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require "active_record/associations/join_dependency/join_part"
module ActiveRecord
module Associations
class JoinDependency # :nodoc:
class JoinAssociation < JoinPart # :nodoc:
# The reflection of the association represented
attr_reader :reflection
attr_accessor :tables
def initialize(reflection, children)
super(reflection.klass, children)
@reflection = reflection
@tables = nil
end
def match?(other)
return true if self == other
super && reflection == other.reflection
end
JoinInformation = Struct.new :joins, :binds
def join_constraints(foreign_table, foreign_klass, join_type, tables, chain)
joins = []
binds = []
tables = tables.reverse
# The chain starts with the target table, but we want to end with it here (makes
# more sense in this context), so we reverse
chain.reverse_each do |reflection|
table = tables.shift
klass = reflection.klass
join_keys = reflection.join_keys
key = join_keys.key
foreign_key = join_keys.foreign_key
constraint = build_constraint(klass, table, key, foreign_table, foreign_key)
predicate_builder = PredicateBuilder.new(TableMetadata.new(klass, table))
scope_chain_items = reflection.join_scopes(table, predicate_builder)
klass_scope = reflection.klass_join_scope(table, predicate_builder)
scope_chain_items.concat [klass_scope].compact
rel = scope_chain_items.inject(scope_chain_items.shift) do |left, right|
left.merge right
end
if rel && !rel.arel.constraints.empty?
binds += rel.bound_attributes
constraint = constraint.and rel.arel.constraints
end
if reflection.type
value = foreign_klass.base_class.name
column = klass.columns_hash[reflection.type.to_s]
binds << Relation::QueryAttribute.new(column.name, value, klass.type_for_attribute(column.name))
constraint = constraint.and klass.arel_attribute(reflection.type, table).eq(Arel::Nodes::BindParam.new)
end
joins << table.create_join(table, table.create_on(constraint), join_type)
# The current table in this iteration becomes the foreign table in the next
foreign_table, foreign_klass = table, klass
end
JoinInformation.new joins, binds
end
# Builds equality condition.
#
# Example:
#
# class Physician < ActiveRecord::Base
# has_many :appointments
# end
#
# If I execute `Physician.joins(:appointments).to_a` then
# klass # => Physician
# table # => #<Arel::Table @name="appointments" ...>
# key # => physician_id
# foreign_table # => #<Arel::Table @name="physicians" ...>
# foreign_key # => id
#
def build_constraint(klass, table, key, foreign_table, foreign_key)
constraint = table[key].eq(foreign_table[foreign_key])
if klass.finder_needs_type_condition?
constraint = table.create_and([
constraint,
klass.send(:type_condition, table)
])
end
constraint
end
def table
tables.first
end
def aliased_table_name
table.table_alias || table.name
end
end
end
end
end
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