Django:从 ModelAdmin 中访问模型实例? [英] Django: accessing the model instance from within ModelAdmin?
问题描述
我有一个网上商店应用程序中的订单模型，具有自动递增的主键和自身的外键，因为订单可以拆分为多个订单，但必须保持与原始订单的关系.
I've got a model for Orders in a webshop application, with an auto-incrementing primary key and a foreign key to itself, since orders can be split into multiple orders, but the relationship to the original order must be maintained.
class Order(models.Model):
ordernumber = models.AutoField(primary_key=True)
parent_order = models.ForeignKey('self', null=True, blank=True, related_name='child_orders')
# .. other fields not relevant here
我已经为管理站点注册了一个 OrderAdmin 类.对于详细视图，我在 fieldsets 属性中包含了 parent_order.当然，默认情况下，这会在选择框中列出所有订单，但这不是所需的行为.相反，对于没有父订单的订单(即没有从另一个订单拆分；parent_order 为 NULL/None)，不应显示任何订单.对于已拆分的订单，这应该只显示单父订单.
I've registered an OrderAdmin class for the admin site. For the detail view, I've included parent_order in the fieldsets attribute. Of course, by default this lists all the orders in a select box, but this is not the desired behaviour. Instead, for orders that don't have a parent order (i.e. have not been split from another order; parent_order is NULL/None), no orders should be displayed. For orders that have been split, this should only display the single parent order.
有一个相当新的 ModelAdmin 方法可用，formfield_for_foreignkey，这似乎是完美的，因为可以在其中过滤查询集.假设我们正在查看订单#11234 的详细视图，该订单已从订单#11208 中拆分出来.代码如下
There's a rather new ModelAdmin method available, formfield_for_foreignkey, that seems perfect for this, since the queryset can be filtered inside it. Imagine we're looking at the detail view of order #11234, which has been split from order #11208. The code is below
def formfield_for_foreignkey(self, db_field, request, **kwargs):
if db_field.name == 'parent_order':
# kwargs["queryset"] = Order.objects.filter(child_orders__ordernumber__exact=11234)
return db_field.formfield(**kwargs)
return super(OrderAdmin, self).formfield_for_foreignkey(db_field, request, **kwargs)
注释行在 Python shell 中运行时有效，返回一个单项查询集，其中包含订单 #11208 和 #11234 以及所有其他可能已从中拆分的订单.
The commented row works when run in a Python shell, returning a single-item queryset containing order #11208 for #11234 and all other orders that may have been split from it.
当然，我们不能在那里对订单号进行硬编码.我们需要引用我们正在查看其详细信息页面的订单实例的 ordernumber 字段.像这样:
Of course, we can't hard-code the order number there. We need a reference to the ordernumber field of the order instance whose detail page we're looking at. Like this:
kwargs["queryset"] = Order.objects.filter(child_orders__ordernumber__exact=?????)
我没有找到替换的有效方法??????参考当前" Order 实例，我已经深入挖掘了.formfield_for_foreignkey 中的 self 指的是 ModelAdmin 实例，虽然它确实具有 model 属性，但它不是订单模型实例(它是 ModelBase 引用; self.model() 返回一个实例，但它的 ordernumber 是 None).
I've found no working way to replace ????? with a reference to the "current" Order instance, and I've dug pretty deep. self inside formfield_for_foreignkey refers to the ModelAdmin instance, and while that does have a model attribute, it's not the order model instance (it's a ModelBase reference; self.model() returns an instance, but its ordernumber is None).
一种解决方案可能是从 request.path (/admin/orders/order/11234/) 中提取订单号，但这真的很难看.我真的希望有更好的方法.
One solution might be to pull the order number from request.path (/admin/orders/order/11234/), but that is really ugly. I really wish there is a better way.
推荐答案
我认为您可能需要以稍微不同的方式来解决这个问题 - 通过修改 ModelForm 而不是管理类.像这样的:
I think you might need to approach this in a slightly different way - by modifying the ModelForm, rather than the admin class. Something like this:
class OrderForm(forms.ModelForm):
def __init__(self, *args, **kwargs):
super(OrderForm, self).__init__(*args, **kwargs)
self.fields['parent_order'].queryset = Order.objects.filter(
child_orders__ordernumber__exact=self.instance.pk)
class OrderAdmin(admin.ModelAdmin):
form = OrderForm
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