docs:https://docs.djangoproject.com/en/1.8/topics/db/examples/many_to_many/
但是这样做也是有不便的地方:多对多字段的add()和remove()方法就不能用了。这里有很好的解释:http://stackoverflow.com/questions/1755591/many-to-many-relationships-with-additional-data-on-the-relationship https://docs.djangoproject.com/en/dev/topics/db/models/#extra-fields-on-many-to-many-relationshi...
Django admin Many-to-Many field in inlinetabular admin doesn't work for both sides of relaion Question How can I integrate m2m fields into modelAdmin, considering that this field hasthroughargument and that I can't change the DB? Or how can I use inlinetabular admin wi...
balance = models.DecimalField(max_digits=10, decimal_places=2) 在上面的例子中,User模型中的account字段是一个OneToOneField,它关联到Account模型。当一个用户被删除时,与之关联的账户也会被删除(使用on_delete=models.CASCADE)。一对多关系(One-to-Many)一对多关系是指一个模型可以有多个关联的另一个模型的实例。
Then you have two options; either allow copying, or use a many-to-many field. Because these ingredients could be changed and this needs to propogate to all meals they are a part of, I opted for the latter solution. Models and Form Code Here is the basic model code for meals, also ...
BooleanField:用于存储布尔类型DateField:用于存储日期类型DateTimeField:用于存储日期和时间类型ImageField:用于存储图片类型FileField:用于存储文件类型ForeignKey:外键 用于表示数据库表之间的关联关系OneToOneField:一对一 用于表示一对一的关联关系ManyToManyField:多对多 用于表示多对多的关联关系max_length:字段的最大长度限制...
对于像 ForeignKey 这样映射到模型实例的字段,默认应该是它们引用的字段的值(默认是 pk 除非to_field 被设置了),而不是模型实例。 当创建新的模型实例且没有为该字段提供值时,使用默认值。当字段是主键时,当字段设置为``None`` 时,也使用默认值。 editable¶ Field.editable¶ 如果是 False,该字段将不会...
some_field = 'some_value' # Save the new instance. >>> new_author.save() # Now, save the many-to-many data for the form. >>> f.save_m2m() 只有在您使用 save(commit=False) 的时候才需要调用 save_m2m() 。当您在表单上使用 save() 时,无需调用其他方法,所有数据(包括多对多数据)...
ValueError:"<Pizza: Pepperoni>"needstohaveavalueforfield"id"beforethismany-to-manyrelationshipcanbeused. This error is more explicit (it states that an id is required) but it's essentially the same error. It's just coming from the other side of the relationship. ...
http://docs.djangoproject.com/en/dev/ref/contrib/admin/#working-with-many-to-many-intermediary-models(trunk) citing: "...when you specify an intermediary model using the through argument to a ManyToManyField, the admin will not display a widget by default. This is because each instance ...