# documentação Django 4.0.8.dev20220803071047

# Código fonte para django.contrib.messages.api

    from django.contrib.messages import constants
    from django.contrib.messages.storage import default_storage

    __all__ = (
        "add_message",
        "get_messages",
        "get_level",
        "set_level",
        "debug",
        "info",
        "success",
        "warning",
        "error",
        "MessageFailure",
    )

    class MessageFailure(Exception):
        pass

    def add_message(request, level, message, extra_tags="", fail_silently=False):
        """
        Attempt to add a message to the request using the 'messages' app.
        """
        try:
            messages = request._messages
        except AttributeError:
            if not hasattr(request, "META"):
                raise TypeError(
                    "add_message() argument must be an HttpRequest object, not "
                    "'%s'." % request.__class__.__name__
                )
            if not fail_silently:
                raise MessageFailure(
                    "You cannot add messages without installing "
                    "django.contrib.messages.middleware.MessageMiddleware"
                )
        else:
            return messages.add(level, message, extra_tags)

    def get_messages(request):
        """
        Return the message storage on the request if it exists, otherwise return
        an empty list.
        """
        return getattr(request, "_messages", [])

    def get_level(request):
        """
        Return the minimum level of messages to be recorded.

        The default level is the ``MESSAGE_LEVEL`` setting. If this is not found,
        use the ``INFO`` level.
        """
        storage = getattr(request, "_messages", default_storage(request))
        return storage.level

    def set_level(request, level):
        """
        Set the minimum level of messages to be recorded, and return ``True`` if
        the level was recorded successfully.

        If set to ``None``, use the default level (see the get_level() function).
        """
        if not hasattr(request, "_messages"):
            return False
        request._messages.level = level
        return True

    def debug(request, message, extra_tags="", fail_silently=False):
        """Add a message with the ``DEBUG`` level."""
        add_message(
            request,
            constants.DEBUG,
            message,
            extra_tags=extra_tags,
            fail_silently=fail_silently,
        )

    def info(request, message, extra_tags="", fail_silently=False):
        """Add a message with the ``INFO`` level."""
        add_message(
            request,
            constants.INFO,
            message,
            extra_tags=extra_tags,
            fail_silently=fail_silently,
        )

    def success(request, message, extra_tags="", fail_silently=False):
        """Add a message with the ``SUCCESS`` level."""
        add_message(
            request,
            constants.SUCCESS,
            message,
            extra_tags=extra_tags,
            fail_silently=fail_silently,
        )

    def warning(request, message, extra_tags="", fail_silently=False):
        """Add a message with the ``WARNING`` level."""
        add_message(
            request,
            constants.WARNING,
            message,
            extra_tags=extra_tags,
            fail_silently=fail_silently,
        )

    def error(request, message, extra_tags="", fail_silently=False):
        """Add a message with the ``ERROR`` level."""
        add_message(
            request,
            constants.ERROR,
            message,
            extra_tags=extra_tags,
            fail_silently=fail_silently,
        )