Code to reproduce the error in datajoint version 0.13.3
import datajoint as dj
schema = dj.Schema('test')
@schema
class A(dj.Lookup):
definition = """
a : int
---
q : int
"""
contents = ((1, 1), (2, 3), (3, 2))
@schema
class B(dj.Lookup):
definition = """
b : int
---
q : int
"""
contents = ((1, 1), (2, 3), (3, 2))
@schema
class C(dj.Computed):
definition = """
-> A
-> B
"""
def make(self, key):
print(key)
C.populate()Error message:
~/dev/datajoint-python/datajoint/condition.py in assert_join_compatibility(expr1, expr2)
63 if not isinstance(expr1, U) and not isinstance(expr2, U): # dj.U is always compatible
64 try:
---> 65 raise DataJointError(
66 "Cannot join query expressions on dependent attribute `%s`" % next(
67 r for r in set(expr1.heading.secondary_attributes).intersection(
DataJointError: Cannot join query expressions on dependent attribute `q`
Solution
This is indeed a bug. The default key_source should have projected out the secondary attributes. Fixing..
Workaround
As a temporary solution, you need to override the key_source to project out the shared secondary attribute from one of the parent tables:
@schema
class C(dj.Computed):
definition = """
-> A
-> B
"""
@property
def key_source(self):
return A.proj() * B
def make(self, key):
print(key)
Code to reproduce the error in datajoint version 0.13.3
Error message:
Solution
This is indeed a bug. The default
key_sourceshould have projected out the secondary attributes. Fixing..Workaround
As a temporary solution, you need to override the
key_sourceto project out the shared secondary attribute from one of the parent tables: