在“添加”表单上将“self”选项添加到自引用外键
我有一个自我引用的ForeignKey字段：
class Thing(models.Model)
special_thing = models.ForeignKey(
'self',
blank=True,
null=True
)
在“添加东西”表格中，除了其他现有的东西，我需要提供“这件事本身”的选择，即尚未添加的东西 . 告诉用户添加然后重新访问该字段不是一种选择 .
我该怎么办呢？
我目前的想法是覆盖表格：
-
将"special_thing"从默认的ModelChoiceField更改为ChoiceField
-
将新的特殊（"marker"）选项"*** THIS THING ***"添加到__init __（）中的字段选项
-
提供clean_special_thing（），它允许"*** THIS THING ***"或可以从查询集中查找的Thing的id .
-
在save（）中，如果选择"*** THIS THING ***"，则使用special_thing = None保存Thing，然后将其设置为自身并再次保存 . 否则按照给定的ID查找Thing并像往常一样保存 .
我正在为ModelAdmin的ModelForm执行此操作 . 有没有更简单的方法？
回答(2)
2 years ago
我继续沿着这些想法前进，最后一步没有必要 . 相反，clean方法可以将选择设置为表单的实例，整体工作仍然非常合理：
from django.contrib import admin
from django import forms
from mdoels import Thing
MARKER_THIS_THING = '*** THIS THING ***'
class ThingAdmin(admin.ModelAdmin):
def get_form(self, request, obj=None, **kwargs):
"""
Return the Thing ModelForm with an additional choice for the
'special_thing' field (FK to self) that allows the Add Thing form
to refer to the newly added instance itself.
"""
form = super(ThingAdmin, self).get_form(request, obj, **kwargs)
# The form still has a ModelChoiceField for special_thing, construct
# new non-model choices from that so we can add the 'this thing' choice
thing_choices = [c for c in form.base_fields['special_thing'].choices]
if not obj:
# Only the Add form needs the special choice
thing_choices = [(MARKER_THIS_THING, MARKER_THIS_THING)] + thing_choices
form.base_fields['special_thing'] = forms.ChoiceField(
choices=thing_choices
)
def clean_special_thing(form):
"""
Now just a simple ChoiceField, convert posted values to
model instances like a ModelChoiceField does.
Convert special new 'this thing' choice to be the newly added
instance.
"""
data = form.cleaned_data['special_thing']
instance = getattr(form, 'instance', None)
if data==MARKER_THIS_THING and not (instance and instance.pk):
# Referring to new instance itself on Add form
return instance
# Return selected model like a ModelChoiceField does
try:
data = Thing.objects.get(pk=data)
except Thing.DoesNotExist:
raise forms.ValidationError('Invalid choice')
return data
# clean_* are not part of ModelAdmin, just of forms and models.
# So we attach it to the form:
form.clean_special_thing = clean_special_thing
return form
2 years ago
另一种可能的解决方案是将jQuery（example）另一个
***THIS THING***添加到模板中的formfield .提交表单后，您可以在表单的
clean-method内或视图中检查所选选项以存储它 .例如：