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module ActiveRecord
module Associations
class AssociationScope #:nodoc:
def self.scope(association, connection)
INSTANCE.scope association, connection
end
class BindSubstitution
def initialize(block)
@block = block
end
def bind_value(scope, column, value, connection)
substitute = connection.substitute_at(column)
scope.bind_values += [[column, @block.call(value)]]
substitute
end
end
def self.create(&block)
block = block ? block : lambda { |val| val }
new BindSubstitution.new(block)
end
def initialize(bind_substitution)
@bind_substitution = bind_substitution
end
INSTANCE = create
def scope(association, connection)
klass = association.klass
reflection = association.reflection
scope = klass.unscoped
owner = association.owner
alias_tracker = AliasTracker.empty connection
chain = get_chain(reflection, association)
scope.extending! Array(reflection.options[:extend])
add_constraints(scope, owner, klass, reflection, alias_tracker, chain)
end
def join_type
Arel::Nodes::InnerJoin
end
def self.get_bind_values(owner, chain)
binds = []
last_reflection = chain.last
binds << last_reflection.join_id_for(owner)
if last_reflection.type
binds << owner.class.base_class.name
end
chain.each_cons(2).each do |reflection, next_reflection|
if reflection.type
binds << next_reflection.klass.base_class.name
end
end
binds
end
private
def construct_tables(chain, alias_tracker, name)
chain.map do |reflection|
reflection.alias_name(name, alias_tracker)
end
end
def join(table, constraint)
table.create_join(table, table.create_on(constraint), join_type)
end
def column_for(table_name, column_name, connection)
columns = connection.schema_cache.columns_hash(table_name)
columns[column_name]
end
def bind_value(scope, column, value, connection)
@bind_substitution.bind_value scope, column, value, connection
end
def bind(scope, table_name, column_name, value, connection)
column = column_for table_name, column_name, connection
bind_value scope, column, value, connection
end
def last_chain_scope(scope, table, reflection, owner, connection, assoc_klass)
join_keys = reflection.join_keys(assoc_klass)
key = join_keys.key
foreign_key = join_keys.foreign_key
bind_val = bind scope, table.table_name, key.to_s, owner[foreign_key], connection
scope = scope.where(table[key].eq(bind_val))
if reflection.type
value = owner.class.base_class.name
bind_val = bind scope, table.table_name, reflection.type, value, connection
scope = scope.where(table[reflection.type].eq(bind_val))
else
scope
end
end
def next_chain_scope(scope, table, reflection, connection, assoc_klass, foreign_table, next_reflection)
join_keys = reflection.join_keys(assoc_klass)
key = join_keys.key
foreign_key = join_keys.foreign_key
constraint = table[key].eq(foreign_table[foreign_key])
if reflection.type
value = next_reflection.klass.base_class.name
bind_val = bind scope, table.table_name, reflection.type, value, connection
scope = scope.where(table[reflection.type].eq(bind_val))
end
scope = scope.joins(join(foreign_table, constraint))
end
class RuntimeReflection
def initialize(reflection, association)
@reflection = reflection
@association = association
end
def klass
@association.klass
end
def scope
@reflection.scope
end
def table_name
klass.table_name
end
def plural_name
@reflection.plural_name
end
def join_keys(assoc_klass)
@reflection.join_keys(assoc_klass)
end
def type
@reflection.type
end
def constraints
@reflection.constraints
end
def source_type_info
@reflection.source_type_info
end
def alias_name(name, alias_tracker)
@alias ||= begin
alias_name = "#{plural_name}_#{name}_join"
table_name = klass.table_name
alias_tracker.aliased_table_for(table_name, alias_name)
end
end
end
class ReflectionProxy < SimpleDelegator
def alias_name(name, alias_tracker)
@alias ||= begin
alias_name = "#{plural_name}_#{name}"
alias_tracker.aliased_table_for(table_name, alias_name)
end
end
end
def get_chain(reflection, association)
chain = reflection.chain.map { |reflection|
ReflectionProxy.new(reflection)
}
chain[0] = RuntimeReflection.new(reflection, association)
chain
end
def add_constraints(scope, owner, assoc_klass, refl, tracker, chain)
construct_tables(chain, tracker, refl.name)
owner_reflection = chain.last
table = owner_reflection.alias_name(refl.name, tracker)
scope = last_chain_scope(scope, table, owner_reflection, owner, tracker, assoc_klass)
# chain.first always == refl
chain.each_with_index do |reflection, i|
table = reflection.alias_name(refl.name, tracker)
unless reflection == chain.last
next_reflection = chain[i + 1]
foreign_table = next_reflection.alias_name(refl.name, tracker)
scope = next_chain_scope(scope, table, reflection, tracker, assoc_klass, foreign_table, next_reflection)
end
# Exclude the scope of the association itself, because that
# was already merged in the #scope method.
reflection.constraints.each do |scope_chain_item|
item = eval_scope(reflection.klass, scope_chain_item, owner)
if scope_chain_item == refl.scope
scope.merge! item.except(:where, :includes, :bind)
end
if i == 0
scope.includes! item.includes_values
end
scope.where_values += item.where_values
scope.bind_values += item.bind_values
scope.order_values |= item.order_values
end
end
scope
end
def eval_scope(klass, scope, owner)
klass.unscoped.instance_exec(owner, &scope)
end
end
end
end
|
