e8387c8e26
* Fix Event chaining in the on_load event handler return not working * added async tests * addressed comments
82 lines
2.7 KiB
Python
82 lines
2.7 KiB
Python
"""Middleware to hydrate the state."""
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from __future__ import annotations
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from typing import TYPE_CHECKING, Dict, List, Optional, Union
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from pynecone import constants
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from pynecone.event import Event, EventHandler, get_hydrate_event
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from pynecone.middleware.middleware import Middleware
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from pynecone.state import State, StateUpdate
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from pynecone.utils import format
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if TYPE_CHECKING:
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from pynecone.app import App
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class HydrateMiddleware(Middleware):
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"""Middleware to handle initial app hydration."""
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async def preprocess(
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self, app: App, state: State, event: Event
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) -> Optional[Union[StateUpdate, List[StateUpdate]]]:
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"""Preprocess the event.
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Args:
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app: The app to apply the middleware to.
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state: The client state.
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event: The event to preprocess.
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Returns:
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An optional delta or list of state updates to return.
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"""
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if event.name == get_hydrate_event(state):
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route = event.router_data.get(constants.RouteVar.PATH, "")
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if route == "/":
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load_event = app.load_events.get(constants.INDEX_ROUTE)
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elif route:
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load_event = app.load_events.get(route.lstrip("/"))
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else:
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load_event = None
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if load_event:
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if not isinstance(load_event, List):
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load_event = [load_event]
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updates = []
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for single_event in load_event:
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updates.append(
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await self.execute_load_event(
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state, single_event, event.token, event.payload
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)
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)
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return updates
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delta = format.format_state({state.get_name(): state.dict()})
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return StateUpdate(delta=delta) if delta else None
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async def execute_load_event(
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self, state: State, load_event: EventHandler, token: str, payload: Dict
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) -> StateUpdate:
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"""Execute single load event.
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Args:
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state: The client state.
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load_event: A single load event to execute.
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token: Client token
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payload: The event payload
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Returns:
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A state Update.
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Raises:
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ValueError: If the state value is None.
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"""
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substate_path = format.format_event_handler(load_event).split(".")
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ex_state = state.get_substate(substate_path[:-1])
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if not ex_state:
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raise ValueError(
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"The value of state cannot be None when processing an on-load event."
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)
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return await state.process_event(
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handler=load_event, state=ex_state, payload=payload, token=token
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)
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