How to store and search list in SQLAlchemy?

If you add backref onto your ItemAttribute relationship:

item_id = Column(Integer, ForeignKey('items.id', onupdate='CASCADE', ondelete='CASCADE'))
item = relationship(Items, backref='attributes')

This will create and Item.attributes[] array which contains the ItemAttribute's. You might also add the onupdate and ondelete if you're using mysql.

Then when you query, you can do this:

rs = mySession.query(Items)
firstItem = rs.first()
for attribute in firstItem.attributes:
   print attribute

When querying you can filter by joining the backref:

rs = mySession.query(Items).join(Items.attributes).filter(ItemAttribute.name=='somethingSpecial')

Further, if it's a one to one relationship (but it's not in this case), you could skip the list by specifing uselist=False:

item = relationship(ITEM, backref='attribute', uselist=False)