Allow publishing of updates to live pages to be optional

[SociologicalReview]

In the current version of generate_qr_code in wagtail_qrcode/wagtail_hooks.py the last two lines cause draft changes to live pages to be automatically published:

def generate_qr_code(request, page):
    """Add a QR code to the page."""

    # dont try to generate a qrcode if the page does not inherit from QRCodeMixin
    if is_qrcode_instance(page):
        collection = create_collection("QR Codes")

        qrc = WagtailQrCode(page, collection)

        svg, document = qrc.build()

        page.qr_code_svg = svg
        page.qr_code_eps = document

        rev = page.save_revision()

        if page.live:
            rev.publish()

It is quite common for someone to draft changes to a page but want to hold off on publishing them, for example, if they are gradually updating a page or needing approval from another editor. Generally, it would be up to the page editor to choose when to publish a page rather than this being enforced in code.

This update introduces a setting, WAGTAIL_QR_CODE_AUTO_PUBLISH_UPDATES, which allows this behaviour to be optional.

• If set to False, the default behaviour, pages are not automatically published after editing.
• If set to True, the pages are published, as in the original version.

The default is taken as False as this is more in line with common procedure.

def generate_qr_code(request, page):
    """Add a QR code to the page."""

    # dont try to generate a qrcode if the page does not inherit from QRCodeMixin
    if is_qrcode_instance(page):
        collection = create_collection("QR Codes")

        qrc = WagtailQrCode(page, collection)

        svg, document = qrc.build()

        page.qr_code_svg = svg
        page.qr_code_eps = document

        rev = page.save_revision()

        if (
            page.live
            and getattr(settings, "WAGTAIL_QR_CODE_AUTO_PUBLISH_UPDATES", False) == True
        ):
            rev.publish()

This references issue #60