How to relationship such a connection in django? - django

Question

I need to implement a "end-to-end" connection between products.
like this:
I automatically put down two-way links between two products. But when I link product A to product B and product B to product C, there is no connection between A and C. It is necessary that they communicate themselves when putting down the two previous links.
Models.py
from django.db import models
class Part(models.Model):
brand = models.CharField('Производитель', max_length=100, blank=True)
number = models.CharField('Артикул', max_length=100, unique=True)
name = models.CharField('Название', max_length=100, blank=True)
description = models.TextField('Комментарий', blank=True, max_length=5000)
analog = models.ManyToManyField('self',blank=True, related_name='AnalogParts')
images = models.FileField('Главное изображение', upload_to = 'parts/', blank=True)
images0 = models.FileField('Дополнительное фото', upload_to = 'parts/', blank=True)
images1 = models.FileField('Дополнительное фото', upload_to = 'parts/', blank=True)
images2 = models.FileField('Дополнительное фото', upload_to = 'parts/', blank=True)
def __str__(self):
return str(self.number)
return self.name
class Meta:
verbose_name = 'Запчасть'
verbose_name_plural = 'Запчасти'

Answer 1

Your diagram looks like Parts are connected linear. The easiest way to accomplish that is to add OneToOneFields to the model it self like so:
next = models.OneToOneField('self', related_name='previous', null=True)
Then you can do something like
part = Part.object.get(name='wheel')
while part.next:
part = part.next
# At this point Part is the last part in the row
print(part)
This is the most easy way. Depending whether you have linear connections between parts only you have to adjust your fields. There is no solution to all of the graph problems unless you realize some graph structure/database which will solve common problems (I think GraphQL can do such stuff, but iam not sure). Also keep in mind that this will most probably execute one SQL query per loop iteration.