Route meta¶

Override a route's meta method to return a dictionary of page metadata. The router calls it before loading data, so use its loader arguments rather than relying on routing_context.data.

from routing.router import Route


class ProductRoute(Route):
    path = "/product"
    form = "Pages.Product"

    def meta(self, **loader_args):
        return {
            "title": "Product page",
            "description": "Details and specifications for our product.",
            "og:image": "asset:product.jpeg",
            "twitter:card": "summary_large_image",
        }

Asset URLs¶

Use asset:product.jpeg to refer to an app theme asset. To construct an absolute URL yourself, use anvil.server.get_app_origin():

import anvil.server
from routing.router import Route


class AboutRoute(Route):
    path = "/about"
    form = "Pages.About"

    def meta(self, **loader_args):
        origin = anvil.server.get_app_origin()
        return {
            "title": "About us",
            "description": "Information about our company and team.",
            "og:image": f"{origin}/_/theme/about.jpeg",
        }

Client and server behaviour¶

On a direct URL request, the router passes the metadata to Anvil's AppResponder, which controls the initial response's metadata. On client navigation, the router updates the document's <title> and writes metadata as <meta name="..." content="..."> elements, including Open Graph names such as og:image.

The client supports arbitrary names, including Twitter card tags. A tag appearing after client navigation does not establish that it is present in the initial HTML read by a social preview crawler. Check the initial response when validating previews.

Defaults¶

The base Route.meta method returns {}. On the client:

• title updates both <title> and <meta name="title">.
• og:title and og:description use title and description when those values are supplied without their Open Graph equivalents.
• When a tag is omitted, the current implementation restores the value captured before its most recent explicit update. This can restore metadata from an earlier route, so explicitly supply values that must be consistent across navigation. A newly created tag starts with an empty value.

See the Route class for the rest of the route lifecycle.