调试(显示)SQLAlchemy 发送到数据库的 SQL 命令 [英] Debugging (displaying) SQL command sent to the db by SQLAlchemy

问题描述

我有一个名为 Person 的 ORM 类，它环绕一个人表:

I have an ORM class called Person, which wraps around a person table:

建立与数据库等的连接后，我运行语句:

After setting up the connection to the db etc, I run the statement:

people = session.query(Person).all()

person 表不包含任何数据(到目前为止)，所以当我打印变量 people 时，我得到一个空列表.

The person table does not contain any data (as yet), so when I print the variable people, I get an empty list.

我将 ORM 类 People 中引用的表重命名为 people_foo(不存在).

I renamed the table referred to in my ORM class People, to people_foo (which does not exist).

然后我再次运行脚本.我很惊讶在尝试访问不存在的表时没有抛出异常.

I then run the script again. I was surprised that no exception was thrown when attempting to access a table that does not exist.

因此我有以下两个问题:

I therefore have the following 2 questions:

1. 如何设置 SQLAlchemy 以便将数据库错误传播回脚本?
2. 如何查看(即打印)发送到数据库引擎的 SQL?

如果有帮助，我正在使用 PostgreSQL.

If it helps, I am using PostgreSQL.

我正在写一个包.在我的 __main__.py 脚本中，我有以下代码(此处缩短):

I am writing a package. In my __main__.py script, I have the following code (shortened here):

### __main__.py
import common # imports logging and defines logging setup funcs etc

logger = logging.getLogger(__name__)


def main():    
    parser = OptionParser(usage="%prog [options] <commands>",
                          version="%prog 1.0")

    commands = OptionGroup(parser, "commands")

    parser.add_option(
        "-l",
        "--logfile",
        dest="logfile",
        metavar="FILE",
        help="log to FILE. if not set, no logging will be done"
    )

    parser.add_option(
        "--level",
        dest="loglevel",
        metavar="LOG LEVEL",
        help="Debug level. if not set, level will default to low"
    )

    # Set defaults if not specified
    if not options.loglevel:
        loglevel = 1
    else:
        loglevel = options.loglevel

    if not options.logfile:
        logfilename = 'datafeed.log'
    else:
        logfilename = options.logfile

    common.setup_logger(False, logfilename, loglevel) 

       # and so on ...



        #### dbfuncs.py


import logging

    # not sure how to 'bind' to the logger in __main__.py
    logging.getLogger('sqlalchemy.engine').setLevel(logging.INFO)

    engine = create_engine('postgres://postgres:pwd@localhost:port/dbname', echo=True)

Common 模块正确设置了记录器，我可以在导入 common 的其他模块中使用记录器.

Common module sets the logger up correctly, and I can use the logger in my other modules that import common.

但是在 dbfuncs 模块中，我收到以下错误/警告:

However in dbfuncs module, I am getting the following error/warning:

找不到记录器sqlalchemy.engine.base.Engine"的处理程序

No handlers could be found for logger "sqlalchemy.engine.base.Engine

推荐答案

除了 create_engine() 的 echo 参数之外，还有一种更灵活的方式:配置 logging 以回显引擎语句:

In addition to echo parameter of create_engine() there is a more flexible way: configuring logging to echo engine statements:

import logging
logging.basicConfig()
logging.getLogger('sqlalchemy.engine').setLevel(logging.INFO)

请参阅文档的配置日志记录部分了解更多信息信息.

See Configuring Logging section of documentation for more information.

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