or array of both/either specifying a callback to call
# after an item is removed from the association.
# - :after_set - Symbol, Proc, or array of both/either specifying a callback to call
# after an item is set using the association setter method.
# - :allow_eager - If set to false, you cannot load the association eagerly
# via eager or eager_graph
# - :before_add - Symbol, Proc, or array of both/either specifying a callback to call
# before a new item is added to the association.
# - :before_remove - Symbol, Proc, or array of both/either specifying a callback to call
# before an item is removed from the association.
# - :before_set - Symbol, Proc, or array of both/either specifying a callback to call
# before an item is set using the association setter method.
# - :cartesian_product_number - the number of joins completed by this association that could cause more
# than one row for each row in the current table (default: 0 for many_to_one and one_to_one associations,
# 1 for one_to_many and many_to_many associations).
# - :class - The associated class or its name. If not
# given, uses the association's name, which is camelized (and
# singularized unless the type is :many_to_one or :one_to_one)
# - :clone - Merge the current options and block into the options and block used in defining
# the given association. Can be used to DRY up a bunch of similar associations that
# all share the same options such as :class and :key, while changing the order and block used.
# - :conditions - The conditions to use to filter the association, can be any argument passed to filter.
# - :dataset - A proc that is instance_evaled to get the base dataset
# to use for the _dataset method (before the other options are applied).
# - :distinct - Use the DISTINCT clause when selecting associating object, both when
# lazy loading and eager loading via .eager (but not when using .eager_graph).
# - :eager - The associations to eagerly load via +eager+ when loading the associated object(s).
# - :eager_block - If given, use the block instead of the default block when
# eagerly loading. To not use a block when eager loading (when one is used normally),
# set to nil.
# - :eager_graph - The associations to eagerly load via +eager_graph+ when loading the associated object(s).
# - :eager_grapher - A proc to use to implement eager loading via +eager_graph+, overriding the default.
# Takes three arguments, a dataset, an alias to use for the table to graph for this association,
# and the alias that was used for the current table (since you can cascade associations),
# Should return a copy of the dataset with the association graphed into it.
# - :eager_loader - A proc to use to implement eager loading, overriding the default. Takes one or three arguments.
# If three arguments, the first should be a key hash (used solely to enhance performance), the second an array of records,
# and the third a hash of dependent associations. If one argument, is passed a hash with keys :key_hash,
# :rows, and :associations, corresponding to the three arguments, and an additional key :self, which is
# the dataset doing the eager loading. In the proc, the associated records should
# be queried from the database and the associations cache for each
# record should be populated.
# - :eager_loader_key - A symbol for the key column to use to populate the key hash
# for the eager loader.
# - :extend - A module or array of modules to extend the dataset with.
# - :graph_block - The block to pass to join_table when eagerly loading
# the association via +eager_graph+.
# - :graph_conditions - The additional conditions to use on the SQL join when eagerly loading
# the association via +eager_graph+. Should be a hash or an array of two element arrays. If not
# specified, the :conditions option is used if it is a hash or array of two element arrays.
# - :graph_join_type - The type of SQL join to use when eagerly loading the association via
# eager_graph. Defaults to :left_outer.
# - :graph_only_conditions - The conditions to use on the SQL join when eagerly loading
# the association via +eager_graph+, instead of the default conditions specified by the
# foreign/primary keys. This option causes the :graph_conditions option to be ignored.
# - :graph_select - A column or array of columns to select from the associated table
# when eagerly loading the association via +eager_graph+. Defaults to all
# columns in the associated table.
# - :limit - Limit the number of records to the provided value. Use
# an array with two elements for the value to specify a limit (first element) and an offset (second element).
# - :methods_module - The module that methods the association creates will be placed into. Defaults
# to the module containing the model's columns.
# - :order - the column(s) by which to order the association dataset. Can be a
# singular column symbol or an array of column symbols.
# - :order_eager_graph - Whether to add the association's order to the graphed dataset's order when graphing
# via +eager_graph+. Defaults to true, so set to false to disable.
# - :read_only - Do not add a setter method (for many_to_one or one_to_one associations),
# or add_/remove_/remove_all_ methods (for one_to_many and many_to_many associations).
# - :reciprocal - the symbol name of the reciprocal association,
# if it exists. By default, Sequel will try to determine it by looking at the
# associated model's assocations for a association that matches
# the current association's key(s). Set to nil to not use a reciprocal.
# - :select - the columns to select. Defaults to the associated class's
# table_name.* in a many_to_many association, which means it doesn't include the attributes from the
# join table. If you want to include the join table attributes, you can
# use this option, but beware that the join table attributes can clash with
# attributes from the model table, so you should alias any attributes that have
# the same name in both the join table and the associated table.
# - :validate - Set to false to not validate when implicitly saving any associated object.
# * :many_to_one:
# - :key - foreign_key in current model's table that references
# associated model's primary key, as a symbol. Defaults to :"#{name}_id". Can use an
# array of symbols for a composite key association.
# - :primary_key - column in the associated table that :key option references, as a symbol.
# Defaults to the primary key of the associated table. Can use an
# array of symbols for a composite key association.
# * :one_to_many and :one_to_one:
# - :key - foreign key in associated model's table that references
# current model's primary key, as a symbol. Defaults to
# :"#{self.name.underscore}_id". Can use an
# array of symbols for a composite key association.
# - :primary_key - column in the current table that :key option references, as a symbol.
# Defaults to primary key of the current table. Can use an
# array of symbols for a composite key association.
# * :many_to_many:
# - :graph_join_table_block - The block to pass to +join_table+ for
# the join table when eagerly loading the association via +eager_graph+.
# - :graph_join_table_conditions - The additional conditions to use on the SQL join for
# the join table when eagerly loading the association via +eager_graph+. Should be a hash
# or an array of two element arrays.
# - :graph_join_table_join_type - The type of SQL join to use for the join table when eagerly
# loading the association via +eager_graph+. Defaults to the :graph_join_type option or
# :left_outer.
# - :graph_join_table_only_conditions - The conditions to use on the SQL join for the join
# table when eagerly loading the association via +eager_graph+, instead of the default
# conditions specified by the foreign/primary keys. This option causes the
# :graph_join_table_conditions option to be ignored.
# - :join_table - name of table that includes the foreign keys to both
# the current model and the associated model, as a symbol. Defaults to the name
# of current model and name of associated model, pluralized,
# underscored, sorted, and joined with '_'.
# - :join_table_block - proc that can be used to modify the dataset used in the add/remove/remove_all
# methods. Should accept a dataset argument and return a modified dataset if present.
# - :left_key - foreign key in join table that points to current model's
# primary key, as a symbol. Defaults to :"#{self.name.underscore}_id".
# Can use an array of symbols for a composite key association.
# - :left_primary_key - column in current table that :left_key points to, as a symbol.
# Defaults to primary key of current table. Can use an
# array of symbols for a composite key association.
# - :right_key - foreign key in join table that points to associated
# model's primary key, as a symbol. Defaults to Defaults to :"#{name.to_s.singularize}_id".
# Can use an array of symbols for a composite key association.
# - :right_primary_key - column in associated table that :right_key points to, as a symbol.
# Defaults to primary key of the associated table. Can use an
# array of symbols for a composite key association.
# - :uniq - Adds a after_load callback that makes the array of objects unique.
def associate(type, name, opts = {}, &block)
raise(Error, 'one_to_many association type with :one_to_one option removed, used one_to_one association type') if opts[:one_to_one] && type == :one_to_many
raise(Error, 'invalid association type') unless assoc_class = ASSOCIATION_TYPES[type]
raise(Error, 'Model.associate name argument must be a symbol') unless Symbol === name
raise(Error, ':eager_loader option must have an arity of 1 or 3') if opts[:eager_loader] && ![1, 3].include?(opts[:eager_loader].arity)
# dup early so we don't modify opts
orig_opts = opts.dup
orig_opts = association_reflection(opts[:clone])[:orig_opts].merge(orig_opts) if opts[:clone]
opts = orig_opts.merge(:type => type, :name => name, :cache => true, :model => self)
opts[:block] = block if block
opts = assoc_class.new.merge!(opts)
opts[:eager_block] = block unless opts.include?(:eager_block)
opts[:graph_join_type] ||= :left_outer
opts[:order_eager_graph] = true unless opts.include?(:order_eager_graph)
conds = opts[:conditions]
opts[:graph_conditions] = conds if !opts.include?(:graph_conditions) and Sequel.condition_specifier?(conds)
opts[:graph_conditions] = opts.fetch(:graph_conditions, []).to_a
opts[:graph_select] = Array(opts[:graph_select]) if opts[:graph_select]
[:before_add, :before_remove, :after_add, :after_remove, :after_load, :before_set, :after_set, :extend].each do |cb_type|
opts[cb_type] = Array(opts[cb_type])
end
late_binding_class_option(opts, opts.returns_array? ? singularize(name) : name)
send(:"def_#{type}", opts)
orig_opts.delete(:clone)
orig_opts.merge!(:class_name=>opts[:class_name], :class=>opts[:class], :block=>block)
opts[:orig_opts] = orig_opts
# don't add to association_reflections until we are sure there are no errors
association_reflections[name] = opts
end
# The association reflection hash for the association of the given name.
def association_reflection(name)
association_reflections[name]
end
# Array of association name symbols
def associations
association_reflections.keys
end
# Modify and return eager loading dataset based on association options.
def eager_loading_dataset(opts, ds, select, associations, eager_options={})
ds = ds.select(*select) if select
if c = opts[:conditions]
ds = (c.is_a?(Array) && !Sequel.condition_specifier?(c)) ? ds.filter(*c) : ds.filter(c)
end
ds = ds.order(*opts[:order]) if opts[:order]
ds = ds.eager(opts[:eager]) if opts[:eager]
ds = ds.distinct if opts[:distinct]
if opts[:eager_graph]
ds = ds.eager_graph(opts[:eager_graph])
ds = ds.add_graph_aliases(opts.associated_key_alias=>[opts.associated_class.table_name, opts.associated_key_alias, SQL::QualifiedIdentifier.new(opts.associated_key_table, opts.associated_key_column)]) if opts.eager_loading_use_associated_key?
elsif opts.eager_loading_use_associated_key?
ds = if opts[:uses_left_composite_keys]
t = opts.associated_key_table
ds.select_more(*opts.associated_key_alias.zip(opts.associated_key_column).map{|a, c| SQL::AliasedExpression.new(SQL::QualifiedIdentifier.new(t, c), a)})
else
ds.select_more(SQL::AliasedExpression.new(SQL::QualifiedIdentifier.new(opts.associated_key_table, opts.associated_key_column), opts.associated_key_alias))
end
end
ds = ds.eager(associations) unless Array(associations).empty?
ds = opts[:eager_block].call(ds) if opts[:eager_block]
ds
end
# Copy the association reflections to the subclass
def inherited(subclass)
super
subclass.instance_variable_set(:@association_reflections, @association_reflections.dup)
end
# Shortcut for adding a many_to_many association, see associate
def many_to_many(name, opts={}, &block)
associate(:many_to_many, name, opts, &block)
end
# Shortcut for adding a many_to_one association, see associate
def many_to_one(name, opts={}, &block)
associate(:many_to_one, name, opts, &block)
end
# Shortcut for adding a one_to_many association, see associate
def one_to_many(name, opts={}, &block)
associate(:one_to_many, name, opts, &block)
end
# Shortcut for adding a one_to_one association, see associate.
def one_to_one(name, opts={}, &block)
associate(:one_to_one, name, opts, &block)
end
private
# The module to use for the association's methods. Defaults to
# the overridable_methods_module.
def association_module(opts={})
opts.fetch(:methods_module, overridable_methods_module)
end
# Add a method to the module included in the class, so the method
# can be easily overridden in the class itself while allowing for
# super to be called.
def association_module_def(name, opts={}, &block)
association_module(opts).module_eval{define_method(name, &block)}
end
# Add a private method to the module included in the class.
def association_module_private_def(name, opts={}, &block)
association_module_def(name, opts, &block)
association_module(opts).send(:private, name)
end
# Add the add_ instance method
def def_add_method(opts)
association_module_def(opts.add_method, opts){|o,*args| add_associated_object(opts, o, *args)}
end
# Adds the association dataset methods to the association methods module.
def def_association_dataset_methods(opts)
# If a block is given, define a helper method for it, because it takes
# an argument. This is unnecessary in Ruby 1.9, as that has instance_exec.
association_module_private_def(opts.dataset_helper_method, opts, &opts[:block]) if opts[:block]
association_module_private_def(opts._dataset_method, opts, &opts[:dataset])
association_module_def(opts.dataset_method, opts){_dataset(opts)}
def_association_method(opts)
end
# Adds the association method to the association methods module.
def def_association_method(opts)
association_module_def(opts.association_method, opts){|*reload| load_associated_objects(opts, reload[0])}
end
# Configures many_to_many association reflection and adds the related association methods
def def_many_to_many(opts)
name = opts[:name]
model = self
left = (opts[:left_key] ||= opts.default_left_key)
lcks = opts[:left_keys] = Array(left)
right = (opts[:right_key] ||= opts.default_right_key)
rcks = opts[:right_keys] = Array(right)
left_pk = (opts[:left_primary_key] ||= self.primary_key)
lcpks = opts[:left_primary_keys] = Array(left_pk)
raise(Error, "mismatched number of left composite keys: #{lcks.inspect} vs #{lcpks.inspect}") unless lcks.length == lcpks.length
if opts[:right_primary_key]
rcpks = Array(opts[:right_primary_key])
raise(Error, "mismatched number of right composite keys: #{rcks.inspect} vs #{rcpks.inspect}") unless rcks.length == rcpks.length
end
uses_lcks = opts[:uses_left_composite_keys] = lcks.length > 1
uses_rcks = opts[:uses_right_composite_keys] = rcks.length > 1
opts[:cartesian_product_number] ||= 1
join_table = (opts[:join_table] ||= opts.default_join_table)
left_key_alias = opts[:left_key_alias] ||= opts.default_associated_key_alias
graph_jt_conds = opts[:graph_join_table_conditions] = opts.fetch(:graph_join_table_conditions, []).to_a
opts[:graph_join_table_join_type] ||= opts[:graph_join_type]
opts[:after_load].unshift(:array_uniq!) if opts[:uniq]
opts[:dataset] ||= proc{opts.associated_class.inner_join(join_table, rcks.zip(opts.right_primary_keys) + lcks.zip(lcpks.map{|k| send(k)}))}
database = db
opts[:eager_loader] ||= proc do |eo|
h = eo[:key_hash][left_pk]
eo[:rows].each{|object| object.associations[name] = []}
r = uses_rcks ? rcks.zip(opts.right_primary_keys) : [[right, opts.right_primary_key]]
l = uses_lcks ? [[lcks.map{|k| SQL::QualifiedIdentifier.new(join_table, k)}, h.keys]] : [[left, h.keys]]
model.eager_loading_dataset(opts, opts.associated_class.inner_join(join_table, r + l), Array(opts.select), eo[:associations], eo).all do |assoc_record|
hash_key = if uses_lcks
left_key_alias.map{|k| assoc_record.values.delete(k)}
else
assoc_record.values.delete(left_key_alias)
end
next unless objects = h[hash_key]
objects.each{|object| object.associations[name].push(assoc_record)}
end
end
join_type = opts[:graph_join_type]
select = opts[:graph_select]
use_only_conditions = opts.include?(:graph_only_conditions)
only_conditions = opts[:graph_only_conditions]
conditions = opts[:graph_conditions]
graph_block = opts[:graph_block]
use_jt_only_conditions = opts.include?(:graph_join_table_only_conditions)
jt_only_conditions = opts[:graph_join_table_only_conditions]
jt_join_type = opts[:graph_join_table_join_type]
jt_graph_block = opts[:graph_join_table_block]
opts[:eager_grapher] ||= proc do |ds, assoc_alias, table_alias|
ds = ds.graph(join_table, use_jt_only_conditions ? jt_only_conditions : lcks.zip(lcpks) + graph_jt_conds, :select=>false, :table_alias=>ds.unused_table_alias(join_table), :join_type=>jt_join_type, :implicit_qualifier=>table_alias, :from_self_alias=>ds.opts[:eager_graph][:master], &jt_graph_block)
ds.graph(opts.associated_class, use_only_conditions ? only_conditions : opts.right_primary_keys.zip(rcks) + conditions, :select=>select, :table_alias=>assoc_alias, :join_type=>join_type, &graph_block)
end
def_association_dataset_methods(opts)
return if opts[:read_only]
association_module_private_def(opts._add_method, opts) do |o|
h = {}
lcks.zip(lcpks).each{|k, pk| h[k] = send(pk)}
rcks.zip(opts.right_primary_keys).each{|k, pk| h[k] = o.send(pk)}
_join_table_dataset(opts).insert(h)
end
association_module_private_def(opts._remove_method, opts) do |o|
_join_table_dataset(opts).filter(lcks.zip(lcpks.map{|k| send(k)}) + rcks.zip(opts.right_primary_keys.map{|k| o.send(k)})).delete
end
association_module_private_def(opts._remove_all_method, opts) do
_join_table_dataset(opts).filter(lcks.zip(lcpks.map{|k| send(k)})).delete
end
def_add_method(opts)
def_remove_methods(opts)
end
# Configures many_to_one association reflection and adds the related association methods
def def_many_to_one(opts)
name = opts[:name]
model = self
opts[:key] = opts.default_key unless opts.include?(:key)
key = opts[:key]
cks = opts[:keys] = Array(opts[:key])
if opts[:primary_key]
cpks = Array(opts[:primary_key])
raise(Error, "mismatched number of composite keys: #{cks.inspect} vs #{cpks.inspect}") unless cks.length == cpks.length
end
uses_cks = opts[:uses_composite_keys] = cks.length > 1
opts[:cartesian_product_number] ||= 0
opts[:dataset] ||= proc do
klass = opts.associated_class
klass.filter(opts.primary_keys.map{|k| SQL::QualifiedIdentifier.new(klass.table_name, k)}.zip(cks.map{|k| send(k)}))
end
opts[:eager_loader] ||= proc do |eo|
h = eo[:key_hash][key]
keys = h.keys
# Default the cached association to nil, so any object that doesn't have it
# populated will have cached the negative lookup.
eo[:rows].each{|object| object.associations[name] = nil}
# Skip eager loading if no objects have a foreign key for this association
unless keys.empty?
klass = opts.associated_class
model.eager_loading_dataset(opts, klass.filter(uses_cks ? {opts.primary_keys.map{|k| SQL::QualifiedIdentifier.new(klass.table_name, k)}=>keys} : {SQL::QualifiedIdentifier.new(klass.table_name, opts.primary_key)=>keys}), opts.select, eo[:associations], eo).all do |assoc_record|
hash_key = uses_cks ? opts.primary_keys.map{|k| assoc_record.send(k)} : assoc_record.send(opts.primary_key)
next unless objects = h[hash_key]
objects.each{|object| object.associations[name] = assoc_record}
end
end
end
join_type = opts[:graph_join_type]
select = opts[:graph_select]
use_only_conditions = opts.include?(:graph_only_conditions)
only_conditions = opts[:graph_only_conditions]
conditions = opts[:graph_conditions]
graph_block = opts[:graph_block]
opts[:eager_grapher] ||= proc do |ds, assoc_alias, table_alias|
ds.graph(opts.associated_class, use_only_conditions ? only_conditions : opts.primary_keys.zip(cks) + conditions, :select=>select, :table_alias=>assoc_alias, :join_type=>join_type, :implicit_qualifier=>table_alias, :from_self_alias=>ds.opts[:eager_graph][:master], &graph_block)
end
def_association_dataset_methods(opts)
return if opts[:read_only]
association_module_private_def(opts._setter_method, opts){|o| cks.zip(opts.primary_keys).each{|k, pk| send(:"#{k}=", (o.send(pk) if o))}}
association_module_def(opts.setter_method, opts){|o| set_associated_object(opts, o)}
end
# Configures one_to_many and one_to_one association reflections and adds the related association methods
def def_one_to_many(opts)
one_to_one = opts[:type] == :one_to_one
name = opts[:name]
model = self
key = (opts[:key] ||= opts.default_key)
cks = opts[:keys] = Array(key)
primary_key = (opts[:primary_key] ||= self.primary_key)
cpks = opts[:primary_keys] = Array(primary_key)
raise(Error, "mismatched number of composite keys: #{cks.inspect} vs #{cpks.inspect}") unless cks.length == cpks.length
uses_cks = opts[:uses_composite_keys] = cks.length > 1
opts[:dataset] ||= proc do
klass = opts.associated_class
klass.filter(cks.map{|k| SQL::QualifiedIdentifier.new(klass.table_name, k)}.zip(cpks.map{|k| send(k)}))
end
opts[:eager_loader] ||= proc do |eo|
h = eo[:key_hash][primary_key]
if one_to_one
eo[:rows].each{|object| object.associations[name] = nil}
else
eo[:rows].each{|object| object.associations[name] = []}
end
reciprocal = opts.reciprocal
klass = opts.associated_class
model.eager_loading_dataset(opts, klass.filter(uses_cks ? {cks.map{|k| SQL::QualifiedIdentifier.new(klass.table_name, k)}=>h.keys} : {SQL::QualifiedIdentifier.new(klass.table_name, key)=>h.keys}), opts.select, eo[:associations], eo).all do |assoc_record|
hash_key = uses_cks ? cks.map{|k| assoc_record.send(k)} : assoc_record.send(key)
next unless objects = h[hash_key]
if one_to_one
objects.each do |object|
object.associations[name] = assoc_record
assoc_record.associations[reciprocal] = object if reciprocal
end
else
objects.each do |object|
object.associations[name].push(assoc_record)
assoc_record.associations[reciprocal] = object if reciprocal
end
end
end
end
join_type = opts[:graph_join_type]
select = opts[:graph_select]
use_only_conditions = opts.include?(:graph_only_conditions)
only_conditions = opts[:graph_only_conditions]
conditions = opts[:graph_conditions]
opts[:cartesian_product_number] ||= one_to_one ? 0 : 1
graph_block = opts[:graph_block]
opts[:eager_grapher] ||= proc do |ds, assoc_alias, table_alias|
ds = ds.graph(opts.associated_class, use_only_conditions ? only_conditions : cks.zip(cpks) + conditions, :select=>select, :table_alias=>assoc_alias, :join_type=>join_type, :implicit_qualifier=>table_alias, :from_self_alias=>ds.opts[:eager_graph][:master], &graph_block)
# We only load reciprocals for one_to_many associations, as other reciprocals don't make sense
ds.opts[:eager_graph][:reciprocals][assoc_alias] = opts.reciprocal
ds
end
def_association_dataset_methods(opts)
ck_nil_hash ={}
cks.each{|k| ck_nil_hash[k] = nil}
unless opts[:read_only]
validate = opts[:validate]
if one_to_one
association_module_private_def(opts._setter_method, opts) do |o|
up_ds = _apply_association_options(opts, opts.associated_class.filter(cks.zip(cpks.map{|k| send(k)})))
if o
up_ds = up_ds.exclude(o.pk_hash)
cks.zip(cpks).each{|k, pk| o.send(:"#{k}=", send(pk))}
end
checked_transaction do
up_ds.update(ck_nil_hash)
o.save(:validate=>validate) || raise(Sequel::Error, "invalid associated object, cannot save") if o
end
end
association_module_def(opts.setter_method, opts){|o| set_one_to_one_associated_object(opts, o)}
else
association_module_private_def(opts._add_method, opts) do |o|
cks.zip(cpks).each{|k, pk| o.send(:"#{k}=", send(pk))}
o.save(:validate=>validate) || raise(Sequel::Error, "invalid associated object, cannot save")
end
def_add_method(opts)
association_module_private_def(opts._remove_method, opts) do |o|
cks.each{|k| o.send(:"#{k}=", nil)}
o.save(:validate=>validate) || raise(Sequel::Error, "invalid associated object, cannot save")
end
association_module_private_def(opts._remove_all_method, opts) do
_apply_association_options(opts, opts.associated_class.filter(cks.zip(cpks.map{|k| send(k)}))).update(ck_nil_hash)
end
def_remove_methods(opts)
end
end
end
# Alias of def_one_to_many, since they share pretty much the same code.
def def_one_to_one(opts)
def_one_to_many(opts)
end
# Add the remove_ and remove_all instance methods
def def_remove_methods(opts)
association_module_def(opts.remove_method, opts){|o,*args| remove_associated_object(opts, o, *args)}
association_module_def(opts.remove_all_method, opts){|*args| remove_all_associated_objects(opts, *args)}
end
end
# Instance methods used to implement the associations support.
module InstanceMethods
# The currently cached associations. A hash with the keys being the
# association name symbols and the values being the associated object
# or nil (many_to_one), or the array of associated objects (*_to_many).
def associations
@associations ||= {}
end
# Used internally by the associations code, like pk but doesn't raise
# an Error if the model has no primary key.
def pk_or_nil
key = primary_key
key.is_a?(Array) ? key.map{|k| @values[k]} : @values[key]
end
private
# Apply the association options such as :order and :limit to the given dataset, returning a modified dataset.
def _apply_association_options(opts, ds)
ds.extend(AssociationDatasetMethods)
ds.model_object = self
ds.association_reflection = opts
opts[:extend].each{|m| ds.extend(m)}
ds = ds.select(*opts.select) if opts.select
if c = opts[:conditions]
ds = (c.is_a?(Array) && !Sequel.condition_specifier?(c)) ? ds.filter(*c) : ds.filter(c)
end
ds = ds.order(*opts[:order]) if opts[:order]
ds = ds.limit(*opts[:limit]) if opts[:limit]
ds = ds.limit(1) if !opts.returns_array? && opts[:key]
ds = ds.eager(*opts[:eager]) if opts[:eager]
ds = ds.distinct if opts[:distinct]
ds = ds.eager_graph(opts[:eager_graph]) if opts[:eager_graph] && opts.eager_graph_lazy_dataset?
ds = send(opts.dataset_helper_method, ds) if opts[:block]
ds
end
# Return an association dataset for the given association reflection
def _dataset(opts)
raise(Sequel::Error, "model object #{inspect} does not have a primary key") if opts.dataset_need_primary_key? && !pk
_apply_association_options(opts, send(opts._dataset_method))
end
# Dataset for the join table of the given many to many association reflection
def _join_table_dataset(opts)
ds = model.db.from(opts[:join_table])
opts[:join_table_block] ? opts[:join_table_block].call(ds) : ds
end
# Return the associated objects from the dataset, without callbacks, reciprocals, and caching.
def _load_associated_objects(opts)
if opts.returns_array?
opts.can_have_associated_objects?(self) ? send(opts.dataset_method).all : []
else
if opts.can_have_associated_objects?(self)
send(opts.dataset_method).all.first
end
end
end
# Clear the associations cache when refreshing
def _refresh(dataset)
associations.clear
super
end
# Add the given associated object to the given association
def add_associated_object(opts, o, *args)
klass = opts.associated_class
if o.is_a?(Hash)
o = klass.new(o)
elsif o.is_a?(Integer) || o.is_a?(String) || o.is_a?(Array)
o = klass[o]
elsif !o.is_a?(klass)
raise(Sequel::Error, "associated object #{o.inspect} not of correct type #{klass}")
end
raise(Sequel::Error, "model object #{inspect} does not have a primary key") unless pk
ensure_associated_primary_key(opts, o, *args)
return if run_association_callbacks(opts, :before_add, o) == false
send(opts._add_method, o, *args)
if array = associations[opts[:name]] and !array.include?(o)
array.push(o)
end
add_reciprocal_object(opts, o)
run_association_callbacks(opts, :after_add, o)
o
end
# Add/Set the current object to/as the given object's reciprocal association.
def add_reciprocal_object(opts, o)
return unless reciprocal = opts.reciprocal
if opts.reciprocal_array?
if array = o.associations[reciprocal] and !array.include?(self)
array.push(self)
end
else
o.associations[reciprocal] = self
end
end
# Call uniq! on the given array. This is used by the :uniq option,
# and is an actual method for memory reasons.
def array_uniq!(a)
a.uniq!
end
# Save the associated object if the associated object needs a primary key
# and the associated object is new and does not have one. Raise an error if
# the object still does not have a primary key
def ensure_associated_primary_key(opts, o, *args)
if opts.need_associated_primary_key?
o.save(:validate=>opts[:validate]) if o.new?
raise(Sequel::Error, "associated object #{o.inspect} does not have a primary key") unless o.pk
end
end
# Load the associated objects using the dataset, handling callbacks, reciprocals, and caching.
def load_associated_objects(opts, reload=false)
name = opts[:name]
if associations.include?(name) and !reload
associations[name]
else
objs = _load_associated_objects(opts)
run_association_callbacks(opts, :after_load, objs)
if opts.set_reciprocal_to_self?
if opts.returns_array?
objs.each{|o| add_reciprocal_object(opts, o)}
elsif objs
add_reciprocal_object(opts, objs)
end
end
associations[name] = objs
end
end
# Remove all associated objects from the given association
def remove_all_associated_objects(opts, *args)
raise(Sequel::Error, "model object #{inspect} does not have a primary key") unless pk
send(opts._remove_all_method, *args)
ret = associations[opts[:name]].each{|o| remove_reciprocal_object(opts, o)} if associations.include?(opts[:name])
associations[opts[:name]] = []
ret
end
# Remove the given associated object from the given association
def remove_associated_object(opts, o, *args)
klass = opts.associated_class
if o.is_a?(Integer) || o.is_a?(String) || o.is_a?(Array)
o = remove_check_existing_object_from_pk(opts, o, *args)
elsif !o.is_a?(klass)
raise(Sequel::Error, "associated object #{o.inspect} not of correct type #{klass}")
elsif opts.remove_should_check_existing? && send(opts.dataset_method).filter(o.pk_hash).empty?
raise(Sequel::Error, "associated object #{o.inspect} is not currently associated to #{inspect}")
end
raise(Sequel::Error, "model object #{inspect} does not have a primary key") unless pk
raise(Sequel::Error, "associated object #{o.inspect} does not have a primary key") if opts.need_associated_primary_key? && !o.pk
return if run_association_callbacks(opts, :before_remove, o) == false
send(opts._remove_method, o, *args)
associations[opts[:name]].delete_if{|x| o === x} if associations.include?(opts[:name])
remove_reciprocal_object(opts, o)
run_association_callbacks(opts, :after_remove, o)
o
end
# Check that the object from the associated table specified by the primary key
# is currently associated to the receiver. If it is associated, return the object, otherwise
# raise an error.
def remove_check_existing_object_from_pk(opts, o, *args)
key = o
pkh = opts.associated_class.qualified_primary_key_hash(key)
raise(Sequel::Error, "no object with key(s) #{key.inspect} is currently associated to #{inspect}") unless o = send(opts.dataset_method).first(pkh)
o
end
# Remove/unset the current object from/as the given object's reciprocal association.
def remove_reciprocal_object(opts, o)
return unless reciprocal = opts.reciprocal
if opts.reciprocal_array?
if array = o.associations[reciprocal]
array.delete_if{|x| self === x}
end
else
o.associations[reciprocal] = nil
end
end
# Run the callback for the association with the object.
def run_association_callbacks(reflection, callback_type, object)
raise_error = raise_on_save_failure || !reflection.returns_array?
stop_on_false = [:before_add, :before_remove, :before_set].include?(callback_type)
reflection[callback_type].each do |cb|
res = case cb
when Symbol
send(cb, object)
when Proc
cb.call(self, object)
else
raise Error, "callbacks should either be Procs or Symbols"
end
if res == false and stop_on_false
raise(BeforeHookFailed, "Unable to modify association for #{inspect}: one of the #{callback_type} hooks returned false") if raise_error
return false
end
end
end
# Set the given object as the associated object for the given many_to_one association reflection
def set_associated_object(opts, o)
raise(Error, "associated object #{o.inspect} does not have a primary key") if o && !o.pk
run_association_callbacks(opts, :before_set, o)
if a = associations[opts[:name]]
remove_reciprocal_object(opts, a)
end
send(opts._setter_method, o)
associations[opts[:name]] = o
add_reciprocal_object(opts, o) if o
run_association_callbacks(opts, :after_set, o)
o
end
# Set the given object as the associated object for the given one_to_one association reflection
def set_one_to_one_associated_object(opts, o)
raise(Error, "object #{inspect} does not have a primary key") unless pk
run_association_callbacks(opts, :before_set, o)
if a = associations[opts[:name]]
remove_reciprocal_object(opts, a)
end
send(opts._setter_method, o)
associations[opts[:name]] = o
add_reciprocal_object(opts, o) if o
run_association_callbacks(opts, :after_set, o)
o
end
end
# Eager loading makes it so that you can load all associated records for a
# set of objects in a single query, instead of a separate query for each object.
#
# Two separate implementations are provided. +eager+ should be used most of the
# time, as it loads associated records using one query per association. However,
# it does not allow you the ability to filter or order based on columns in associated tables. +eager_graph+ loads
# all records in a single query using JOINs, allowing you to filter or order based on columns in associated
# tables. However, +eager_graph+ can be slower than +eager+, especially if multiple
# one_to_many or many_to_many associations are joined.
#
# You can cascade the eager loading (loading associations on associated objects)
# with no limit to the depth of the cascades. You do this by passing a hash to +eager+ or +eager_graph+
# with the keys being associations of the current model and values being
# associations of the model associated with the current model via the key.
#
# The arguments can be symbols or hashes with symbol keys (for cascaded
# eager loading). Examples:
#
# Album.eager(:artist).all
# Album.eager_graph(:artist).all
# Album.eager(:artist, :genre).all
# Album.eager_graph(:artist, :genre).all
# Album.eager(:artist).eager(:genre).all
# Album.eager_graph(:artist).eager(:genre).all
# Artist.eager(:albums=>:tracks).all
# Artist.eager_graph(:albums=>:tracks).all
# Artist.eager(:albums=>{:tracks=>:genre}).all
# Artist.eager_graph(:albums=>{:tracks=>:genre}).all
module DatasetMethods
# Add the <tt>eager!</tt> and <tt>eager_graph!</tt> mutation methods to the dataset.
def self.extended(obj)
obj.def_mutation_method(:eager, :eager_graph)
end
# The preferred eager loading method. Loads all associated records using one
# query for each association.
#
# The basic idea for how it works is that the dataset is first loaded normally.
# Then it goes through all associations that have been specified via +eager+.
# It loads each of those associations separately, then associates them back
# to the original dataset via primary/foreign keys. Due to the necessity of
# all objects being present, you need to use +all+ to use eager loading, as it
# can't work with +each+.
#
# This implementation avoids the complexity of extracting an object graph out
# of a single dataset, by building the object graph out of multiple datasets,
# one for each association. By using a separate dataset for each association,
# it avoids problems such as aliasing conflicts and creating cartesian product
# result sets if multiple one_to_many or many_to_many eager associations are requested.
#
# One limitation of using this method is that you cannot filter the dataset
# based on values of columns in an associated table, since the associations are loaded
# in separate queries. To do that you need to load all associations in the
# same query, and extract an object graph from the results of that query. If you
# need to filter based on columns in associated tables, look at +eager_graph+
# or join the tables you need to filter on manually.
#
# Each association's order, if defined, is respected. Eager also works
# on a limited dataset, but does not use any :limit options for associations.
# If the association uses a block or has an :eager_block argument, it is used.
def eager(*associations)
opt = @opts[:eager]
opt = opt ? opt.dup : {}
associations.flatten.each do |association|
case association
when Symbol
check_association(model, association)
opt[association] = nil
when Hash
association.keys.each{|assoc| check_association(model, assoc)}
opt.merge!(association)
else raise(Sequel::Error, 'Associations must be in the form of a symbol or hash')
end
end
clone(:eager=>opt)
end
# The secondary eager loading method. Loads all associations in a single query. This
# method should only be used if you need to filter or order based on columns in associated tables.
#
# This method builds an object graph using <tt>Dataset#graph</tt>. Then it uses the graph
# to build the associations, and finally replaces the graph with a simple array
# of model objects.
#
# Be very careful when using this with multiple one_to_many or many_to_many associations, as you can
# create large cartesian products. If you must graph multiple one_to_many and many_to_many associations,
# make sure your filters are narrow if you have a large database.
#
# Each association's order, if definied, is respected. +eager_graph+ probably
# won't work correctly on a limited dataset, unless you are
# only graphing many_to_one and one_to_one associations.
#
# Does not use the block defined for the association, since it does a single query for
# all objects. You can use the :graph_* association options to modify the SQL query.
#
# Like +eager+, you need to call +all+ on the dataset for the eager loading to work. If you just
# call +each+, you will get a normal graphed result back (a hash with table alias symbol keys and
# model object values).
def eager_graph(*associations)
ds = if @opts[:eager_graph]
self
else
# Each of the following have a symbol key for the table alias, with the following values:
# :reciprocals - the reciprocal instance variable to use for this association
# :requirements - array of requirements for this association
# :alias_association_type_map - the type of association for this association
# :alias_association_name_map - the name of the association for this association
clone(:eager_graph=>{:requirements=>{}, :master=>alias_symbol(first_source), :alias_association_type_map=>{}, :alias_association_name_map=>{}, :reciprocals=>{}, :cartesian_product_number=>0})
end
ds.eager_graph_associations(ds, model, ds.opts[:eager_graph][:master], [], *associations)
end
# Do not attempt to split the result set into associations,
# just return results as simple objects. This is useful if you
# want to use eager_graph as a shortcut to have all of the joins
# and aliasing set up, but want to do something else with the dataset.
def ungraphed
super.clone(:eager_graph=>nil)
end
protected
# Call graph on the association with the correct arguments,
# update the eager_graph data structure, and recurse into
# eager_graph_associations if there are any passed in associations
# (which would be dependencies of the current association)
#
# Arguments:
# ds :: Current dataset
# model :: Current Model
# ta :: table_alias used for the parent association
# requirements :: an array, used as a stack for requirements
# r :: association reflection for the current association
# *associations :: any associations dependent on this one
def eager_graph_association(ds, model, ta, requirements, r, *associations)
klass = r.associated_class
assoc_name = r[:name]
assoc_table_alias = ds.unused_table_alias(assoc_name)
ds = r[:eager_grapher].call(ds, assoc_table_alias, ta)
ds = ds.order_more(*qualified_expression(r[:order], assoc_table_alias)) if r[:order] and r[:order_eager_graph]
eager_graph = ds.opts[:eager_graph]
eager_graph[:requirements][assoc_table_alias] = requirements.dup
eager_graph[:alias_association_name_map][assoc_table_alias] = assoc_name
eager_graph[:alias_association_type_map][assoc_table_alias] = r.returns_array?
eager_graph[:cartesian_product_number] += r[:cartesian_product_number] || 2
ds = ds.eager_graph_associations(ds, r.associated_class, assoc_table_alias, requirements + [assoc_table_alias], *associations) unless associations.empty?
ds
end
# Check the associations are valid for the given model.
# Call eager_graph_association on each association.
#
# Arguments:
# ds :: Current dataset
# model :: Current Model
# ta :: table_alias used for the parent association
# requirements :: an array, used as a stack for requirements
# *associations :: the associations to add to the graph
def eager_graph_associations(ds, model, ta, requirements, *associations)
return ds if associations.empty?
associations.flatten.each do |association|
ds = case association
when Symbol
ds.eager_graph_association(ds, model, ta, requirements, check_association(model, association))
when Hash
association.each do |assoc, assoc_assocs|
ds = ds.eager_graph_association(ds, model, ta, requirements, check_association(model, assoc), assoc_assocs)
end
ds
else raise(Sequel::Error, 'Associations must be in the form of a symbol or hash')
end
end
ds
end
# Build associations out of the array of returned object graphs.
def eager_graph_build_associations(record_graphs)
eager_graph = @opts[:eager_graph]
master = eager_graph[:master]
requirements = eager_graph[:requirements]
alias_map = eager_graph[:alias_association_name_map]
type_map = eager_graph[:alias_association_type_map]
reciprocal_map = eager_graph[:reciprocals]
# Make dependency map hash out of requirements array for each association.
# This builds a tree of dependencies that will be used for recursion
# to ensure that all parts of the object graph are loaded into the
# appropriate subordinate association.
dependency_map = {}
# Sort the associations by requirements length, so that
# requirements are added to the dependency hash before their
# dependencies.
requirements.sort_by{|a| a[1].length}.each do |ta, deps|
if deps.empty?
dependency_map[ta] = {}
else
deps = deps.dup
hash = dependency_map[deps.shift]
deps.each do |dep|
hash = hash[dep]
end
hash[ta] = {}
end
end
# This mapping is used to make sure that duplicate entries in the
# result set are mapped to a single record. For example, using a
# single one_to_many association with 10 associated records,
# the main object will appear in the object graph 10 times.
# We map by primary key, if available, or by the object's entire values,
# if not. The mapping must be per table, so create sub maps for each table
# alias.
records_map = {master=>{}}
alias_map.keys.each{|ta| records_map[ta] = {}}
# This will hold the final record set that we will be replacing the object graph with.
records = []
record_graphs.each do |record_graph|
primary_record = record_graph[master]
key = primary_record.pk_or_nil || primary_record.values.sort_by{|x| x[0].to_s}
if cached_pr = records_map[master][key]
primary_record = cached_pr
else
records_map[master][key] = primary_record
# Only add it to the list of records to return if it is a new record
records.push(primary_record)
end
# Build all associations for the current object and it's dependencies
eager_graph_build_associations_graph(dependency_map, alias_map, type_map, reciprocal_map, records_map, primary_record, record_graph)
end
# Remove duplicate records from all associations if this graph could possibly be a cartesian product
eager_graph_make_associations_unique(records, dependency_map, alias_map, type_map) if eager_graph[:cartesian_product_number] > 1
# Replace the array of object graphs with an array of model objects
record_graphs.replace(records)
end
private
# Make sure the association is valid for this model, and return the related AssociationReflection.
def check_association(model, association)
raise(Sequel::UndefinedAssociation, "Invalid association #{association} for #{model.name}") unless reflection = model.association_reflection(association)
raise(Sequel::Error, "Eager loading is not allowed for #{model.name} association #{association}") if reflection[:allow_eager] == false
reflection
end
# Build associations for the current object. This is called recursively
# to build all dependencies.
def eager_graph_build_associations_graph(dependency_map, alias_map, type_map, reciprocal_map, records_map, current, record_graph)
return if dependency_map.empty?
# Don't clobber the cached association value for one_to_many and many_to_many associations if it has already been setup
dependency_map.keys.each do |ta|
assoc_name = alias_map[ta]
current.associations[assoc_name] = type_map[ta] ? [] : nil unless current.associations.include?(assoc_name)
end
dependency_map.each do |ta, deps|
next unless rec = record_graph[ta]
key = rec.pk_or_nil || rec.values.sort_by{|x| x[0].to_s}
if cached_rec = records_map[ta][key]
rec = cached_rec
else
records_map[ta][key] = rec
end
assoc_name = alias_map[ta]
if type_map[ta]
current.associations[assoc_name].push(rec)
if reciprocal = reciprocal_map[ta]
rec.associations[reciprocal] = current
end
else
current.associations[assoc_name] = rec
end
# Recurse into dependencies of the current object
eager_graph_build_associations_graph(deps, alias_map, type_map, reciprocal_map, records_map, rec, record_graph)
end
end
# If the result set is the result of a cartesian product, then it is possible that
# there are multiple records for each association when there should only be one.
# In that case, for each object in all associations loaded via +eager_graph+, run
# uniq! on the association to make sure no duplicate records show up.
# Note that this can cause legitimate duplicate records to be removed.
def eager_graph_make_associations_unique(records, dependency_map, alias_map, type_map)
records.each do |record|
dependency_map.each do |ta, deps|
list = record.send(alias_map[ta])
list = if type_map[ta]
list.uniq!
else
[list] if list
end
# Recurse into dependencies
eager_graph_make_associations_unique(list, deps, alias_map, type_map) if list
end
end
end
# Eagerly load all specified associations
def eager_load(a, eager_assoc=@opts[:eager])
return if a.empty?
# Key is foreign/primary key name symbol
# Value is hash with keys being foreign/primary key values (generally integers)
# and values being an array of current model objects with that
# specific foreign/primary key
key_hash = {}
# Reflections for all associations to eager load
reflections = eager_assoc.keys.collect{|assoc| model.association_reflection(assoc) || (raise Sequel::UndefinedAssociation, "Model: #{self}, Association: #{assoc}")}
# Populate keys to monitor
reflections.each{|reflection| key_hash[reflection.eager_loader_key] ||= Hash.new{|h,k| h[k] = []}}
# Associate each object with every key being monitored
a.each do |rec|
key_hash.each do |key, id_map|
case key
when Array
id_map[key.map{|k| rec[k]}] << rec if key.all?{|k| rec[k]}
when Symbol
id_map[rec[key]] << rec if rec[key]
end
end
end
reflections.each do |r|
loader = r[:eager_loader]
if loader.arity == 1
loader.call(:key_hash=>key_hash, :rows=>a, :associations=>eager_assoc[r[:name]], :self=>self)
else
loader.call(key_hash, a, eager_assoc[r[:name]])
end
a.each{|object| object.send(:run_association_callbacks, r, :after_load, object.associations[r[:name]])} unless r[:after_load].empty?
end
end
# Build associations from the graph if #eager_graph was used,
# and/or load other associations if #eager was used.
def post_load(all_records)
eager_graph_build_associations(all_records) if @opts[:eager_graph]
eager_load(all_records) if @opts[:eager]
super
end
end
end
end
end