Short post covering a topic I had to spend some time figuring out. Using the Wagtail StreamField, I created a block for either an image or a video.

            
                feedback_media = StreamField(
                        blocks.StreamBlock([
                            ('image', ImageBlock()),
                            ('video', blocks.RawHTMLBlock())
                        ], max_num=1))
            
        

The ImageBlock is a custom Block that includes extra data needed about the image.

            
                class ImageBlock(StructBlock):
                    image = ImageChooserBlock(required=False)
                    alt_text = blocks.CharBlock(required=False)
                    link = blocks.URLBlock(required=False)
                    alignment = ImageFormatChoiceBlock()
                    identifier = blocks.CharBlock(required=False)