id	summary	reporter	owner	description	type	status	component	version	severity	resolution	keywords	cc	stage	has_patch	needs_docs	needs_tests	needs_better_patch	easy	ui_ux
13774	Add model Field.rel_db_type() method	Alexander Schepanovski	Alexander Schepanovski	"rel_db_type() method will return db_type for ForeignKey / OneToOneField to a field, 
if not exists value of db_type() method should be used as it's done now.

It will remove a need for a hack in ForeignKey.db_type and make possible subclasses of AutoField work such as:

{{{
class BigAutoField(models.AutoField):
    def __init__(self, verbose_name=None, name=None, external_sequence=False, **kwargs):
        self.external_sequence = external_sequence
        models.AutoField.__init__(self, verbose_name, name, **kwargs)

    def db_type(self, connection):
        # now only for PostgreSQL, should be done more carefully to support other backends
        return 'bigint' if self.external_sequence else 'bigserial'

    def rel_db_type(self, connection):
        return 'bigint'
}}}


"	New feature	closed	Database layer (models, ORM)	1.2	Normal	fixed	db, ForeignKey, related fields	Sergey Kolosov alecs.box@…	Accepted	1	1	0	0	0	0