python - A simple database inner join using django -

i have 2 tables legacy database imported django app using inspectdb

here model definition

class appcosts(models.model):     cost = models.decimalfield(max_digits=10, decimal_places=2)   class appdefinitions(models.model):     data = models.textfield()     permissions = models.charfield(max_length=50, blank=true)     appcost=models.onetoonefield(appcosts, db_column='id') 

every app in appdefinitions has 1 entry in appcosts - 1 one relationship

when use select_related() :

>>> appdefinitions.objects.select_related().query.__str__()      u'select _app_definitions.id, _app_definitions.data,   _app_definitions.permissions, _app_definitions.id, _app_costs.id,    _app_costs.cost _app_definitions inner join _app_costs    on ( _app_definitions.id = _app_costs.id )'  >>> = appdefinitions.objects.select_related().first()  >>> a.id u'abaqus'  >>> a.cost traceback (most recent call last):   file "<console>", line 1, in <module> attributeerror: 'appdefinitions' object has no attribute 'cost'  >>> a.appcost <appcosts: abaqus,1.50>      >>> a.appcost.cost decimal('1.50') 

now there 2 problems :

• the query pulls in id twice both fields (not big deal because table wont have more few hundred entries @ most, still, want right)
• i have access cost x.appcost.cost, rather x.cost

how achieve this?

i loath use custom sql, because defeat purpose of using django's orm in first place.

you want use django's orm, want diametrically opposed that, ie accessing cost x.cost.

django not let that, since breaks object model. cost attribute on appcosts model, not costs one. if it's bothering you, could add property on costs returns self.appcosts.cost, want long don't try use in queries.