module ActiveRecord
module Associations
module ClassMethods
class JoinDependency # :nodoc:
class JoinAssociation < JoinPart # :nodoc:
# The reflection of the association represented
attr_reader :reflection
# The JoinDependency object which this JoinAssociation exists within. This is mainly
# relevant for generating aliases which do not conflict with other joins which are
# part of the query.
attr_reader :join_dependency
# A JoinBase instance representing the active record we are joining onto.
# (So in Author.has_many :posts, the Author would be that base record.)
attr_reader :parent
# What type of join will be generated, either Arel::InnerJoin (default) or Arel::OuterJoin
attr_accessor :join_type
# These implement abstract methods from the superclass
attr_reader :aliased_prefix, :aliased_table_name
delegate :options, :through_reflection, :source_reflection, :to => :reflection
delegate :table, :table_name, :to => :parent, :prefix => true
def initialize(reflection, join_dependency, parent = nil)
reflection.check_validity!
if reflection.options[:polymorphic]
raise EagerLoadPolymorphicError.new(reflection)
end
super(reflection.klass)
@reflection = reflection
@join_dependency = join_dependency
@parent = parent
@join_type = Arel::InnerJoin
# This must be done eagerly upon initialisation because the alias which is produced
# depends on the state of the join dependency, but we want it to work the same way
# every time.
allocate_aliases
end
def ==(other)
other.class == self.class &&
other.reflection == reflection &&
other.parent == parent
end
def find_parent_in(other_join_dependency)
other_join_dependency.join_parts.detect do |join_part|
self.parent == join_part
end
end
def join_to(relation)
send("join_#{reflection.macro}_to", relation)
end
def join_relation(joining_relation)
self.join_type = Arel::OuterJoin
joining_relation.joins(self)
end
def table
@table ||= Arel::Table.new(
table_name, :as => aliased_table_name,
:engine => arel_engine, :columns => active_record.columns
)
end
# More semantic name given we are talking about associations
alias_method :target_table, :table
protected
def aliased_table_name_for(name, suffix = nil)
if @join_dependency.table_aliases[name].zero?
@join_dependency.table_aliases[name] = @join_dependency.count_aliases_from_table_joins(name)
end
if !@join_dependency.table_aliases[name].zero? # We need an alias
name = active_record.connection.table_alias_for "#{pluralize(reflection.name)}_#{parent_table_name}#{suffix}"
@join_dependency.table_aliases[name] += 1
if @join_dependency.table_aliases[name] == 1 # First time we've seen this name
# Also need to count the aliases from the table_aliases to avoid incorrect count
@join_dependency.table_aliases[name] += @join_dependency.count_aliases_from_table_joins(name)
end
table_index = @join_dependency.table_aliases[name]
name = name[0..active_record.connection.table_alias_length-3] + "_#{table_index}" if table_index > 1
else
@join_dependency.table_aliases[name] += 1
end
name
end
def pluralize(table_name)
ActiveRecord::Base.pluralize_table_names ? table_name.to_s.pluralize : table_name
end
def interpolate_sql(sql)
instance_eval("%@#{sql.gsub('@', '\@')}@", __FILE__, __LINE__)
end
private
def allocate_aliases
@aliased_prefix = "t#{ join_dependency.join_parts.size }"
@aliased_table_name = aliased_table_name_for(table_name)
if reflection.macro == :has_and_belongs_to_many
@aliased_join_table_name = aliased_table_name_for(reflection.options[:join_table], "_join")
elsif [:has_many, :has_one].include?(reflection.macro) && reflection.options[:through]
@aliased_join_table_name = aliased_table_name_for(reflection.through_reflection.klass.table_name, "_join")
end
end
def process_conditions(conditions, table_name)
Arel.sql(interpolate_sql(sanitize_sql(conditions, table_name)))
end
def join_target_table(relation, *conditions)
relation = relation.join(target_table, join_type)
# If the target table is an STI model then we must be sure to only include records of
# its type and its sub-types.
unless active_record.descends_from_active_record?
sti_column = target_table[active_record.inheritance_column]
sti_condition = sti_column.eq(active_record.sti_name)
active_record.descendants.each do |subclass|
sti_condition = sti_condition.or(sti_column.eq(subclass.sti_name))
end
conditions << sti_condition
end
# If the reflection has conditions, add them
if options[:conditions]
conditions << process_conditions(options[:conditions], aliased_table_name)
end
relation = relation.on(*conditions)
end
def join_has_and_belongs_to_many_to(relation)
join_table = Arel::Table.new(
options[:join_table], :engine => arel_engine,
:as => @aliased_join_table_name
)
fk = options[:foreign_key] || reflection.active_record.to_s.foreign_key
klass_fk = options[:association_foreign_key] || reflection.klass.to_s.foreign_key
relation = relation.join(join_table, join_type)
relation = relation.on(
join_table[fk].
eq(parent_table[reflection.active_record.primary_key])
)
join_target_table(
relation,
target_table[reflection.klass.primary_key].
eq(join_table[klass_fk])
)
end
def join_has_many_to(relation)
if reflection.options[:through]
join_has_many_through_to(relation)
elsif reflection.options[:as]
join_has_many_polymorphic_to(relation)
else
foreign_key = options[:foreign_key] || reflection.active_record.name.foreign_key
primary_key = options[:primary_key] || parent.primary_key
join_target_table(
relation,
target_table[foreign_key].
eq(parent_table[primary_key])
)
end
end
alias :join_has_one_to :join_has_many_to
def join_has_many_through_to(relation)
join_table = Arel::Table.new(
through_reflection.klass.table_name, :engine => arel_engine,
:as => @aliased_join_table_name
)
jt_conditions = []
jt_foreign_key = first_key = second_key = nil
if through_reflection.options[:as] # has_many :through against a polymorphic join
as_key = through_reflection.options[:as].to_s
jt_foreign_key = as_key + '_id'
jt_conditions <<
join_table[as_key + '_type'].
eq(parent.active_record.base_class.name)
else
jt_foreign_key = through_reflection.primary_key_name
end
case source_reflection.macro
when :has_many
second_key = options[:foreign_key] || primary_key
if source_reflection.options[:as]
first_key = "#{source_reflection.options[:as]}_id"
else
first_key = through_reflection.klass.base_class.to_s.foreign_key
end
unless through_reflection.klass.descends_from_active_record?
jt_conditions <<
join_table[through_reflection.active_record.inheritance_column].
eq(through_reflection.klass.sti_name)
end
when :belongs_to
first_key = primary_key
if reflection.options[:source_type]
second_key = source_reflection.association_foreign_key
jt_conditions <<
join_table[reflection.source_reflection.options[:foreign_type]].
eq(reflection.options[:source_type])
else
second_key = source_reflection.primary_key_name
end
end
jt_conditions <<
parent_table[parent.primary_key].
eq(join_table[jt_foreign_key])
if through_reflection.options[:conditions]
jt_conditions << process_conditions(through_reflection.options[:conditions], aliased_table_name)
end
relation = relation.join(join_table, join_type).on(*jt_conditions)
join_target_table(
relation,
target_table[first_key].eq(join_table[second_key])
)
end
def join_has_many_polymorphic_to(relation)
join_target_table(
relation,
target_table["#{reflection.options[:as]}_id"].
eq(parent_table[parent.primary_key]),
target_table["#{reflection.options[:as]}_type"].
eq(parent.active_record.base_class.name)
)
end
def join_belongs_to_to(relation)
foreign_key = options[:foreign_key] || reflection.primary_key_name
primary_key = options[:primary_key] || reflection.klass.primary_key
join_target_table(
relation,
target_table[primary_key].eq(parent_table[foreign_key])
)
end
end
end
end
end
end