class Companies(models.Model)
    user = models.ForeignKey(User)
    company_name = models.CharField(max_length=200)
    dealing = models.ForeignKey(Dealings)
    
class Dealings(models.Model)
    dealing_number = models.CharField(max_length=200)
    dealing_item = models.ForeignKey(DealingsItem)
    
class DealingsItem(models.Model)
    propfield = models.CharField(max_length=200)

"""
The problem is that the request should go on Dealing
Dealing.objects.select_related().filter(dealing_number__startswith=201)
But still I need to do filter by company name
"""