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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 :join_parts, :alias_tracker, :base_klass
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
@table_joins = joins
@join_parts = [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_parts.last, Arel::InnerJoin
end
def graft(*associations)
join_assocs = join_associations
base = join_base
associations.reject { |association|
join_assocs.detect { |a| association == a }
}.each { |association|
join_part = find_parent_part(association.parent) || base
type = association.join_type
find_or_build_scalar association.reflection, join_part, type
}
self
end
def join_associations
join_parts.drop 1
end
def reflections
join_associations.map(&:reflection)
end
def join_relation(relation)
join_associations.inject(relation) do |rel,association|
association.join_relation(rel)
end
end
def columns
join_parts.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_base.aliased_primary_key
parents = {}
type_caster = result_set.column_type primary_key
assoc = associations
records = result_set.map { |row_hash|
primary_id = type_caster.type_cast row_hash[primary_key]
parent = parents[primary_id] ||= join_base.instantiate(row_hash)
construct(parent, assoc, join_associations, row_hash, result_set)
parent
}.uniq
remove_duplicate_results!(base_klass, records, assoc)
records
end
private
def associations
join_associations.each_with_object({}) do |assoc, tree|
cache_joined_association assoc, tree
end
end
def find_parent_part(parent)
join_parts.detect do |join_part|
case parent
when JoinBase
parent.base_klass == join_part.base_klass
else
parent == join_part
end
end
end
def join_base
join_parts.first
end
def remove_duplicate_results!(base, records, associations)
associations.each_key do |name|
reflection = base.reflect_on_association(name)
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, associations[name])
end
end
end
def cache_joined_association(association, tree)
associations = []
parent = association.parent
while parent != join_base
associations.unshift(parent.reflection.name)
parent = parent.parent
end
ref = associations.inject(tree) do |cache,key|
cache[key]
end
ref[association.reflection.name] ||= {}
end
def find_reflection(klass, name)
klass.reflect_on_association(name.intern) 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
@join_parts << join_association
build right, join_association, join_type
end
end
def find_or_build_scalar(reflection, parent, join_type)
unless join_association = find_join_association(reflection, parent)
join_association = build_join_association(reflection, parent, join_type)
@join_parts << join_association
end
join_association
end
def find_join_association(reflection, parent)
join_associations.detect { |j|
j.reflection == reflection && j.parent == parent
}
end
def remove_uniq_by_reflection(reflection, records)
if reflection && 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
JoinAssociation.new(reflection, join_parts.length, parent, join_type, alias_tracker)
end
def construct(parent, associations, join_parts, row, rs)
associations.sort_by { |k,_| k.to_s }.each do |association_name, assoc|
association = construct_scalar(parent, association_name, join_parts, row, rs)
construct(association, assoc, join_parts, row, rs) if association
end
end
def construct_scalar(parent, associations, join_parts, row, rs)
name = associations.to_s
join_part = join_parts.detect { |j|
j.reflection.name.to_s == name &&
j.parent_table_name == parent.class.table_name
}
raise(ConfigurationError, "No such association") unless join_part
join_parts.delete(join_part)
construct_association(parent, join_part, row, rs)
end
def construct_association(record, join_part, row, rs)
caster = rs.column_type(join_part.parent.aliased_primary_key)
row_id = caster.type_cast row[join_part.parent.aliased_primary_key]
return if record.id != row_id
macro = join_part.reflection.macro
if macro == :has_one
return record.association(join_part.reflection.name).target if record.association_cache.key?(join_part.reflection.name)
association = join_part.instantiate(row) unless row[join_part.aliased_primary_key].nil?
set_target_and_inverse(join_part, association, record)
else
association = join_part.instantiate(row) unless row[join_part.aliased_primary_key].nil?
case macro
when :has_many
other = record.association(join_part.reflection.name)
other.loaded!
other.target.push(association) if association
other.set_inverse_instance(association)
when :belongs_to
set_target_and_inverse(join_part, association, record)
else
raise ConfigurationError, "unknown macro: #{join_part.reflection.macro}"
end
end
association
end
def set_target_and_inverse(join_part, association, record)
other = record.association(join_part.reflection.name)
other.target = association
other.set_inverse_instance(association)
end
end
end
end
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