mapped_collection should honor explicit dictionary key (or at least raise an error if a mismatch is present)

the example illustrates using attribute_mapped_collection and assignment of a full dictionary. the value in the dictionary does not yet have the "key" attribute assigned, but shouldn't be needed since we are passing in the full dict (or if this is not supported should raise an error. this might be a "quick fix" for now at least if the error says 'not supported yet').

later, the mismatched dictionary creates a KeyError inside of attributes.CollectionAttributeImpl.set() when the "remove" event fires on the old dictionary. we should at least detect this condition if not fix it altogether.

from sqlalchemy import *
from sqlalchemy.orm import *
from sqlalchemy.orm.collections import attribute_mapped_collection

engine = create_engine('sqlite://')

class Base(object):
    def __init__(self, **kwargs):
        for k in kwargs:
            setattr(self, k, kwargs[k](k))

class Product(Base):
    pass

class ProductDescription(Base):
    pass

class Language(Base):
    pass

meta = MetaData(engine)

products = Table('products', meta, 
    Column('id', Integer, primary_key=True))

languages = Table('languages', meta, 
    Column('id', Integer, primary_key=True),
    Column('name', String(50))
    )

product_descriptions = Table('product_descriptions', meta, 
    Column('product_id', Integer, ForeignKey('products.id'), primary_key=True),
    Column('language_id', Integer, ForeignKey('languages.id'), primary_key=True),
    Column('description', String(255)),
    )

meta.create_all()

languages.insert().execute(id=1, name='english')

mapper(Product, products, properties={
    'descriptions':relation(ProductDescription, 
    collection_class=attribute_mapped_collection('language_id'), cascade="all, delete-orphan")
})
mapper(ProductDescription, product_descriptions, properties={
    'language':relation(Language)
})
mapper(Language, languages)


sess = create_session()
english = sess.query(Language).filter(Language.name=='english').one()

p1 = Product(descriptions={english.id:ProductDescription(language=english, description='description #1')})

# this is the source of the bug.  ProductDescription doesn't have a language_id yet, so it gets placed 
# under the key "None".  if you set language_id=english.id on ProductDescription, then it works
try:
    assert english.id in p1.descriptions
except AssertionError:
    print "assertion failed: english.id is not the key"

try:
    assert None not in p1.descriptions
except AssertionError:
    print "assertion failed: the ProductDescription is keyed underneath 'None'"

sess.save(p1)
sess.flush()

# later, when we want to change things, attributes.set() gets screwed up as well
p1.descriptions = {english.id:ProductDescription(language=english, description='description #2')}  # <-- KeyError

Comments (12)