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signals

Signals and SignalEmitter that gathers the signals on models Meta. Used to signal receivers functions about events, i.e. post_save, pre_delete etc.

Signal

Signal that notifies all receiver functions. In ormar used by models to send pre_save, post_save etc. signals.

Source code in ormar/signals/signal.py
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class Signal:
    """
    Signal that notifies all receiver functions.
    In ormar used by models to send pre_save, post_save etc. signals.
    """

    def __init__(self) -> None:
        self._receivers: Dict[Union[int, Tuple[int, int]], Callable] = {}

    def connect(self, receiver: Callable) -> None:
        """
        Connects given receiver function to the signal.

        :raises SignalDefinitionError: if receiver is not callable
        or not accept **kwargs
        :param receiver: receiver function
        :type receiver: Callable
        """
        if not callable(receiver):
            raise SignalDefinitionError("Signal receivers must be callable.")
        if not callable_accepts_kwargs(receiver):
            raise SignalDefinitionError(
                "Signal receivers must accept **kwargs argument."
            )
        new_receiver_key = make_id(receiver)
        if new_receiver_key not in self._receivers:
            self._receivers[new_receiver_key] = receiver

    def disconnect(self, receiver: Callable) -> bool:
        """
        Removes the receiver function from the signal.

        :param receiver: receiver function
        :type receiver: Callable
        :return: flag if receiver was removed
        :rtype: bool
        """
        new_receiver_key = make_id(receiver)
        receiver_func: Union[Callable, None] = self._receivers.pop(
            new_receiver_key, None
        )
        return True if receiver_func is not None else False

    async def send(self, sender: Type["Model"], **kwargs: Any) -> None:
        """
        Notifies all receiver functions with given kwargs
        :param sender: model that sends the signal
        :type sender: Type["Model"]
        :param kwargs: arguments passed to receivers
        :type kwargs: Any
        """
        receivers = [
            receiver_func(sender=sender, **kwargs)
            for receiver_func in self._receivers.values()
        ]
        await asyncio.gather(*receivers)

connect(receiver)

Connects given receiver function to the signal.

Parameters:

Name Type Description Default
receiver Callable

receiver function

required

Raises:

Type Description
SignalDefinitionError

if receiver is not callable or not accept **kwargs

Source code in ormar/signals/signal.py
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def connect(self, receiver: Callable) -> None:
    """
    Connects given receiver function to the signal.

    :raises SignalDefinitionError: if receiver is not callable
    or not accept **kwargs
    :param receiver: receiver function
    :type receiver: Callable
    """
    if not callable(receiver):
        raise SignalDefinitionError("Signal receivers must be callable.")
    if not callable_accepts_kwargs(receiver):
        raise SignalDefinitionError(
            "Signal receivers must accept **kwargs argument."
        )
    new_receiver_key = make_id(receiver)
    if new_receiver_key not in self._receivers:
        self._receivers[new_receiver_key] = receiver

disconnect(receiver)

Removes the receiver function from the signal.

Parameters:

Name Type Description Default
receiver Callable

receiver function

required

Returns:

Type Description
bool

flag if receiver was removed

Source code in ormar/signals/signal.py
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def disconnect(self, receiver: Callable) -> bool:
    """
    Removes the receiver function from the signal.

    :param receiver: receiver function
    :type receiver: Callable
    :return: flag if receiver was removed
    :rtype: bool
    """
    new_receiver_key = make_id(receiver)
    receiver_func: Union[Callable, None] = self._receivers.pop(
        new_receiver_key, None
    )
    return True if receiver_func is not None else False

send(sender, **kwargs) async

Notifies all receiver functions with given kwargs

Parameters:

Name Type Description Default
sender Type['Model']

model that sends the signal

required
kwargs Any

arguments passed to receivers

required
Source code in ormar/signals/signal.py
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async def send(self, sender: Type["Model"], **kwargs: Any) -> None:
    """
    Notifies all receiver functions with given kwargs
    :param sender: model that sends the signal
    :type sender: Type["Model"]
    :param kwargs: arguments passed to receivers
    :type kwargs: Any
    """
    receivers = [
        receiver_func(sender=sender, **kwargs)
        for receiver_func in self._receivers.values()
    ]
    await asyncio.gather(*receivers)

SignalEmitter

Bases: dict

Emitter that registers the signals in internal dictionary. If signal with given name does not exist it's auto added on access.

Source code in ormar/signals/signal.py
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class SignalEmitter(dict):
    """
    Emitter that registers the signals in internal dictionary.
    If signal with given name does not exist it's auto added on access.
    """

    def __getattr__(self, item: str) -> Signal:
        return self.setdefault(item, Signal())

    def __setattr__(self, key: str, value: Signal) -> None:
        if not isinstance(value, Signal):
            raise SignalDefinitionError(f"{value} is not valid signal")
        self[key] = value