[Sqlalchemy-tickets] Issue #3029: fully self equated join condition? (zzzeek/sqlalchemy)

[Mike B. <iss...@bi...>]

New issue 3029: fully self equated join condition?
https://bitbucket.org/zzzeek/sqlalchemy/issue/3029/fully-self-equated-join-condition

Mike Bayer:


```
#!python

from sqlalchemy import *
from sqlalchemy.orm import *
from sqlalchemy.ext.declarative import declarative_base

Base = declarative_base()

class Category(Base):
    __tablename__ = 'categories'

    id = Column(SmallInteger, primary_key=True)
    path = Column(String, unique=True, nullable=False)

    all_subcats = relationship('Category', viewonly=True,
                               primaryjoin=path == remote(foreign(path)).concat('%')
                               )

print Session().query(Category).options(joinedload("all_subcats"))
```

patch:

```
#!diff


diff --git a/lib/sqlalchemy/orm/relationships.py b/lib/sqlalchemy/orm/relationships.py
index 311fba4..ed0a9a5 100644
--- a/lib/sqlalchemy/orm/relationships.py
+++ b/lib/sqlalchemy/orm/relationships.py
@@ -2405,6 +2405,10 @@ class JoinCondition(object):
                     self.direction = ONETOMANY
                 elif manytoone_local and not onetomany_local:
                     self.direction = MANYTOONE
+                elif self_equated.intersection(self.foreign_key_columns):
+                    self.direction = ONETOMANY
+                elif self_equated and not self_equated.intersection(self.foreign_key_columns):
+                    self.direction = MANYTOONE
                 else:
                     raise sa_exc.ArgumentError(
                         "Can't determine relationship"
```