[英]How to set initial value in a dynamic Django ModelChoiceField?
I'm trying to create a simple page versioning system for a website.我正在尝试为网站创建一个简单的页面版本控制系统。 I want to be able to pass a page into a form, which points to all of the versions related to the page, and have the form dropdown contain all of the versions for that page, and make the initial page version the ideal version when it is initialized in the view.我希望能够将一个页面传递到一个表单中,该表单指向与该页面相关的所有版本,并让表单下拉列表包含该页面的所有版本,并使初始页面版本成为理想版本在视图中初始化。 So far, the form will fill with all of the versions for the page, but not select the ideal version as the initial item.到目前为止,表单将填写页面的所有版本,但不会选择理想版本作为初始项。
How do I set the initial item of a field in a form if the field gets populated while the form is initialized in the view?如果在视图中初始化表单时填充了字段,如何设置表单中字段的初始项?
Research:研究:
I have tried the answers in the following questions, but none of them had the solution:我已经尝试了以下问题的答案,但没有一个有解决方案:
Example code:示例代码:
models.py模型.py
from django.db import models
from autoslug import AutoSlugField
from django_enumfield import enum
from ..users.models import User
def write_page(name, submitter, content=''):
page = Page.objects.get_or_create(name=name)[0]
page_version = PageVersion.create(page, submitter, content)
return page_version
class Status(enum.Enum):
DISABLED = 0
ACTIVE = 1
class Page(models.Model):
name = models.CharField(max_length=100)
slug = AutoSlugField(populate_from='name', unique=True)
status = enum.EnumField(Status, default=Status.ACTIVE)
current_version = models.IntegerField(default=0)
def __unicode__(self):
name_str = "(name='{}', slug='{}')"
return name_str.format(self.name, self.slug)
@property
def versions(self):
status = ("status = {}".format(Status.ACTIVE),)
order_by = ("-version",)
return self.pageversion_set.extra(where=status, order_by=order_by)
@property
def all_versions(self):
order_by = ("-version",)
return self.pageversion_set.extra(order_by=order_by)
@property
def ideal(self):
try:
return PageVersion.objects.get(id=self.current_version)
except self.DoesNotExist:
return None
@property
def version(self):
if self.ideal:
return self.ideal.version
return 0
@property
def content(self):
if self.ideal:
return self.ideal.content
return ''
@property
def submitter(self):
if self.ideal:
return self.ideal.submitter
return None
@classmethod
def create(cls, name):
page_object = cls.objects.create(name=name)
return page_object
class PageVersion(models.Model):
parent = models.ForeignKey(Page)
version = models.IntegerField(default=0)
content = models.TextField()
date = models.DateTimeField(auto_now_add=True)
status = enum.EnumField(Status, default=Status.ACTIVE)
submitter = models.ForeignKey(User)
def __unicode__(self):
name_str = "(name='{}', slug='{}', version={})"
return name_str.format(self.name, self.slug, self.version)
@property
def name(self):
return self.parent.name
@property
def slug(self):
return self.parent.slug
@classmethod
def create(cls, page, submitter, content='', make_current=True):
if page.all_versions:
current_max_version = max([i.version for i in page.all_versions])
else:
current_max_version = 0
page_version_object = cls(parent=page, submitter=submitter, content=content)
page_version_object.version = current_max_version + 1
page_version_object.save()
if make_current:
page.current_version = page_version_object.id
page.save()
return page_version_object
forms.py表格.py
from django import forms
from .models import PageVersion
class PageVersionForm(forms.Form):
version = forms.ModelChoiceField(queryset=None)
def __init__(self, *args, **kwargs):
page = kwargs.pop("page")
super(PageVersionForm, self).__init__(*args, **kwargs)
self.fields["version"].queryset = page.versions
views.py视图.py
from django.shortcuts import get_object_or_404, render
from django.http import HttpResponseRedirect, HttpResponseForbidden
from django.core.urlresolvers import reverse
from .models import Page, write_page
from .forms import PageForm, PageVersionForm
from ..helpers import get_pages
def update_page(request, slug):
if not request.user.has_perm("can_edit_page"):
return HttpResponseForbidden()
page = get_object_or_404(Page, slug=slug)
if request.method == "POST":
form = PageForm(request.POST)
if form.is_valid():
content = form.cleaned_data["content"]
user = request.user
write_page(name=page.name, submitter=user, content=content)
kwargs = {}
kwargs["slug"] = slug
return HttpResponseRedirect(reverse("pages:detail", kwargs=kwargs))
else:
data = {}
data["content"] = page.content
form = PageForm(data)
context = {}
page_version_form = PageVersionForm(page=page)
context["form"] = form
context["page_version_form"] = page_version_form
context["page"] = page
context["user"] = request.user
context.update(get_pages())
return render(request, "pages/page_update.html", context)
You need to reset choices
property as it is cached on the field once queryset is set and is not revalidated even if you update queryset
property.您需要重置choices
属性,因为一旦设置了queryset,它就会缓存在字段上,即使您更新queryset
属性也不会重新验证。
def __init__(self, *args, **kwargs):
...
self.fields['version'].queryset = page.versions
self.fields['version'].widget.choices = self.fields['version'].choices
Can you check if ModelChoiceField
in your Django version has a setter method named _set_queryset
?你能检查一下你的 Django 版本中的ModelChoiceField
是否有一个名为_set_queryset
的 setter 方法吗? It seems to be fixed in github.它似乎已在github中修复。
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