SQLAlchemy 报告 BINARY 列的 "Invalid utf8mb4 character string"

Question

假设此 MySQL table 架构：

CREATE TABLE `user` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `uuid` binary(16) NOT NULL,
  `email` varchar(255) NOT NULL,
  `name` varchar(255) DEFAULT NULL,
  `photo` binary(16) DEFAULT NULL,
  PRIMARY KEY (`id`),
  UNIQUE KEY `uuid` (`uuid`),
  UNIQUE KEY `email` (`email`)
) ENGINE=InnoDB AUTO_INCREMENT=8 DEFAULT CHARSET=utf8mb4;

当我这样使用来自 SQLAlchemy 连接 class 的 execute() API 时：

with self.engine.begin() as connection:
  user_uuid = uuid.UUID("...")
  result = connection.execute("SELECT email, name, photo FROM user WHERE uuid=%s", user_uuid.bytes)

如果 UUID 是 F393A167-A919-4B50-BBB7-4AD356E89E6B，则 SQLAlchemy 会打印此警告：

/site-packages/sqlalchemy/engine/default.py:450: Warning: Invalid utf8mb4 character string: 'F393A1'

uuid 列是 BINARY 列，那么为什么 SQLAlchemy 将此参数视为文本参数而不是二进制参数？如何防止这种情况？

Answer 1

解释和解决其实就在这个bug report in MySQL:

replace:

cursor.execute(""" INSERT INTO user (uuid) VALUES (%s) """, my_uuid)

with

cursor.execute(""" INSERT INTO user (uuid) VALUES (_binary %s) """, my_uuid)

Mind the underscore. It's "_binary", not "binary". This "_binary" tells MySQL that the following string is to be interpreted as binary, not to be interpreted/validated as utf8.

Answer 2

问题在 Python 3 上没有发生，所以我认为问题是数据库驱动程序无法区分给定 Python 2 str类型。

无论如何，似乎直接使用 SQLAlchemy 核心工作正常，大概是因为它直接知道列类型。

from sqlalchemy import MetaData, Table, select

meta = MetaData()
user = Table('user', meta, autoload_with=engine)
result = select([user]).where(user.c.uuid == user_uuid.bytes)

如果你想继续执行一个字符串，你可以转换为字节数组，就像 SQLAlchemy 似乎在做的那样：

with self.engine.begin() as connection:
    user_uuid = uuid.UUID("...")
    result = connection.execute(
        "SELECT email, name, photo FROM user WHERE uuid=%s",
        bytearray(user_uuid.bytes))

或者告诉 SQLAlchemy 绑定参数是什么类型来自动获取它：

from sqlalchemy import text, bindparam, BINARY

with self.engine.begin() as connection:
    user_uuid = uuid.UUID("...")
    stmt = text("SELECT email, name, photo FROM user WHERE uuid = :uuid")
    stmt = stmt.bindparams(bindparam('uuid', user_uuid.bytes, type_=BINARY))
    result = connection.execute(stmt)

SQLAlchemy 报告 BINARY 列的 "Invalid utf8mb4 character string"

SQLAlchemy reports "Invalid utf8mb4 character string" for BINARY column

sqlalchemy

mysql-python