def instance_from_str(instance_str):
    """
    Given an instance string in the form "app.Model:pk", returns a tuple of
    ``(model, instance)``. If the pk part is empty, ``instance`` will be
    ``None``. Raises ``ValueError`` on invalid model strings or missing
    instances.
    """
    match = instance_str_re.match(instance_str)
    if not match:
        raise ValueError("Invalid instance string")

    model_string = match.group(1)
    try:
        model = apps.get_model(model_string)
    except (LookupError, ValueError):
        raise ValueError("Invalid instance string")

    pk = match.group(2)
    if pk:
        try:
            return model, model._default_manager.get(pk=pk)
        except model.DoesNotExist:
            raise ValueError("Invalid instance string")

    return model, None
def instance_from_str(instance_str):
    """
    Given an instance string in the form "app.Model:pk", returns a tuple of
    ``(model, instance)``. If the pk part is empty, ``instance`` will be
    ``None``. Raises ``ValueError`` on invalid model strings or missing
    instances.
    """
    match = instance_str_re.match(instance_str)
    if not match:
        raise ValueError("Invalid instance string")

    model_string = match.group(1)
    try:
        model = apps.get_model(model_string)
    except (LookupError, ValueError):
        raise ValueError("Invalid instance string")

    pk = match.group(2)
    if pk:
        try:
            return model, model._default_manager.get(pk=pk)
        except model.DoesNotExist:
            raise ValueError("Invalid instance string")

    return model, None
def instance_from_str ( instance_str ) : match = instance_str_re . match ( instance_str ) if not match : raise ValueError ( "Invalid instance string" ) model_string = match . group ( 1 ) try : model = apps . get_model ( model_string ) except ( LookupError , ValueError ) : raise ValueError ( "Invalid instance string" ) pk = match . group ( 2 ) if pk : try : return model , model . _default_manager . get ( pk = pk ) except model . DoesNotExist : raise ValueError ( "Invalid instance string" ) return model , None
Given an instance string in the form "app.Model:pk", returns a tuple of
    ``(model, instance)``. If the pk part is empty, ``instance`` will be
    ``None``. Raises ``ValueError`` on invalid model strings or missing
    instances.
Given an instance string in the form app . Model : pk returns a tuple of ( model instance ) . If the pk part is empty instance will be None . Raises ValueError on invalid model strings or missing instances .