I have implemented a very basic Q object. Under controlled conditions,
it works great. Here it is:
class QCompare(models.Q):
""" QCompare object allows you to compare two fields of one or two
models
Example: queryset.filter(QCompare('>', Model1, 'field1', Model2,
'field2'))
"""
def __init__(self, op, model1, field1, model2, field2):
""" Init the Q object """
if isinstance(model1, models.base.ModelBase):
if field1 is None or field1 == 'pk':
field1 = model1._meta.pk.name
try:
field1 = model1._meta.get_field(field1).column
except AttributeError, e:
raise AttributeError, "%s: %s" % (e, "model: %s,
field: %s" % model1, field1)
model1 = model1._meta.db_table
if isinstance(model2, models.base.ModelBase):
if field2 is None or field2 == 'pk':
field2 = model2._meta.pk.name
try:
field2 = model2._meta.get_field(field2).column
except AttributeError, e:
raise AttributeError, "%s: %s" % (e, "model: %s,
field: %s" % model1, field1)
model2 = model2._meta.db_table
# Create the WHERE clause
self.where = "%s.%s %s %s.%s" % (model1, field1, op, model2,
field2)
def get_sql(self, opts):
""" Return the SQL clause """
return ({}, [self.where,], [])
--
Costin Stroie
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