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module ActiveRecord
module Associations
class JoinDependency # :nodoc:
autoload :JoinBase, 'active_record/associations/join_dependency/join_base'
autoload :JoinAssociation, 'active_record/associations/join_dependency/join_association'
attr_reader :alias_tracker, :base_klass, :join_root
def self.make_tree(associations)
hash = {}
walk_tree associations, hash
hash
end
def self.walk_tree(associations, hash)
case associations
when Symbol, String
hash[associations.to_sym] ||= {}
when Array
associations.each do |assoc|
walk_tree assoc, hash
end
when Hash
associations.each do |k,v|
cache = hash[k] ||= {}
walk_tree v, cache
end
else
raise ConfigurationError, associations.inspect
end
end
# base is the base class on which operation is taking place.
# associations is the list of associations which are joined using hash, symbol or array.
# joins is the list of all string join commnads and arel nodes.
#
# Example :
#
# class Physician < ActiveRecord::Base
# has_many :appointments
# has_many :patients, through: :appointments
# end
#
# If I execute `@physician.patients.to_a` then
# base #=> Physician
# associations #=> []
# joins #=> [#<Arel::Nodes::InnerJoin: ...]
#
# However if I execute `Physician.joins(:appointments).to_a` then
# base #=> Physician
# associations #=> [:appointments]
# joins #=> []
#
def initialize(base, associations, joins)
@base_klass = base
@join_root = JoinBase.new(base)
@alias_tracker = AliasTracker.new(base.connection, joins)
@alias_tracker.aliased_name_for(base.table_name) # Updates the count for base.table_name to 1
tree = self.class.make_tree associations
build tree, @join_root, Arel::InnerJoin
end
def reflections
join_root.drop(1).map!(&:reflection)
end
def merge_outer_joins!(other)
left = join_root
right = other.join_root
if left.match? right
merge_node left, right
else
# If the roots aren't the same, then deep copy the RHS to the LHS
left.children.concat right.children.map { |node|
deep_copy left, node
}
end
end
def join_constraints
make_joins join_root
end
def columns
join_root.collect { |join_part|
table = join_part.aliased_table
join_part.column_names_with_alias.collect{ |column_name, aliased_name|
table[column_name].as Arel.sql(aliased_name)
}
}.flatten
end
def instantiate(result_set)
primary_key = join_root.aliased_primary_key
parents = {}
type_caster = result_set.column_type primary_key
records = result_set.map { |row_hash|
primary_id = type_caster.type_cast row_hash[primary_key]
parent = parents[primary_id] ||= join_root.instantiate(row_hash)
construct(parent, join_root, row_hash, result_set)
parent
}.uniq
remove_duplicate_results!(base_klass, records, join_root.children)
records
end
private
def make_joins(node)
node.children.flat_map { |child|
child.join_constraints(node).concat make_joins(child)
}
end
def construct_tables!(parent, node)
node.tables = node.reflection.chain.map { |reflection|
alias_tracker.aliased_table_for(
reflection.table_name,
table_alias_for(reflection, parent, reflection != node.reflection)
)
}.reverse
end
def table_alias_for(reflection, parent, join)
name = "#{reflection.plural_name}_#{parent.table_name}"
name << "_join" if join
name
end
def merge_node(left, right)
intersection, missing = right.children.map { |node1|
[left.children.find { |node2| node1.match? node2 }, node1]
}.partition(&:first)
intersection.each { |l,r| merge_node l, r }
left.children.concat missing.map { |_,node| deep_copy left, node }
end
def deep_copy(parent, node)
dup = build_join_association(node.reflection, parent, Arel::OuterJoin)
dup.children.concat node.children.map { |n| deep_copy dup, n }
dup
end
def remove_duplicate_results!(base, records, associations)
associations.each do |node|
reflection = node.reflection
remove_uniq_by_reflection(reflection, records)
parent_records = []
records.each do |record|
if descendant = record.send(reflection.name)
if reflection.collection?
parent_records.concat descendant.target.uniq
else
parent_records << descendant
end
end
end
unless parent_records.empty?
remove_duplicate_results!(reflection.klass, parent_records, node.children)
end
end
end
def find_reflection(klass, name)
klass.reflect_on_association(name) or
raise ConfigurationError, "Association named '#{ name }' was not found on #{ klass.name }; perhaps you misspelled it?"
end
def build(associations, parent, join_type)
associations.each do |name, right|
reflection = find_reflection parent.base_klass, name
join_association = build_join_association reflection, parent, join_type
parent.children << join_association
build right, join_association, join_type
end
end
def build_scalar(reflection, parent, join_type)
join_association = build_join_association(reflection, parent, join_type)
parent.children << join_association
end
def remove_uniq_by_reflection(reflection, records)
if reflection.collection?
records.each { |record| record.send(reflection.name).target.uniq! }
end
end
def build_join_association(reflection, parent, join_type)
reflection.check_validity!
if reflection.options[:polymorphic]
raise EagerLoadPolymorphicError.new(reflection)
end
node = JoinAssociation.new(reflection, join_root.to_a.length, join_type)
construct_tables!(parent, node)
node
end
def construct(ar_parent, parent, row, rs)
primary_key = parent.aliased_primary_key
type_caster = rs.column_type primary_key
parent.children.each do |node|
primary_id = type_caster.type_cast row[primary_key]
if ar_parent.id == primary_id
model = construct_model(ar_parent, node, row)
construct(model, node, row, rs) if model
end
end
end
def construct_model(record, join_part, row)
if join_part.reflection.collection?
model = join_part.instantiate(row) unless row[join_part.aliased_primary_key].nil?
other = record.association(join_part.reflection.name)
other.loaded!
other.target.push(model) if model
other.set_inverse_instance(model)
else
return record.association(join_part.reflection.name).target if record.association_cache.key?(join_part.reflection.name)
model = join_part.instantiate(row) unless row[join_part.aliased_primary_key].nil?
set_target_and_inverse(join_part, model, record)
end
model
end
def set_target_and_inverse(join_part, model, record)
other = record.association(join_part.reflection.name)
other.target = model
other.set_inverse_instance(model)
end
end
end
end
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