#正向查找:boyret=models.UserInfo.objects.filter(name='liang1').first()print(boyret,'boyret--------') boyret1=boyret.m.all()#通过本表的外键查询到的是 UserInfo object,如果是all() 那就是<QuerySet [<UserInfo: UserInfo object>, <
# Generic Foreign Key Fields content_type=models.ForeignKey(ContentType) object_id=models.PositiveIntegerField(_('object ID')) content_object=generic.GenericForeignKey() # Hierarchy Field parent=models.ForeignKey('self', null=True, blank=True, default=None, related_name='children') # User Field ...
Number = models.IntegerField(unique=True,blank=False, null=False) Gender = models.ForeignKey('Coding',on_delete=models.CASCADE) # 关联Coding表格 ForeignKey (othermodel,on_delete,**options) 有两个必选的参数 : 第一个参数:关联的表格(主表),在默认的情况下,外键储存的是主表的主键(Primary key)。
4.1 实现方法 PrimaryKeyRelatedField+嵌套序列化器 PrimaryKeyRelatedField是序列化器字段中，主键相关字...
By convention, Django appends "_id" to the foreign key field name. (Yes, you can override this, as well.) The foreign key relationship is made explicit by a FOREIGN KEY constraint. Don’t worry about the DEFERRABLE parts; it’s telling PostgreSQL to not enforce the foreign key until the...
): """ 删除时会引起 ProtectedError,不删除关联表的内容 :param collector: :param field: :param sub_objs: :param using: :return: """ raise ProtectedError( "Cannot delete some instances of model '%s' because they are " "referenced through a protected foreign key: '%s.%s'" % ( field....
If the field is a ForeignKey, Django will display the __str__() of the related object. ManyToManyField fields aren’t supported, because that would entail executing a separate SQL statement for each row in the table. If you want to do this nonetheless, give your model a custom method, ...
问django:预取GenericForeignKey的相关对象ENcontenttypes 是Django内置的一个应用，可以追踪项目中所有app和...
So, let’s bridge this gap and allow using foreign key protection with data stored in JSON fields! Models First, you have to start using the django-json-schema-editor and specifically its JSONField instead of the standard Django JSONField. The most important difference between those two ...
Basic DB table is: class ModelA(models.Model): type_of_input = models.CharField(max_length=10) # say "USER" or "SOURCE" date = models.DateField() volume = models.IntegerField() object_referenced = Foreign_key... Problem We sometimes have two duplicate entries in ...