Django：从ModelAdmin内访问模型实例？ [英] Django: accessing the model instance from within ModelAdmin?

问题描述

我在网上商店应用程序中有一个订单模型，自动递增主键和一个外键自身，因为订单可以分为多个订单，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

我已经为管理员网站注册了一个OrderAdmin类。对于详细视图，我在 fieldsets 属性中包含 parent_order 。当然，默认情况下，这会列出选择框中的所有订单，但这不是所需的行为。相反，对于没有父级订单的订单（即没有从其他订单分割; parent_order 为NULL / None），则不应显示任何订单。对于已经拆分的订单，这仅应显示单个父级订单。

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queryset可以在其​​中过滤。想象一下，我们正在查看订单＃11234的详细视图，它已从订单＃11208拆分。代码在

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)

注释的行在运行于Python shell，返回一个包含＃11234的订单＃11208的单项查询器，以及可能从中拆分的所有其他订单。

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，我们不能硬编码在那里的订单号。我们需要引用订单实例的 ordernumber 字段，其详细信息页面正在查看。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=?????)

我发现没有办法替代参考当前订单实例，我已经挖了很深。 self in formfield_for_foreignkey 是指ModelAdmin实例，而确实有一个模型属性，它不是订单模型实例（它是一个ModelBase引用; self.model（）返回一个实例，但其顺序号为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).

一个解决方案可能是从request.path（/ admin / orders / order / 11234 /）中提取订单号，但这真的很丑陋。我真的希望有一个更好的方法。

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

我认为你可能需要以稍微不同的方式来处理这个 - 通过修改ModelForm，而不是admin类。这样的东西：

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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