如何使用django表单显示带有预选数据的选择字段？

from django import forms

class MyForm(forms.Form):
    CHOICES = (
        ('option1', 'Option 1'),
        ('option2', 'Option 2'),
        ('option3', 'Option 3'),
    )
    my_field = forms.ChoiceField(choices=CHOICES)

from django.shortcuts import render
from .forms import MyForm

def my_view(request):
    form = MyForm()
    return render(request, 'my_template.html', {'form': form})

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