189 lines
4.2 KiB
Python
189 lines
4.2 KiB
Python
"""Define event classes to connect the frontend and backend."""
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from __future__ import annotations
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import inspect
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import json
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from typing import Any, Callable, Dict, List, Set, Tuple
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from pynecone.base import Base
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from pynecone.var import BaseVar, Var
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class Event(Base):
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"""An event that describes any state change in the app."""
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# The token to specify the client that the event is for.
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token: str
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# The event name.
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name: str
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# The routing data where event occurred
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router_data: Dict[str, Any] = {}
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# The event payload.
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payload: Dict[str, Any] = {}
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class EventHandler(Base):
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"""An event handler responds to an event to update the state."""
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# The function to call in response to the event.
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fn: Callable
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class Config:
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"""The Pydantic config."""
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# Needed to allow serialization of Callable.
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frozen = True
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def __call__(self, *args: Var) -> EventSpec:
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"""Pass arguments to the handler to get an event spec.
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This method configures event handlers that take in arguments.
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Args:
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*args: The arguments to pass to the handler.
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Returns:
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The event spec, containing both the function and args.
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Raises:
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TypeError: If the arguments are invalid.
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"""
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# Get the function args.
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fn_args = inspect.getfullargspec(self.fn).args[1:]
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# Construct the payload.
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values = []
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for arg in args:
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# If it is a Var, add the full name.
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if isinstance(arg, Var):
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values.append(arg.full_name)
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continue
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# Otherwise, convert to JSON.
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try:
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values.append(json.dumps(arg))
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except TypeError:
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raise TypeError(
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f"Arguments to event handlers must be Vars or JSON-serializable. Got {arg} of type {type(arg)}."
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)
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payload = tuple(zip(fn_args, values))
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# Return the event spec.
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return EventSpec(handler=self, args=payload)
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class EventSpec(Base):
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"""An event specification.
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Whereas an Event object is passed during runtime, a spec is used
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during compile time to outline the structure of an event.
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"""
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# The event handler.
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handler: EventHandler
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# The local arguments on the frontend.
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local_args: Tuple[str, ...] = ()
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# The arguments to pass to the function.
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args: Tuple[Any, ...] = ()
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class Config:
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"""The Pydantic config."""
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# Required to allow tuple fields.
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frozen = True
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class EventChain(Base):
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"""Container for a chain of events that will be executed in order."""
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events: List[EventSpec]
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class Target(Base):
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"""A Javascript event target."""
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checked: bool = False
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value: Any = None
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class FrontendEvent(Base):
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"""A Javascript event."""
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target: Target = Target()
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# The default event argument.
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EVENT_ARG = BaseVar(name="_e", type_=FrontendEvent, is_local=True)
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# Special server-side events.
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def redirect(path: str) -> Event:
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"""Redirect to a new path.
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Args:
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path: The path to redirect to.
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Returns:
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An event to redirect to the path.
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"""
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return Event(
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token="",
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name="_redirect",
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payload={"path": path},
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)
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def console_log(message: str) -> Event:
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"""Do a console.log on the browser.
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Args:
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message: The message to log.
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Returns:
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An event to log the message.
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"""
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return Event(
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token="",
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name="_console",
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payload={"message": message},
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)
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def window_alert(message: str) -> Event:
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"""Create a window alert on the browser.
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Args:
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message: The message to alert.
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Returns:
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An event to alert the message.
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"""
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return Event(
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token="",
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name="_alert",
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payload={"message": message},
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)
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# A set of common event triggers.
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EVENT_TRIGGERS: Set[str] = {
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"on_focus",
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"on_blur",
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"on_click",
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"on_context_menu",
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"on_double_click",
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"on_mouse_down",
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"on_mouse_enter",
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"on_mouse_leave",
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"on_mouse_move",
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"on_mouse_out",
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"on_mouse_over",
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"on_mouse_up",
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"on_scroll",
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}
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