如何使用Django模型从Wagtail CMS Stream字段面板中获取值？

from django.db import models
from wagtail.core import blocks
from wagtail.core.fields import StreamField
from wagtail.core.models import Page
from wagtail.admin.edit_handlers import FieldPanel, StreamFieldPanel

class MyPage(Page):
    stream_field = StreamField([
        ('text', blocks.RichTextBlock()),
        ('image', blocks.ImageChooserBlock()),
    ])

    content_panels = Page.content_panels + [
        StreamFieldPanel('stream_field'),
    ]

    def get_stream_field_value(self):
        return self.stream_field.stream_data

from django.shortcuts import render
from .models import MyPage

def my_view(request):
    page = MyPage.objects.first()
    stream_field_value = page.get_stream_field_value()
    return render(request, 'my_template.html', {'stream_field_value': stream_field_value})

<!-- my_template.html -->
{% for block in stream_field_value %}
    {% if block.block_type == 'text' %}
        <p>{{ block.value }}</p>
    {% elif block.block_type == 'image' %}
        <img src="{{ block.value.url }}" alt="{{ block.value.alt }}">
    {% endif %}
{% endfor %}