制作一个 Django model class 其字段值之一由其他模型的字段值计算，并且它必须存在于我的实际数据库表中

Question

models.py

from django.db import models

class model_A(models.Model):
  value_1 = models.IntegerField()
  value_2 = models.FloatField()

class model_B(modles.Model):
  value_3 = models.FloatField()
  value_4 = (model_A.value_1 - model_B.value_2)

admin.py

from django.contrib import admin

# Register your models here.
from .models import model_A, model_B

model_lst = [model_A, model_B]

for i in model_lst:
    admin.site.register(i)

I want model_B to have value_4 as separate column in database table(model_B)

Answer 1

For this purpose, you can use computedfield:

https://pypi.org/project/django-computedfields/