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# frozen_string_literal: true
module ActiveRecord
module Associations
class JoinDependency # :nodoc:
extend ActiveSupport::Autoload
eager_autoload do
autoload :JoinBase
autoload :JoinAssociation
end
class Aliases # :nodoc:
def initialize(tables)
@tables = tables
@alias_cache = tables.each_with_object({}) { |table, h|
h[table.node] = table.columns.each_with_object({}) { |column, i|
i[column.name] = column.alias
}
}
@columns_cache = tables.each_with_object({}) { |table, h|
h[table.node] = table.columns
}
end
def columns
@tables.flat_map(&:column_aliases)
end
def column_aliases(node)
@columns_cache[node]
end
def column_alias(node, column)
@alias_cache[node][column]
end
Table = Struct.new(:node, :columns) do # :nodoc:
def column_aliases
t = node.table
columns.map { |column| t[column.name].as(column.alias) }
end
end
Column = Struct.new(:name, :alias)
end
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
def initialize(base, table, associations, join_type)
tree = self.class.make_tree associations
@join_root = JoinBase.new(base, table, build(tree, base))
@join_type = join_type
end
def base_klass
join_root.base_klass
end
def reflections
join_root.drop(1).map!(&:reflection)
end
def join_constraints(joins_to_add, alias_tracker, references)
@alias_tracker = alias_tracker
@joined_tables = {}
@references = {}
references.each do |table_name|
@references[table_name.to_sym] = table_name if table_name.is_a?(Arel::Nodes::SqlLiteral)
end unless references.empty?
joins = make_join_constraints(join_root, join_type)
joins.concat joins_to_add.flat_map { |oj|
if join_root.match? oj.join_root
walk(join_root, oj.join_root, oj.join_type)
else
make_join_constraints(oj.join_root, oj.join_type)
end
}
end
def instantiate(result_set, strict_loading_value, &block)
primary_key = aliases.column_alias(join_root, join_root.primary_key)
seen = Hash.new { |i, parent|
i[parent] = Hash.new { |j, child_class|
j[child_class] = {}
}
}.compare_by_identity
model_cache = Hash.new { |h, klass| h[klass] = {} }
parents = model_cache[join_root]
column_aliases = aliases.column_aliases(join_root)
column_names = []
result_set.columns.each do |name|
column_names << name unless /\At\d+_r\d+\z/.match?(name)
end
if column_names.empty?
column_types = {}
else
column_types = result_set.column_types
unless column_types.empty?
attribute_types = join_root.attribute_types
column_types = column_types.slice(*column_names).delete_if { |k, _| attribute_types.key?(k) }
end
column_aliases += column_names.map! { |name| Aliases::Column.new(name, name) }
end
message_bus = ActiveSupport::Notifications.instrumenter
payload = {
record_count: result_set.length,
class_name: join_root.base_klass.name
}
message_bus.instrument("instantiation.active_record", payload) do
result_set.each { |row_hash|
parent_key = primary_key ? row_hash[primary_key] : row_hash
parent = parents[parent_key] ||= join_root.instantiate(row_hash, column_aliases, column_types, &block)
construct(parent, join_root, row_hash, seen, model_cache, strict_loading_value)
}
end
parents.values
end
def apply_column_aliases(relation)
@join_root_alias = relation.select_values.empty?
relation._select!(-> { aliases.columns })
end
def each(&block)
join_root.each(&block)
end
protected
attr_reader :join_root, :join_type
private
attr_reader :alias_tracker, :join_root_alias
def aliases
@aliases ||= Aliases.new join_root.each_with_index.map { |join_part, i|
column_names = if join_part == join_root && !join_root_alias
primary_key = join_root.primary_key
primary_key ? [primary_key] : []
else
join_part.column_names
end
columns = column_names.each_with_index.map { |column_name, j|
Aliases::Column.new column_name, "t#{i}_r#{j}"
}
Aliases::Table.new(join_part, columns)
}
end
def make_join_constraints(join_root, join_type)
join_root.children.flat_map do |child|
make_constraints(join_root, child, join_type)
end
end
def make_constraints(parent, child, join_type)
foreign_table = parent.table
foreign_klass = parent.base_klass
child.join_constraints(foreign_table, foreign_klass, join_type, alias_tracker) do |reflection|
table, terminated = @joined_tables[reflection]
root = reflection == child.reflection
if table && (!root || !terminated)
@joined_tables[reflection] = [table, root] if root
next table, true
end
table_name = @references[reflection.name.to_sym]&.to_s
table = alias_tracker.aliased_table_for(reflection.klass.arel_table, table_name) do
name = reflection.alias_candidate(parent.table_name)
root ? name : "#{name}_join"
end
@joined_tables[reflection] ||= [table, root] if join_type == Arel::Nodes::OuterJoin
table
end.concat child.children.flat_map { |c| make_constraints(child, c, join_type) }
end
def walk(left, right, join_type)
intersection, missing = right.children.map { |node1|
[left.children.find { |node2| node1.match? node2 }, node1]
}.partition(&:first)
joins = intersection.flat_map { |l, r| r.table = l.table; walk(l, r, join_type) }
joins.concat missing.flat_map { |_, n| make_constraints(left, n, join_type) }
end
def find_reflection(klass, name)
klass._reflect_on_association(name) ||
raise(ConfigurationError, "Can't join '#{klass.name}' to association named '#{name}'; perhaps you misspelled it?")
end
def build(associations, base_klass)
associations.map do |name, right|
reflection = find_reflection base_klass, name
reflection.check_validity!
reflection.check_eager_loadable!
if reflection.polymorphic?
raise EagerLoadPolymorphicError.new(reflection)
end
JoinAssociation.new(reflection, build(right, reflection.klass))
end
end
def construct(ar_parent, parent, row, seen, model_cache, strict_loading_value)
return if ar_parent.nil?
parent.children.each do |node|
if node.reflection.collection?
other = ar_parent.association(node.reflection.name)
other.loaded!
elsif ar_parent.association_cached?(node.reflection.name)
model = ar_parent.association(node.reflection.name).target
construct(model, node, row, seen, model_cache, strict_loading_value)
next
end
if node.primary_key
key = aliases.column_alias(node, node.primary_key)
id = row[key]
else
key = aliases.column_alias(node, node.reflection.join_primary_key.to_s)
id = nil # Avoid id-based model caching.
end
if row[key].nil?
nil_association = ar_parent.association(node.reflection.name)
nil_association.loaded!
next
end
unless model = seen[ar_parent][node][id]
model = construct_model(ar_parent, node, row, model_cache, id, strict_loading_value)
seen[ar_parent][node][id] = model if id
end
construct(model, node, row, seen, model_cache, strict_loading_value)
end
end
def construct_model(record, node, row, model_cache, id, strict_loading_value)
other = record.association(node.reflection.name)
unless model = model_cache[node][id]
model = node.instantiate(row, aliases.column_aliases(node)) do |m|
m.strict_loading! if strict_loading_value
other.set_inverse_instance(m)
end
model_cache[node][id] = model if id
end
if node.reflection.collection?
other.target.push(model)
else
other.target = model
end
model.readonly! if node.readonly?
model.strict_loading! if node.strict_loading?
model
end
end
end
end