我正在使用django的最新版本django-mptt。这是先前状态的模型：
shop_options = (
('grocery', _('Grocery')),
('medicine', _('Medicine')),
('electronics', _('Electronics')),
('fashion', _('Fashion')),
('garden', _('Garden')),
('gift', _('Gift')),
)
class Category(MPTTModel):
name = models.CharField(max_length=50, unique=True)
name_bn = models.CharField(max_length=50, unique=True)
active = models.BooleanField(default=True)
parent = TreeForeignKey('self', null=True, blank=True, related_name='children',
db_index=True, on_delete=models.PROTECT)
slug = models.SlugField(max_length=200, db_index=True)
shop_type = models.CharField(choices=shop_options, max_length=40)
class MPTTMeta:
order_insertion_by = ['name']
class Meta:
unique_together = ('parent', 'slug',)
verbose_name_plural = 'categories'
def save(self, *args, **kwargs):
if not self.id:
# Newly created object, so set slug
self.slug = slugify(self.name)
super(Category, self).save(*args, **kwargs)
此时一切正常。然后我又添加了两个shop_options
shop_options = (
('grocery', _('Grocery')),
('medicine', _('Medicine')),
('electronics', _('Electronics')),
('fashion', _('Fashion')),
('garden', _('Garden')),
('gift', _('Gift')),
('baby_care', _('Baby Care')),
('pet_care', _('Pet Care')),
)
然后生成迁移并成功迁移此更改。现在，当我想将先前保存的类别对象从grocery / fashion（任何内容）更改为baby_care或pet_care时，它将另存为gift。
这是自动生成的迁移文件：
# Generated by Django 2.2.1 on 2019-05-08 17:12
from django.db import migrations, models
class Migration(migrations.Migration):
dependencies = [
('shop', '0074_auto_20190425_2236'),
]
operations = [
migrations.AlterField(
model_name='category',
name='shop_type',
field=models.CharField(choices=[('index', 'Index'), ('grocery', 'Grocery'), ('medicine', 'Medicine'), ('electronics', 'Electronics'), ('fashion', 'Fashion'), ('garden', 'Garden'), ('gift', 'Gift'), ('baby_care', 'Baby Care'), ('pet_care', 'Pet Care')], max_length=40),
),
migrations.AlterField(
model_name='product',
name='shop_type',
field=models.CharField(choices=[('index', 'Index'), ('grocery', 'Grocery'), ('medicine', 'Medicine'), ('electronics', 'Electronics'), ('fashion', 'Fashion'), ('garden', 'Garden'), ('gift', 'Gift'), ('baby_care', 'Baby Care'), ('pet_care', 'Pet Care')], max_length=40),
),
/// some other related models
]
此问题还导致与Category模型（例如产品模型）相关的其他模型出现相同的问题。
这是更改类别对象的视图：
def category_edit(request, pk):
cat = get_object_or_404(Category, pk=pk)
if request.method == 'POST':
category = CategoryForm(request.POST, instance=cat)
try:
parent = Category.objects.get(name=request.POST.get('parent'))
except Category.DoesNotExist:
parent = None
if category.is_valid():
category_obj = category.save(commit=False)
category_obj.parent = parent
category_obj.save()
messages.success(request, 'Category has been updated ')
else:
messages.warning(request, category.errors)
return redirect('category_create')
parent = Category.objects.filter(parent=None)
return render(request, 'admin/category/category_edit.html', {'category_list': 'active', 'parent': parent,
'category': cat, 'header': 'Edit Category'})
CategoryForm代码：
class CategoryForm(ModelForm):
class Meta:
model = Category
exclude = ('parent', 'slug')
category_edit.html：
{% extends 'admin/base.html' %}
{% block content %}
<div class="content">
<div class="card">
<div class="card-header">
<h3>{{ header }}</h3>
</div>
<div class="card-body">
{% if messages %}
{%for message in messages %}
<div class="alert alert-{{ message.tags }}" role="alert">
<ul class="messages">
<li class="text-center">{{ message }}</li>
</ul>
</div>
{% endfor %}
{% endif %}
<form action="{% url 'category_edit' pk=category.pk %}" method="post"> {% csrf_token %}
<div class="form-group">
<label>Name</label>
<input type="text" name="name" value="{{ category.name }}" class="form-control form-control-lg" placeholder="Enter category name" required>
</div>
<div class="form-group">
<label>Name Bengali</label>
<input type="text" name="name_bn" value="{{ category.name_bn }}" class="form-control form-control-lg" placeholder="Enter category name in bengali">
</div>
<div class="form-group">
<label>Shop Type</label>
<select name="shop_type" class="form-control form-control-lg" required>
<option value="grocery" {% if category.shop_type == 'grocery' %}selected {% endif %}>Grocery</option>
<option value="medicine" {% if category.shop_type == 'medicine' %}selected {% endif %} >Medicine</option>
<option value="electronics" {% if category.shop_type == 'electronics' %}selected {% endif %} >Electronics</option>
<option value="fashion" {% if category.shop_type == 'fashion' %}selected {% endif %} >Fashion</option>
<option value="garden" {% if category.shop_type == 'garden' %}selected {% endif %} >Garden</option>
<option value="gift" {% if category.shop_type == 'gift' %}selected {% endif %} >Gift</option>
<option value="gift" {% if category.shop_type == 'baby_care' %}selected {% endif %} >Baby Care</option>
<option value="gift" {% if category.shop_type == 'pet_care' %}selected {% endif %} >Pet Care</option>
</select>
</div>
<div class="form-group">
<label><strong>Active</strong></label>
<select name="active" class="form-control form-control-lg" required>
<option value="True" {% if category.active %} selected {% endif %}>Yes</option>
<option value="False" {% if not category.active %} selected {% endif %}>No</option>
</select>
</div>
<div class="form-group">
<label>Parent Category (If it is a sub category)</label>
<select name="parent" class="form-control selectpicker" data-live-search="true" >
<option {% if category.parent == 'None' %}selected {% endif %}>None selected</option>
{% for hiren in parent %}
<option value="{{ hiren.name }}" {% if category.parent.name == hiren.name %} selected {% endif %} >{{ hiren.name }}</option>
{% endfor %}
</select>
</div>
<button type="submit" class="btn btn-primary">Save</button>
</form>
</div>
</div>
</div>
{% endblock %}
答案 0 :(得分：1)
一种稍微系统化的方法：
<select name="shop_type" class="form-control form-control-lg" required>
{% for key, value in shop_options %}
<option value="{{ key }}" {% if category.shop_type == key %}selected {% endif %}>{{ value }}</option>
{% endfor %}
并将shop_options传递到模板。