Order of join clause with alias join and select can lead to invalid configurations

[jakedt]

I'm not sure how to describe the problem accurately, so here is a repro case:

from peewee import Model, SqliteDatabase, CharField, ForeignKeyField, create_model_tables

db = SqliteDatabase(':memory:')

class Person(Model):
    name = CharField(default='aperson')
    class Meta:
        database = db

class RelatesToPerson(Model):
    name = CharField(default='arelationship')
    person = ForeignKeyField(Person)
    class Meta:
        database = db

create_model_tables([Person, RelatesToPerson])

PersonAlias = Person.alias()

a_person = Person.create()
RelatesToPerson.create(person=a_person)

print str(RelatesToPerson
          .select(RelatesToPerson, PersonAlias)
          .join(PersonAlias, on=(PersonAlias.id == RelatesToPerson.person))
          .get().id) + " <- an instance!"

print (RelatesToPerson
       .select(RelatesToPerson, PersonAlias)
       .join(PersonAlias, on=(RelatesToPerson.person == PersonAlias.id))
       .get().id)

output

$ python repro.py
<__main__.Person object at 0x10b201c50> <- an instance!
1

[coleifer]

Thanks for sharing some code to reproduce this!

[coleifer]

Basically what peewee is trying to figure out is how to patch the joined instance (PersonAlias, which is actually a Person) onto RelatesToPerson given the join predicate. There's some special-casing around aliases and expressions -- I think there are some undiscovered bugs in the relevant block of code. I'm working on a complete refactor to hopefully clean this up and make the behavior more predictable.

[coleifer]

I've got things partially fixed in 5537389

[coleifer]

I believe this is now fixed.