Function validate_use_pages

dash/_validate.py:508–524

(config)

def validate_use_pages(config):
    if not config.get("assets_folder", None):
        raise exceptions.PageError(
            "`dash.register_page()` must be called after app instantiation"
        )

    try:
        if get_app().backend.has_request_context():
            raise exceptions.PageError(
                """
                dash.register_page() can’t be called within a callback as it updates dash.page_registry, which is a global variable.
                For more details, see https://dash.plotly.com/sharing-data-between-callbacks#why-global-variables-will-break-your-app
                """
            )
    except exceptions.AppNotFoundError:
        # If the app is not found we can add pages since before instantiation.
        pass


def validate_module_name(module):