How to get table data (including child table and sub child data) based on id which obtains from another table data? Django

Question

views

company = Company.objects.get(id = company_id)  # getting input from django urls (<int:company_id>)
vehicles = CompanyContainVehicles.objects.filter(company_id=company.id)  # Give all rows having same id (company.id)
all_vehicles = Vehicle.objects.filter(companies=company)  # Gives all row with id provide by company
all_vehicles_parts = VehiclePart.objects.filter(__________) # Not Working

models

class Company(models.Model):
    name = models.CharField(max_length=255)
    slug = models.SlugField(blank=True, null=True, unique=True)
    description = models.TextField()

class Vehicle(models.Model):
    vehicle_number = models.IntegerField()
    name = models.CharField(max_length=255)
    slug = models.SlugField(blank=True, null=True, unique=True)
    companies = models.ManyToManyField(
        Company,
        through='CompanyVehicle',
        related_name='companies'
    )

class CompanyVehicle(models.Model):
    company = models.ForeignKey(Company, on_delete=models.CASCADE)
    vehicle = models.ForeignKey(Vehicle, on_delete=models.CASCADE)
    created_at = models.DateTimeField(auto_now_add=True)

class VehiclePart(models.Model):
    id = models.AutoField(primary_key=True)
    vehicle = models.ForeignKey(Vehicle, on_delete=models.CASCADE)
    type = models.ForeignKey(PartType, on_delete=models.CASCADE)
    created_at = models.DateTimeField(auto_now_add=True, blank=True)

How do I get VehiclePart's with their Vehicle? (I think I will give all the data in a variable and we should divide it and add it with their Vehicle). Also, what can we do to access data if VehiclePart contains a child class named VehiclePartDetail?

Answer 1

I think I will give all the data in a variable and we should divide it and add with their Vehicle.

You don't have to. Django can read ForeignKey relations in reverse. You can query with:

qs = Vehicle.objects.prefetch_related('vehiclepart_set')

then you can enumerate over the queryset, and for each Vehicle object, access this with .vehiclepart_set.all(). For example:

for item in qs:
    print(vehicle_name)
    for part in item.vehiclepart_set.all():
        print(part.id)