使用 Python 读取 YAML 文件导致 AttributeError
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Reading YAML file with Python results in AttributeError
提问by Yerlan Yeszhanov
I'm trying to make a script to back up a MySQL database. I have a config.ymlfile:
我正在尝试制作一个脚本来备份 MySQL 数据库。我有一个config.yml文件：
DB_HOST :'localhost'
DB_USER : 'root'
DB_USER_PASSWORD:'P@$$w0rd'
DB_NAME : 'moodle_data'
BACKUP_PATH : '/var/lib/mysql/moodle_data'
Now I need to read this file. My Python code so far:
现在我需要阅读这个文件。到目前为止，我的 Python 代码：
import yaml
config = yaml.load(open('config.yml'))
print(config.DB_NAME)
And this is an error that comes up:
这是一个出现的错误：
file "conf.py", line 4, in <module>
print(config.DB_NAME)
AttributeError: 'str' object has no attribute 'DB_NAME'
Does anyone have an idea where I made a mistake?
有谁知道我在哪里犯了错误？
采纳答案by Roel Schroeven
There are 2 issues:
有2个问题：
- As others have said, yaml.load() loads associative arrays as mappings, so you need to use
config['DB_NAME']. - The syntax in your config file is not correct: in YAML, keys are separated from values by a colon+space.
- 正如其他人所说， yaml.load() 加载关联数组作为映射，因此您需要使用
config['DB_NAME']. - 您的配置文件中的语法不正确：在 YAML 中，键与值之间用冒号+空格分隔。
Should work if the file is formatted like this:
如果文件格式如下，应该可以工作：
DB_HOST: 'localhost'
DB_USER: 'root'
DB_USER_PASSWORD: 'P@$$w0rd'
DB_NAME: 'moodle_data'
BACKUP_PATH: '/var/lib/mysql/moodle_data'
回答by math2001
To backup your data base, you should be able to export it as a .sqlfile. If you're using a specific interface, look for Export.
要备份您的数据库，您应该能够将其导出为.sql文件。如果您使用的是特定接口，请查找Export.
Then, for Python's yaml parser.
然后，对于 Python 的 yaml 解析器。
DB_HOST :'localhost'
DB_USER : 'root'
DB_USER_PASSWORD:'P@$$w0rd'
DB_NAME : 'moodle_data'
BACKUP_PATH : '/var/lib/mysql/moodle_data'
is a key-valuething (sorry, didn't find a better word for that one). In certain langage (such as PHP I think), they are converted to objects. In python though, they are converted to dicts(yaml parser does it, JSON parser too).
是一key-value件事（对不起，没有找到更好的词来形容那个）。在某些语言中（例如我认为的 PHP），它们被转换为objects。但是在 python 中，它们被转换为dicts（yaml 解析器可以，JSON 解析器也可以）。
# access an object's attribute
my_obj.attribute = 'something cool'
my_obj.attribute # something cool
del my_obj.attribute
my_obj.attribute # error
# access a dict's key's value
my_dict = {}
my_dict['hello'] = 'world!'
my_dict['hello'] # world!
del my_dict['hello']
my_dict['hello'] # error
So, that's a really quick presentation of dicts, but that should you get you going (run help(dict), and/or have a look hereyou won't regret it)
所以，这是一个非常快速的 dicts 介绍，但是如果你让你开始（运行help(dict)，和/或看看这里你不会后悔）
In your case:
在你的情况下：
config['DB_NAME'] # moodle_data
回答by Shivkumar kondi
Try this:
尝试这个：
import yaml
with open('config.yaml', 'r') as f:
doc = yaml.load(f)
To access "DB_NAME" you can use:
要访问“DB_NAME”，您可以使用：
txt = doc["DB_NAME"]
print txt
