为 Python argparse 输入参数指定日期格式 [英] Specify date format for Python argparse input arguments

问题描述

我有一个需要一些命令行输入的 Python 脚本，我正在使用 argparse 来解析它们.我发现文档有点混乱，找不到检查输入参数格式的方法.这个示例脚本解释了我检查格式的意思:

I have a Python script that requires some command line inputs and I am using argparse for parsing them. I found the documentation a bit confusing and couldn't find a way to check for a format in the input parameters. What I mean by checking format is explained with this example script:

parser.add_argument('-s', "--startdate", help="The Start Date - format YYYY-MM-DD ", required=True)
parser.add_argument('-e', "--enddate", help="The End Date format YYYY-MM-DD (Inclusive)", required=True)
parser.add_argument('-a', "--accountid", type=int, help='Account ID for the account for which data is required (Default: 570)')
parser.add_argument('-o', "--outputpath", help='Directory where output needs to be stored (Default: ' + os.path.dirname(os.path.abspath(__file__)))

我需要检查选项 -s 和 -e 用户输入的格式为 YYYY-MM-DD.argparse 中是否有我不知道的选项可以完成此操作?

I need to check for option -s and -e that the input by the user is in the format YYYY-MM-DD. Is there an option in argparse that I do not know of which accomplishes this?

推荐答案

Per 文档:

add_argument() 的 type 关键字参数允许执行任何必要的类型检查和类型转换...... type 的参数> 可以是任何接受单个字符串的可调用对象.

The type keyword argument of add_argument() allows any necessary type-checking and type conversions to be performed ... The argument to type can be any callable that accepts a single string.

你可以这样做:

def valid_date(s):
    try:
        return datetime.strptime(s, "%Y-%m-%d")
    except ValueError:
        msg = "not a valid date: {0!r}".format(s)
        raise argparse.ArgumentTypeError(msg)

然后将其用作 type:

parser.add_argument(
    "-s", 
    "--startdate", 
    help="The Start Date - format YYYY-MM-DD", 
    required=True, 
    type=valid_date
)

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