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
28394	BaseExpression.output_field is resolved incorrectly if source expressions have directly set output_field	Sergey Fedoseev	Sergey Fedoseev	"{{{
In [1]: from django.db import models
In [2]: from django.db.models.expressions import Func
In [3]: class FuncA(Func):
   ...:         output_field = models.CharField()
   ...:     
In [4]: class FuncB(Func):
   ...:         pass
   ...: 
In [5]: expr = FuncB(FuncA(models.IntegerField()))
In [6]: expr.output_field
---------------------------------------------------------------------------
FieldError                                Traceback (most recent call last)
<ipython-input-6-ac0033dafa8f> in <module>()
----> 1 expr.output_field

/home/sergey/dev/django/django/utils/functional.py in __get__(self, instance, cls)
     34         if instance is None:
     35             return self
---> 36         res = instance.__dict__[self.name] = self.func(instance)
     37         return res
     38 

/home/sergey/dev/django/django/db/models/expressions.py in output_field(self)
    225         """"""Return the output type of this expressions.""""""
    226         if self._output_field_or_none is None:
--> 227             raise FieldError(""Cannot resolve expression type, unknown output_field"")
    228         return self._output_field_or_none
    229 

FieldError: Cannot resolve expression type, unknown output_field
}}}"	Bug	closed	Database layer (models, ORM)	dev	Normal	fixed			Accepted	1	0	0	0	0	0