[Sqlalchemy-tickets] Issue #3826: Session commit changes the order of a relationship elements (zzzeek/sqlalchemy)

[metalstorm <iss...@bi...>]

New issue 3826: Session commit changes the order of a relationship elements
https://bitbucket.org/zzzeek/sqlalchemy/issues/3826/session-commit-changes-the-order-of-a

metalstorm:



If you have a model that contains a basic relationship like so:


```
#!python

from sqlalchemy import Column, Integer, String, Boolean, ForeignKey, Table, DateTime
from sqlalchemy.ext.declarative import declarative_base

Base = declarative_base()

class Thing(Base)

    parts = relationship('Part', backref='thing')

class Part(Base):

    name = Column(String, primary_key=True, default='')

```

And then you do:


```
#!python

thing = Thing()

part1 = Part(name="Part1")
part2 = Part(name="Part2") 

# Note we do part2 then part1
thing.parts.append(part2)
thing.parts.append(part1)

print thing.parts
# [Part2, Part1]

session.commit()

print thing.parts
# [Part1, Part2]
```

It seems like the session orders the result based on primary key (by default), which I guess is expected. But if the session already contains the instances, then should it change the order?