在Django 1.11 admin中创建新对象时计算只读字段

假设a为以下模型

# models.py
class Person(models.Model):
    name = models.CharField(max_length=40)
    birthdate = models.DateField()
    age = models.CharField(max_length=3) # dont mind the type, this is just an example :)

所需的行为是，在用户创建新的

Person

对象时隐藏

age

字段，并在用户提交表单时评估其值。此外，在admin中查看对象实例时，

age

字段应该可见

为了实现这一点，我创建了一个带有自定义

ModelForm

的

ModelAdmin

，如下所示

# admin.py
from django.contrib import admin
from django import forms
from .models import Person
from dateutil.relativedelta import relativedelta
import datetime

class PersonForm(forms.ModelForm):
    def clean(self):
        cleaned_data = super(PersonForm, self).clean()
        birthdate = cleaned_data.get('birthdate')
        cleaned_data['age'] = relativedelta(datetime.date.today(), birthdate).years
        return cleaned_data

class PersonAdmin(admin.ModelAdmin):
    form = PersonForm
    exclude = ('age',)

admin.site.register(Person, PersonAdmin)

---

但是，提交表单后，

age

字段不会填充，可能是因为它被排除在外。如果我删除了

排除

，则它可以工作，但表单显示的

年龄

字段不是所需的行为。

您可以使用

模型管理员

的方法代替自定义表单：

此外，您可能还可以使用：

---

或者您可以从表单中隐藏输入

# admin.py
from django.contrib import admin
from django import forms
from .models import Person
from dateutil.relativedelta import relativedelta
import datetime

class PersonForm(forms.ModelForm):
    age = forms.CharField(widget=forms.HiddenInput, required=False)
    def clean(self):
        cleaned_data = super(PersonForm, self).clean()
        birthdate = cleaned_data.get('birthdate')
        cleaned_data['age'] = relativedelta(datetime.date.today(), birthdate).years
        return cleaned_data

只有当对象为“无”（创建案例）时，才能使用该表单

---

你应该考虑一下是否真的需要一个年龄场。它需要在每个生日都有所改变。如果需要，最好通过从出生日期开始计算当前年龄的方法或属性提供。谢谢。查看对象实例时，

age

字段不可见。我将编辑我的问题以包含此内容。@Demetris正确，表单验证不会影响

age

字段。在管理中查看/编辑对象实例时，这不也会隐藏它吗？

 class PersonAdmin(admin.ModelAdmin):
    readonly_fields = ('age',)

    def save_model(self, request, obj, form, change):
        birthdate = form.cleaned_data.get('birthdate')
        age = relativedelta(datetime.date.today(), birthdate).years 
        obj.age = age
        super().save_model(request, obj, form, change)

# admin.py
from django.contrib import admin
from django import forms
from .models import Person
from dateutil.relativedelta import relativedelta
import datetime

class PersonForm(forms.ModelForm):
    age = forms.CharField(widget=forms.HiddenInput, required=False)
    def clean(self):
        cleaned_data = super(PersonForm, self).clean()
        birthdate = cleaned_data.get('birthdate')
        cleaned_data['age'] = relativedelta(datetime.date.today(), birthdate).years
        return cleaned_data

class PersonAdmin(admin.ModelAdmin):
    def get_form(self, request, obj=None, **kwargs):
        if not obj:
            kwargs['form'] = PersonForm
        return super().get_form(request, obj, **kwargs)

admin.site.register(Person, PersonAdmin)