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
28725	In multi-table inheritance, serializers output ManyToManyFields in both the parent and the base class which causes an error with loaddata	宅教授	Nadege	"models:
{{{
class Root(Model):
    varchar_field_a
    many_to_many_field

class Sub(Root):
    varchar_field_b
}}}

cmd: `python manager.py dumpdata`, output:
{{{
[
  {
    ""pk"": 1, 
    ""model"": ""label.sub"", 
    ""fields"": {
      ""varchar_field_b"": ""b"",
      ""many_to_many_field"": [...]
    }
  },
  ...
]
}}}

The point is, its export the many-to-many field in the parent class.
cmd: `python manager.py loaddata`, import the above data. Triggered by repeated import many-to-many data uniqueness constraints."	Bug	closed	Core (Serialization)	dev	Normal	fixed			Ready for checkin	1	0	0	0	0	0