153 lines
4.3 KiB
Python
153 lines
4.3 KiB
Python
"""Kanta feature demo.
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Run from the project root: python demo/main.py
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Demonstrates bootstrap, colored transaction diffs, logfmt value formatting,
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custom log headers, logging toggles, rollback, and migrations. The database
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is recreated on every run; everything else lives in this file.
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"""
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import asyncio
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import logging
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from pathlib import Path
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from types import ModuleType
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import msgspec
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from kanta import Kanta
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from kanta.logging import _ACTION, _ACTOR, _RESET, _SESSION, _TARGET
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from kanta.logging import configure_logging
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DB = Path(__file__).with_name("demo.db")
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# Fake directory: user id -> display name, resolved by the logfmt callbacks.
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USERS = {"u1": "Alice", "u2": "Bob", "u3": "Carol"}
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class DataV1(msgspec.Struct):
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"""Original schema (version 0)."""
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users: dict[str, dict] = {}
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counter: int = 0
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class Data(msgspec.Struct):
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"""Current schema: migration v1 adds the settings section."""
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users: dict[str, dict] = {}
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counter: int = 0
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settings: dict[str, str] = {}
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def migrate_v1(d: dict) -> None:
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"""Add settings section"""
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d["settings"] = {"theme": "dark"}
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migrations = ModuleType("demo_migrations")
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migrations.migrate_v1 = migrate_v1
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def add_logfmts(kanta: Kanta) -> None:
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"""Resolve user ids to display names in headers and diff paths."""
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@kanta.logfmt(path="$user")
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def resolve_actor(value: str) -> str | None:
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return USERS.get(value)
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@kanta.logfmt
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def resolve_user_key(value: str, path: str) -> str | None:
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if path.startswith("users."):
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return USERS.get(value)
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return None
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def add_header(kanta: Kanta) -> None:
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"""Aligned rich header: actor, session id, action, target."""
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@kanta.logheader
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def header(action: str, user: str | None, extra: dict | None) -> str:
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actor = f"{_ACTOR}{user or '-':<8}{_RESET}"
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session = f"{_SESSION}{extra.get('session_id', '-'):>2}{_RESET}"
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target = f"{_TARGET}{extra['target']}{_RESET}"
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return f"{actor} {session} {_ACTION}{action}{_RESET} {target}"
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async def main() -> None:
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DB.unlink(missing_ok=True)
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print("=== Standard logging: bootstrap, diffs, toggles, rollback ===", flush=True)
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kanta = Kanta(DB, DataV1())
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add_logfmts(kanta)
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@kanta.bootstrap
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def seed(data: DataV1) -> None:
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data.users["u1"] = {"name": "Alice", "role": "admin"}
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await kanta.open()
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with kanta.transaction(action="create", user="u2") as data:
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data.users["u2"] = {"name": "Bob", "role": "user"}
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with kanta.transaction(action="update", user="u1") as data:
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data.users["u2"]["role"] = "editor"
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data.counter = 1
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with kanta.transaction(action="delete", user="u1") as data:
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del data.users["u2"]
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# Display-only extra string, appended after the action.
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with kanta.transaction(action="export", user="u1", extra=DB.name) as data:
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data.counter = 2
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# Compact logging: diff only (no header) ...
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with kanta.transaction(
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action="repair", log={"header": False, "diff": True}
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) as data:
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data.users["u3"] = {"name": "Carol", "role": "user"}
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# A failing transaction rolls back and logs a warning.
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try:
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with kanta.transaction(action="reset", user="u1") as data:
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data.counter = 99
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raise ValueError("simulated failure")
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except ValueError:
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pass
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# ... and header only (no diff).
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with kanta.transaction(
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action="import", user="u1", log={"header": True, "diff": False}
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) as data:
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data.counter = 3
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await kanta.close()
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print("=== Reopen with migrations and a custom log header ===", flush=True)
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kanta = Kanta(DB, Data(), migrations=migrations)
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add_logfmts(kanta)
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add_header(kanta)
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await kanta.open()
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# No target given: defaults to the database filename.
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with kanta.transaction(action="update", user="u1", extra={"session_id": 3}) as data:
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data.settings["theme"] = "light"
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with kanta.transaction(
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action="update",
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user="u2",
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extra={"session_id": 7, "target": "settings (demo)"},
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) as data:
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data.settings["lang"] = "en"
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await kanta.close()
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print(f"=== Database written to {DB} ===", flush=True)
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if __name__ == "__main__":
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configure_logging()
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logging.getLogger("kanta").setLevel(logging.DEBUG) # show migration diffs
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asyncio.run(main())
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