Ticket #55: test_assoc.py

from elixir import *
metadata.bind='sqlite:///'

from sqlalchemy.orm.collections import attribute_mapped_collection

class Item(Entity):
        name = Field(String(128))
        attributes = OneToMany('Attribute', collection_class=attribute_mapped_collection('name'))
        
        def __repr__(self):
                return 'Item(%s)' % (self.name,)

class Attribute(Entity):
        item = ManyToOne('Item', primary_key=True)
        name = Field(String(128), primary_key=True)

        def __repr__(self):
                return 'Attribute(%s, %s)' % (self.name, self.value)
 
setup_all(True)

item1 = Item(name='item1')
# uncomment this to fail at the first assertion
#print item1.attributes 
attr1 = Attribute(name='attr1key', value='attr1value', item=item1)
print item1.attributes
assert not None in item1.attributes
assert 'attr1key' in item1.attributes
assert attr1 in session.new

# this works fine, even after accessing item1.attributes
attr2 = Attribute(name='attr2key', value='attr2value')
# because we've explicitly deferred setting the .item until
#  after the attribute is instantiated.
attr2.item = item1
print item1.attributes
assert not None in item1.attributes
assert 'attr2key' in item1.attributes
assert attr2 in session.new

# anytime after we've accessed item1.attributes, if we try to initialize
# an attribute for that item, the attribute will not be correctly
# associated and will be lost from the session.
attr3 = Attribute(name='attr3key', value='attr3value', item=item1)
print item1.attributes
assert not None in item1.attributes
assert 'attr3key' in item1.attributes
assert attr3 in session.new