On Tuesday 19 December 2006 23:22, David Turner wrote:
> from sqlobject import *
> from sqlobject.inheritance import InheritableSQLObject
>
> __connection__ = "sqlite:/:memory:?debug=t"
>
> class Versionable(InheritableSQLObject):
> version = StringCol()
>
> class Task(Versionable):
> name = StringCol()
> task_list = ForeignKey("TaskList")
>
> class TaskList(Versionable):
> name = StringCol()
> tasks = MultipleJoin("Task")
> category = ForeignKey("Category")
>
> class Category(SQLObject):
> tag = StringCol()
> tasklists = MultipleJoin("TaskList")
>
> #class Version(SQLObject):
> # versions = MultipleJoin("Versionable")
>
>
> Versionable.createTable()
> Task.createTable()
> TaskList.createTable()
> Category.createTable()
> #Version.createTable()
>
> cat = Category(tag="important")
> tl = TaskList(name="tasks", version = 1, category = cat)
> task1 = Task(name="take out trash", task_list = tl, version = 1)
> task2 = Task(name="bathe cat", task_list = tl, version = 1)
> task3 = Task(name="bandage wounds", task_list = tl, version = 1)
>
> assert len(list(Task.select(AND(LIKE(Task.q.name, '%e%'),
> Task.q.task_listID == tl.id, TaskList.q.categoryID == cat.id)))) == 3
>
>
> ------------------
> Here's the query:
> 25/QueryR : SELECT versionable.id, versionable.version,
> versionable.child_name FROM versionable, task, task_list WHERE
> (((((task.name LIKE ('%e%')) AND (((task.task_list_id) = (1)) AND
> ((task_list.category_id) = (1)))) AND ((versionable.child_name) =
> ('Task'))) AND ((task.id) = (versionable.id))) AND ((task_list.id) =
> (versionable.id)))
>
>
> Of course it is wrong, because both tables are joined to versionable at
> once, so there will never be any results.
I don't consider this a bug in the strict sense of the word - you are abusing
InheritableSQLObject. By inheriting from it, you make things essentially the
same kind, but all you really want is them all to respond to a common
interface.
You should instead go for "common" inheritance, as it is shown in e.g.
test_inheritance.py from sqlobject's tests:
class Super(SQLObject):
name = StringCol(length=10)
class Sub(Super):
name2 = StringCol(length=10)
def test_super():
setupClass(Super)
setupClass(Sub)
s1 = Super(name='one')
s2 = Super(name='two')
s3 = Super.get(s1.id)
assert s1 == s3
def test_sub():
setupClass(Super)
setupClass(Sub)
s1 = Sub(name='one', name2='1')
s2 = Sub(name='two', name2='2')
s3 = Sub.get(s1.id)
assert s1 == s3
Diez
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