Question

来自psycopg2上的PostgreSQL docs：

当已经在事务块内部时发出BEGIN将激发a 警告信息。交易状态不受影响。

如何让let allMedia = PHAsset.fetchAssetsWithOptions(fetchOptions) let allPhotos = PHAsset.fetchAssetsWithMediaType(.Image, options: fetchOptions) let allVideo = PHAsset.fetchAssetsWithMediaType(.Video, options: fetchOptions) print("Found \(allMedia.count) media") print("Found \(allPhotos.count) images") print("Found \(allVideo.count) videos")针对任何此类警告提出异常？

Answer 1

我离psycopg2或Postgres专家很远，而且我确信有更好的解决方案来提高警告级别，但这里有一些对我有用的东西 - {{3调查a custom cursor，如果有什么东西 - 它会抛出异常。实现本身主要用于教育目的 - 我确信需要调整它以适应您的用例：

import psycopg2

# this "cursor" class needs to be used as a base for custom cursor classes
from psycopg2.extensions import cursor  

class ErrorThrowingCursor(cursor):
    def __init__(self, conn, *args, **kwargs):
        self.conn = conn
        super(ErrorThrowingCursor, self).__init__(*args, **kwargs)

    def execute(self, query, vars=None):
        result = super(ErrorThrowingCursor, self).execute(query, vars)

        for notice in self.conn.notices:
            level, message = notice.split(": ")
            if level == "WARNING":
                raise psycopg2.Warning(message.strip())

        return result

使用示例：

conn = psycopg2.connect(user="user", password="secret")
cursor = conn.cursor(conn, cursor_factory=ErrorThrowingCursor)

如果在执行查询后发出警告，则会抛出异常（connection notices类型）。样品：

psycopg2.Warning: there is already a transaction in progress

如何在psycopg2中向异常提升PostgreSQL警告？

1 个答案: