使用ManyToManyField的Django自定义表单:如何从web添加新项

from django.db import models

class Item(models.Model):
    name = models.CharField(max_length=100)

class Category(models.Model):
    name = models.CharField(max_length=100)
    items = models.ManyToManyField(Item)

from django import forms
from .models import Category

class CategoryForm(forms.ModelForm):
    class Meta:
        model = Category
        fields = ['name', 'items']

from django.shortcuts import render, redirect
from .forms import CategoryForm

def add_category(request):
    if request.method == 'POST':
        form = CategoryForm(request.POST)
        if form.is_valid():
            form.save()
            return redirect('category_list')
    else:
        form = CategoryForm()
    return render(request, 'add_category.html', {'form': form})

def category_list(request):
    categories = Category.objects.all()
    return render(request, 'category_list.html', {'categories': categories})

<form method="post">
  {% csrf_token %}
  {{ form.as_p }}
  <button type="submit">添加</button>
</form>

{% for category in categories %}
  <h2>{{ category.name }}</h2>
  <ul>
    {% for item in category.items.all %}
      <li>{{ item.name }}</li>
    {% endfor %}
  </ul>
{% endfor %}