五個常見的Django錯誤

from django.contrib.auth import get_user_modelfrom django.core.exceptions import ValidationErrorfrom django.db import models
User = get_user_model()

class Organization(models.Model):    name = models.CharField(max_length=100)    datetime_created = models.DateTimeField(auto_now_add=True, editable=False)    is_active = models.BooleanField(default=True)

class Employee(models.Model):    user = models.ForeignKey(        User, on_delete=models.CASCADE, related_name="employees"    )    organization = models.ForeignKey(        Organization, on_delete=models.CASCADE, related_name="employees"    )    is_currently_employed = models.BooleanField(default=True)    reference_id = models.CharField(null=True, blank=True, max_length=255)    last_clock_in = models.DateTimeField(null=True, blank=True)    datetime_created = models.DateTimeField(auto_now_add=True, editable=False)
def clean(self):try:if self.last_clock_in < self.datetime_created:raise ValidationError("Last clock in must occur after the employee entered"" the system."                )except TypeError:# Raises TypeError if there is no last_clock_in because# you cant compare None to datetimepass

for org in Organization.objects.filter(is_active=True):for emp in org.employees.all():if emp.is_currently_employed:            do_something(org, emp)

for org in Organization.objects.filter(is_active=True).prefetch_related(    "employees"):

for emp in Employee.objects.filter(    organization__is_active=True, is_currently_employed=True).select_related("organization"):    do_something(emp.organization, emp)

reference_id = models.CharField(null=True, blank=True, max_length=255)

if employee.reference_id is not None:    fetch_employee_record(employee)

oldest_organization_first = Organization.objects.order_by("datetime_created")
newest_organization_first = Organization.objects.order_by("-datetime_created")

oldest_organization_first = Organization.objects.latest("-datetime_created")
newest_organization_first = Organization.objects.latest("datetime_created")

>>> oldest_org = Organization.objects.order_by("datetime_created")[:1][0]>>> oldest_other_org = Organization.objects.latest("-datetime_created")>>> oldest_org == oldest_other_orgTrue
>>> newest_org = Organization.objects.order_by("-datetime_created")[:1][0]>>> newest_other_org = Organization.objects.latest("datetime_created")>>> newest_org == newest_other_orgTrue

def clean(self):try:if self.last_clock_in < self.datetime_created:raise ValidationError("Last clock in must occur after the employee entered"" the system."            )except TypeError:# Raises TypeError if there is no last_clock_in because# you cant compare None to datetimepass

from django.http import HttpResponsefrom django.shortcuts import get_object_or_404from django.views.decorators.http import require_http_methods
from example_project.helpers import parse_requestfrom example_project.models import Employee

@require_http_methods(["POST"])def update_employee_last_clock_in(request, employee_pk):    clock_in_datetime = parse_request(request)    employee = get_object_or_404(Employee, pk=employee_pk)    employee.last_clock_in = clock_in_datetime    employee.save()return HttpResponse(status=200)

employee.last_clock_in = clock_in_datetimeemployee.full_clean()employee.save()

>>> user = User.objects.get(id=1)>>> user.first_name = "Steven">>> user.save()UPDATE "users_user"   SET "password" = 'some_hash',"last_login" = '2021-02-25T22:43:41.033881+00:00'::timestamptz,"is_superuser" = false,"username" = 'stevenapate',"first_name" = 'Steven',"last_name" = '',"email" = '[email protected]',"is_staff" = false,"is_active" = true,"date_joined" = '2021-02-19T21:08:50.885795+00:00'::timestamptz, WHERE "users_user"."id" = 1>>> user.first_name = "NotSteven">>> user.save(update_fields=["first_name"])UPDATE "users_user"   SET "first_name" = 'NotSteven' WHERE "users_user"."id" = 1

from celery import taskfrom django.contrib.auth import get_user_model
from example_project.external_api import get_user_status
User = get_user_model()

@taskdef update_user_status(user_pk):    user = User.objects.get(pk=user_pk)    user_status = get_user_status(user)if user_status == "inactive":        user.is_active = False        user.save()

if user_status == "inactive":    user.is_active = False    user.save(update_fields=["is_active"])