Django模型字段类型怎么选？一文搞懂常用字段选项

class ForeignKey(to, on_delete, **options)

from django.db import models

class Manufacturer(models.Model):
    # ...
    pass

class Car(models.Model):
    manufacturer = models.ForeignKey(Manufacturer, on_delete=models.CASCADE)
    # ...

manufacturer = models.ForeignKey(Manufacturer, on_delete=models.RESTRICT)

manufacturer = models.ForeignKey(Manufacturer, on_delete=models.PROTECT)

manufacturer = models.ForeignKey(Manufacturer, on_delete=models.RESTRICT)

manufacturer = models.ForeignKey(Manufacturer, on_delete=models.SET_NULL,null=True)

manufacturer = models.ForeignKey(Manufacturer, on_delete=models.SET_DEFAULT default=1)

#定义一个函数进行值得返回
def get_manufacturer()
	return 1

manufacturer = models.ForeignKey(Manufacturer, on_delete=models.SET(get_manufacturer),)

manufacturer = models.ForeignKey(Manufacturer, on_delete=models.DO_NOTHING)

#模型创建  model.py
class District(models.Model):
    parent = models.ForeignKey(
        "self",
        null=True,
        blank=True,
        on_delete=models.CASCADE,
        related_name="child", #
        verbose_name="父级地区",
    )
    name = models.CharField(max_length=128, help_text="地区名称", verbose_name="地区名称")
    level = models.IntegerField(default=0, help_text="地区级别", verbose_name="地区级别")
    full_name = models.CharField(max_length=256, help_text="地区全名", verbose_name="地区全名")
    def __str__(self):
        return self.full_name
    class Meta:
        managed=True
        verbose_name = "地区信息"
        verbose_name_plural = verbose_name

#视图调用模型以drf框架的视图的使用APIView主
class CityCountyView(APIView):
    """
    父级下二级地区信息获取
    """
    authentication_classes = [BasicAuthentication]
    permission_classes = (AllowAny,)
    @swagger_auto_schema(operation_description='父级下二级地区信息获取', responses={200: {}})
    def get(self, request, pk):
        # 判断有没有缓存，有缓存使用缓存，没有缓存去数据库查询存入缓存一天
        sub_data = cache.get('sub_data_%s' % pk)
        if not sub_data:
            try:
                # 获取到前端传过来的父级id  查询出父级对象
                parent_obj = District.objects.get(id=pk)
                # 获取对象的所有外键关联的子级
                sub_objs = parent_obj.child.all()
                subs = []
                # 组织数据
                for sub in sub_objs:
                    subs.append({'id': sub.id, 'name': sub.name, })
                sub_data = {'id': pk, 'name': parent_obj.name, 'subs': subs}
            except Exception as e:
                print(e)
                return Response({'code': 400, 'errmsg': '查询失败'})
            cache_key_name = 'sub_data_%s' % pk
            cache.set(cache_key_name, sub_data, 3600 * 24) #
        return Response({'code': 0, 'errmsg': 'ok', 'sub_data': sub_data})

#使用函数+class来定义
def getTaskDetailModel(table_name):
    class MyCLass(models.Model):
        task = models.ForeignKey(Task, on_delete=models.CASCADE, related_name='details', verbose_name='任务')
        user_id = models.IntegerField(verbose_name='用户ID')
        created_time = models.DateTimeField(auto_now_add=True, verbose_name='创建时间')
        is_complet = models.BooleanField(default=False, verbose_name='是否完成')
        class Meta:
            db_table = table_name

    return MyCLass

#使用函数+type进行创建动态类
def create_task_detail_model(password_code):
    classname = f'TaskDetail_{password_code}'
    class Meta:
        db_table = classname

    return type(classname, (models.Model,), {
        'task': models.ForeignKey(Task, on_delete=models.CASCADE, related_name='details', verbose_name='任务'),
        'user_id': models.IntegerField(verbose_name='用户ID'),
        'created_time': models.DateTimeField(auto_now_add=True, verbose_name='创建时间'),
        'is_complet': models.BooleanField(default=False, verbose_name='是否完成'),
        '__str__': lambda self: f"{self.task.password_code} - {self.user_id}",
        'Meta': Meta,
        '__module__': __name__,
    })