django - OneToOneField QuerySet returning empty dict -

i have 2 models called manufacturer , car . car model has foreignkey manufacturer mean many cars can belong single manufacturer. in model manfacturer , onetoonefield called showcase allows manufacturer have single car showcase, how can show manufacturers have car showcase mean , show manufacturer onetoonefield objects.

i tried manufacturer.objects.filter(showcase=true) return empty dictionary []

class manufacturer(models.model):       user = models.foreignkey(user)     name = models.charfield(max_length=55)     showcase = models.onetoonefield('car',related_name='car',blank=true)    class car(models.model):     user = models.foreignkey(user)     manufacturer = models.foreignkey(manufacturer,blank=false,related_name='manufacturer') 

try manufacturer.objects.exclude(showcase=none)

also, in model try add null=true next to blank=true in showcase attribute of model.