Keep the market-hours database when a refresh returns malformed JSON

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@pcbeingused333 已经在做这个了。

开始于 2026年11月4日。

  • #710 来自 @pcbeingused333 —— 未关闭

评估

难度
3/5
预计耗时
1-2 天
新手友好度
35/100
Issue 类型
缺陷
描述清晰度
描述清楚
活跃度
停滞
技术栈
python
领域
cli, databases, testing

调研方向

Read lean/components/cloud/data_downloader.py and lean/components/util/market_hours_database.py to trace the download, file replacement, refresh timestamp, and JSON reader behavior. Check the existing tests for these components, then add the described regression case with a valid cached database and malformed response. Done means invalid content leaves the prior database usable and refresh is recorded only after a successful update. An open linked pull request (#710) is already against this issue.

由索引模型根据 Issue 内容生成。

描述

Problem

On master (d812d26), a successful HTTP response containing malformed JSON can overwrite a usable local market-hours database. Subsequent database reads fail instead of retaining the last valid data.

The path is:

  • DataDownloader.update_database_files() (lean/components/cloud/data_downloader.py:83-92) downloads the market-hours database and passes its bytes directly to _store_local_file.
  • DataClient.download_public_file() (lean/components/api/data_client.py:89-95) returns raw response content, without JSON validation.
  • _store_local_file() (lean/components/cloud/data_downloader.py:24-27) opens the existing file with wb+ and writes those bytes.
  • MarketHoursDatabase._get_all_entries() (lean/components/util/market_hours_database.py:63-69) only parses the JSON when it is later read.

The refresh timestamp is also recorded before the download/write (data_downloader.py:85), so a malformed successful response can leave the bad file in place until the next configured refresh interval.

Synthetic reproduction

With the CLI installed and initialized, this uses only a temporary file, not an actual data directory:

import json
import tempfile
from pathlib import Path
from lean.components.cloud.data_downloader import _store_local_file

with tempfile.TemporaryDirectory() as directory:
    cache = Path(directory) / "market-hours-database.json"
    previous = '{"entries": {}}'
    cache.write_text(previous, encoding="utf-8")

    # Bytes returned by a malformed HTTP 200 response.
    _store_local_file(b"not json", cache)
    print(cache.read_text(encoding="utf-8"))  # not json; valid data is lost
    json.loads(cache.read_text(encoding="utf-8"))  # JSONDecodeError

I verified the same result using the isolated _store_local_file function from master: the file becomes not json, and the next decode raises JSONDecodeError. This is a synthetic malformed response, not a report that the hosted database is currently malformed.

Suggested fix

Validate the downloaded market-hours content using the format accepted by its reader (including supported comments and the required entries structure) before replacing the local file. Write through a temporary file, preserve the existing file's access metadata, and replace only after validation and writing succeed. Record a successful refresh only after it completes. Add a regression test with a pre-existing valid database and a malformed successful response.

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