Question

所以我试图有问题地创建实例，但我不断收到此错误。当我尝试makemigrations时，错误发生在最后一行rec.save（）上。没有rec.save（）行，它工作正常。我已经尝试过Users.objects.create_user（username =“xy”，password =“password123”），并且还刷新了取出rec.save（）行的数据库。

django.db.utils.IntegrityError：NOT NULL约束失败：catalog_company.modif ied_by_id

这是我的代码

from django.db import models
from django.contrib.auth.models import User, UserManager
from datetime import date
import datetime
from django.urls import reverse #Used to generate URLs by reversing the URL 
patterns
from django.core.validators import MaxLengthValidator
from simple_history.models import HistoricalRecords
from simple_history import register

register(User, inherit=True)


class Company(models.Model):
"""
Model representing a company invested in.
"""
    name = models.CharField(max_length=200) 

    #details
    group=models.CharField(max_length=15, default='EQD')
    stake = models.CharField(max_length=50, blank=True)
    partners = models.CharField(max_length=50, blank=True)

    #user details
    modified_by = models.ForeignKey(User,related_name='Project_modified_by')
    modified_date = models.DateTimeField(auto_now=True)

    #to keep records
    history = HistoricalRecords(inherit=True)

    def __str__(self):
        """
        String for representing the Model object.
        """
        return self.name

    def get_form_url(self):
        """
        Returns the url to access the form to change model attributes.
        """
        return reverse('forms', args=[str(self.id)])

    def attrsetter(self,attr,value):
         """
         set attribute of an instance
         """
         return setattr(self, attr, value)

    @property
    def _history_user(self): #to track who modified
        return self.modified_by

    @_history_user.setter  #to track what was modified
    def _history_user(self, value):
        self.modified_by = value


rec = Company(name='ABC',modified_date=datetime.datetime.now().date())
rec.save()

Answer 1

所以我设法做到了。我必须创建一个名为＆＃34; admin＆＃34;的超级用户。第一

然后根据我的代码，modified_by字段不为null所以我需要给用户一个。以下作品

adminuser = User.objects.get(username='admin')
rec = Company(name='ABC',modified_date=datetime.datetime.now().date(),modified_by= adminuser)
rec.save()

但这会带来另一个问题，即每次运行代码时，它都会创建另一个实例。 createsuperuser
makemigrations
迁移
的runserver ..
所以需要加入适当的if子句

Django无法创建实例

1 个答案: