(django)当基于用户的角色创建用户时，我想创建一个指定的模型实例

# models.py
from django.db import models

class UserRole(models.Model):
    role_name = models.CharField(max_length=50)

class User(models.Model):
    username = models.CharField(max_length=50)
    role = models.ForeignKey(UserRole, on_delete=models.CASCADE)

# forms.py
from django import forms

class UserForm(forms.Form):
    username = forms.CharField(max_length=50)
    role = forms.ModelChoiceField(queryset=UserRole.objects.all())

# views.py
from django.shortcuts import render, redirect
from .forms import UserForm
from .models import User

def create_user(request):
    if request.method == 'POST':
        form = UserForm(request.POST)
        if form.is_valid():
            username = form.cleaned_data['username']
            role = form.cleaned_data['role']
            user = User.objects.create(username=username, role=role)
            return redirect('success')
    else:
        form = UserForm()
    return render(request, 'create_user.html', {'form': form})

# create_user.html
<form method="post">
  {% csrf_token %}
  {{ form.as_p }}
  <button type="submit">Create User</button>
</form>