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module ActiveRecord
module Associations
class AssociationScope #:nodoc:
INSTANCE = new
def self.scope(association, connection)
INSTANCE.scope association, connection
end
def scope(association, connection)
klass = association.klass
reflection = association.reflection
scope = klass.unscoped
owner = association.owner
alias_tracker = AliasTracker.empty connection
scope.extending! Array(reflection.options[:extend])
add_constraints(scope, owner, klass, reflection, alias_tracker)
end
def join_type
Arel::Nodes::InnerJoin
end
private
def construct_tables(chain, klass, refl, alias_tracker)
chain.map do |reflection|
alias_tracker.aliased_table_for(
table_name_for(reflection, klass, refl),
table_alias_for(reflection, refl, reflection != refl)
)
end
end
def table_alias_for(reflection, refl, join = false)
name = "#{reflection.plural_name}_#{alias_suffix(refl)}"
name << "_join" if join
name
end
def join(table, constraint)
table.create_join(table, table.create_on(constraint), join_type)
end
def column_for(table_name, column_name, alias_tracker)
columns = alias_tracker.connection.schema_cache.columns_hash(table_name)
columns[column_name]
end
def bind_value(scope, column, value, alias_tracker)
substitute = alias_tracker.connection.substitute_at(
column, scope.bind_values.length)
scope.bind_values += [[column, value]]
substitute
end
def bind(scope, table_name, column_name, value, tracker)
column = column_for table_name, column_name, tracker
bind_value scope, column, value, tracker
end
def add_constraints(scope, owner, assoc_klass, refl, tracker)
chain = refl.chain
scope_chain = refl.scope_chain
tables = construct_tables(chain, assoc_klass, refl, tracker)
chain.each_with_index do |reflection, i|
table, foreign_table = tables.shift, tables.first
if reflection.source_macro == :belongs_to
if reflection.options[:polymorphic]
key = reflection.association_primary_key(assoc_klass)
else
key = reflection.association_primary_key
end
foreign_key = reflection.foreign_key
else
key = reflection.foreign_key
foreign_key = reflection.active_record_primary_key
end
if reflection == chain.last
bind_val = bind scope, table.table_name, key.to_s, owner[foreign_key], tracker
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.to_s, value, tracker
scope = scope.where(table[reflection.type].eq(bind_val))
end
else
constraint = table[key].eq(foreign_table[foreign_key])
if reflection.type
value = chain[i + 1].klass.base_class.name
bind_val = bind scope, table.table_name, reflection.type.to_s, value, tracker
scope = scope.where(table[reflection.type].eq(bind_val))
end
scope = scope.joins(join(foreign_table, constraint))
end
is_first_chain = i == 0
klass = is_first_chain ? assoc_klass : reflection.klass
# Exclude the scope of the association itself, because that
# was already merged in the #scope method.
scope_chain[i].each do |scope_chain_item|
item = eval_scope(klass, scope_chain_item, owner)
if scope_chain_item == refl.scope
scope.merge! item.except(:where, :includes, :bind)
end
if is_first_chain
scope.includes! item.includes_values
end
scope.where_values += item.where_values
scope.order_values |= item.order_values
end
end
scope
end
def alias_suffix(refl)
refl.name
end
def table_name_for(reflection, klass, refl)
if reflection == refl
# If this is a polymorphic belongs_to, we want to get the klass from the
# association because it depends on the polymorphic_type attribute of
# the owner
klass.table_name
else
reflection.table_name
end
end
def eval_scope(klass, scope, owner)
klass.unscoped.instance_exec(owner, &scope)
end
end
end
end
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