Django：伪造管理界面中的字段？

问题描述

我有一个模型， Foo 。它具有几个数据库属性，以及几个基于组合因素计算出的属性。我想将这些计算出的属性呈现给用户，就好像它们是数据库属性一样。 （支持因素将被更改以反映用户输入。）是否可以通过Django管理界面来做到这一点？

I have a model, Foo. It has several database properties, and several properties that are calculated based on a combination of factors. I would like to present these calculated properties to the user as if they were database properties. (The backing factors would be changed to reflect user input.) Is there a way to do this with the Django admin interface?

推荐答案

我建议您为 Foo （FooAdminForm）子类化一个模型表单，以添加自己的字段，而该字段不受数据库支持。您的自定义验证可以驻留在ModelForm的 clean _ * 方法中。

I would suggest you subclass a modelform for Foo (FooAdminForm) to add your own fields not backed by the database. Your custom validation can reside in the clean_* methods of ModelForm.

在 save_model内部 FooAdmin 的方法获得请求， Foo 的实例以及表单数据，因此，您可以在保存实例之前/之后对数据进行所有处理。

Inside the save_model method of FooAdmin you get the request, an instance of Foo and the form data, so you could do all processing of the data before/after saving the instance.

这里是一个示例的示例，该模型具有在django admin中注册的自定义表单：

Here is an example for a model with a custom form registered with django admin:

from django import forms
from django.db import models
from django.contrib import admin


class Foo(models.Model):
    name = models.CharField(max_length=30)


class FooAdminForm(forms.ModelForm):
    # custom field not backed by database
    calculated = forms.IntegerField()

    class Meta:
        model = Foo


class FooAdmin(admin.ModelAdmin):
    # use the custom form instead of a generic modelform
    form = FooAdminForm

    # your own processing
    def save_model(self, request, obj, form, change):
        # for example:
        obj.name = 'Foo #%d' % form.cleaned_data['calculated']
        obj.save()


admin.site.register(Foo, FooAdmin)

---

根据实例数据为自定义字段提供初始值

（我不确定这是否是最好的解决方案，但它是否应该工作。）

(I'm not sure if this is the best solution, but it should work.)

为数据库中现有模型实例的模型窗体构造时，它将通过此​​实例。因此，在FooAdminForm的 __ init __ 中，可以根据实例数据更改字段属性。

When a modelform for a existing model instance in the database is constructed, it gets passed this instance. So in FooAdminForm's __init__ one can change the fields attributes based on instance data.

    def __init__(self, *args, **kwargs):
        # only change attributes if an instance is passed
        instance = kwargs.get('instance')
        if instance:
            self.base_fields['calculated'].initial = (instance.bar == 42)
        forms.ModelForm.__init__(self, *args, **kwargs)

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