Hi,
I'm building a search application on top of a database with historical
information. The data model is not very complex, I think, but I found
myself running into the following problem:
Say I have SQLObject class Foo like so:
class Foo(SQLObject):
_connection = hub
class sqlmeta:
defaultOrder = 'startdate'
startdate = DateCol()
bar = ForeignKey('Bar')
And a Bar class, that has a relation to Foo, like so:
class Bar(SQLObject):
_connection = hub
class sqlmeta:
defaultOrder = 'name'
name = UnicodeCol()
foos = MultipleJoin('Foo')
And then I create some data:
b1 = Bar(name='bar one')
f1 = Foo(startdate=None, bar=b1)
f3 = Foo(startdate=date(2006,1,12), bar=b1)
I can can now do:
for foo in b1.foos:
print foo.startdate
However, in this case, since some of the records in the Foo table have a
NULL value for the startdate and since the Foo class has a default order
for startdate specified, a TypeError exception is raised (the last couple
of lines of the traceback are pasted at the end of this message).
Apparently (by looking a the traceback), the sorting on the startdate
attribute is done in SQLObject, on a Python level. There it tries to
compare a datetime value for the startdate field of one record to a None
value of another, which breaks (for string or integers this would have
worked).
I think this is an issue in SQLObject that could be solved (see below for a
possible patch), but it could very well be I do something wrong here...
Maybe I should handle this type of relation differently?
kind regards,
jw
--
Jan-Wijbrand Kolman
jw...@in...
tb:
File
"/usr/lib/python2.4/site-packages/SQLObject-0.7.0-py2.4.egg/sqlobject/joins.py",
line 136, in performJoin
return self._applyOrderBy([self.otherClass.get(id, conn) for (id,)
in ids if id is not None], self.otherClass)
File
"/usr/lib/python2.4/site-packages/SQLObject-0.7.0-py2.4.egg/sqlobject/joins.py",
line 81, in _applyOrderBy
results.sort(sorter(self.orderBy))
File
"/usr/lib/python2.4/site-packages/SQLObject-0.7.0-py2.4.egg/sqlobject/joins.py",
line 104, in cmper
return cmp(getattr(a, attr), getattr(b, attr))
TypeError: can't compare datetime.date to NoneType
possible patch:
--- src/SQLObject-0.7.0-orig/sqlobject/joins.py 2005-10-02
00:59:35.000000000 +0200
+++ src/SQLObject-0.7.0/sqlobject/joins.py 2006-01-12
22:00:15.000000000 +0100
@@ -97,11 +97,21 @@
# @@: but we don't handle more complex expressions for orderings
if orderBy.startswith('-'):
orderBy = orderBy[1:]
- def cmper(a, b, attr=orderBy):
- return cmp(getattr(b, attr), getattr(a, attr))
+ reverse = True
else:
- def cmper(a, b, attr=orderBy):
- return cmp(getattr(a, attr), getattr(b, attr))
+ reverse = False
+
+ def cmper(a, b, attr=orderBy, rev=reverse):
+ a, b = getattr(a, attr), getattr(b, attr)
+ if rev:
+ a, b = b, a
+ if a is None:
+ if b is None:
+ return 0
+ return -1
+ if b is None:
+ return 1
+ return cmp(a, b)
return cmper
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