wagtail_bakerydemo/bakerydemo/base/blocks.py

from django.utils.functional import cached_property
from wagtail.blocks import (
    CharBlock,
    ChoiceBlock,
    RichTextBlock,
    StreamBlock,
    StructBlock,
    TextBlock,
)
from wagtail.embeds.blocks import EmbedBlock
from wagtail.images import get_image_model
from wagtail.images.blocks import ImageChooserBlock


def get_image_api_representation(image):
    return {
        "id": image.pk,
        "title": image.title,
        "meta": {
            "type": type(image)._meta.label,
            "download_url": image.file.url,
        },
    }


class CaptionedImageBlock(StructBlock):
    """
    Custom `StructBlock` for utilizing images with associated caption and
    attribution data
    """

    image = ImageChooserBlock(required=True)
    caption = CharBlock(required=False)
    attribution = CharBlock(required=False)

    @cached_property
    def preview_image(self):
        # Cache the image object for previews to avoid repeated queries
        return get_image_model().objects.last()

    def get_preview_value(self):
        return {
            **self.meta.preview_value,
            "image": self.preview_image,
            "caption": self.preview_image.description,
        }

    def get_api_representation(self, value, context=None):
        data = super().get_api_representation(value, context)
        data["image"] = get_image_api_representation(value["image"])
        return data

    class Meta:
        icon = "image"
        template = "blocks/captioned_image_block.html"
        preview_value = {"attribution": "The Wagtail Bakery"}
        description = "An image with optional caption and attribution"


class HeadingBlock(StructBlock):
    """
    Custom `StructBlock` that allows the user to select h2 - h4 sizes for headers
    """

    heading_text = CharBlock(classname="title", required=True)
    size = ChoiceBlock(
        choices=[
            ("", "Select a header size"),
            ("h2", "H2"),
            ("h3", "H3"),
            ("h4", "H4"),
        ],
        blank=True,
        required=False,
    )

    class Meta:
        icon = "title"
        template = "blocks/heading_block.html"
        preview_value = {"heading_text": "Healthy bread types", "size": "h2"}
        description = "A heading with level two, three, or four"


class BlockQuote(StructBlock):
    """
    Custom `StructBlock` that allows the user to attribute a quote to the author
    """

    text = TextBlock()
    attribute_name = CharBlock(blank=True, required=False, label="e.g. Mary Berry")

    class Meta:
        icon = "openquote"
        template = "blocks/blockquote.html"
        preview_value = {
            "text": (
                "If you read a lot you're well read / "
                "If you eat a lot you're well bread."
            ),
            "attribute_name": "Willie Wagtail",
        }
        description = "A quote with an optional attribution"


# StreamBlocks
class BaseStreamBlock(StreamBlock):
    """
    Define the custom blocks that `StreamField` will utilize
    """

    heading_block = HeadingBlock()
    paragraph_block = RichTextBlock(
        icon="pilcrow",
        template="blocks/paragraph_block.html",
        preview_value=(
            """
            <h2>Our bread pledge</h2>
            <p>As a bakery, <b>breads</b> have <i>always</i> been in our hearts.
            <a href="https://en.wikipedia.org/wiki/Staple_food">Staple foods</a>
            are essential for society, and – bread is the tastiest of all.
            We love to transform batters and doughs into baked goods with a firm
            dry crust and fluffy center.</p>
            """
        ),
        description="A rich text paragraph",
    )
    image_block = CaptionedImageBlock()
    block_quote = BlockQuote()
    embed_block = EmbedBlock(
        help_text="Insert an embed URL e.g https://www.youtube.com/watch?v=SGJFWirQ3ks",
        icon="media",
        template="blocks/embed_block.html",
        preview_template="base/preview/static_embed_block.html",
        preview_value="https://www.youtube.com/watch?v=mwrGSfiB1Mg",
        description="An embedded video or other media",
    )