问题：指定输入参数argparse python的格式
我有一个需要一些命令行输入的python脚本，并且我正在使用argparse进行解析。我发现文档有点混乱，找不到在输入参数中检查格式的方法。这个示例脚本解释了我检查格式的意思：
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并且-e用户输入的格式为YYYY-MM-DD。我不知道argparse中有一个选项可以完成此任务。
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__)))
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.
回答 0
根据文档：
的type关键字参数add_argument()允许执行任何必要的类型检查和类型转换… type=可以接受带有单个字符串参数并返回转换后值的任何可调用对象
您可以执行以下操作：
def valid_date(s):
try:
return datetime.strptime(s, "%Y-%m-%d")
except ValueError:
msg = "Not a valid date: '{0}'.".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)
Per the documentation:
The type keyword argument of add_argument() allows any necessary type-checking and type conversions to be performed … type= can take any callable that takes a single string argument and returns the converted value
You could do something like:
def valid_date(s):
try:
return datetime.strptime(s, "%Y-%m-%d")
except ValueError:
msg = "Not a valid date: '{0}'.".format(s)
raise argparse.ArgumentTypeError(msg)
Then use that as type:
parser.add_argument("-s",
"--startdate",
help="The Start Date - format YYYY-MM-DD",
required=True,
type=valid_date)
回答 1
只是为了补充上面的答案，如果您想将lambda函数保持为单一格式，则可以使用该函数。例如：
parser.add_argument('--date', type=lambda d: datetime.strptime(d, '%Y%m%d'))
旧线程，但问题至少仍然与我有关！
Just to add on to the answer above, you can use a lambda function if you want to keep it to a one-liner. For example:
parser.add_argument('--date', type=lambda d: datetime.strptime(d, '%Y%m%d'))
Old thread but the question was still relevant for me at least!
回答 2
对于其他通过搜索引擎实现此目标的人：在Python 3.7中，您可以使用标准的.fromisoformatclass方法，而不是为ISO-8601兼容日期重新发明轮子，例如：
parser.add_argument('-s', "--startdate",
help="The Start Date - format YYYY-MM-DD",
required=True,
type=datetime.date.fromisoformat)
parser.add_argument('-e', "--enddate",
help="The End Date format YYYY-MM-DD (Inclusive)",
required=True,
type=datetime.date.fromisoformat)
For others who hit this via search engines: in Python 3.7, you can use the standard .fromisoformat class method instead of reinventing the wheel for ISO-8601 compliant dates, e.g.:
parser.add_argument('-s', "--startdate",
help="The Start Date - format YYYY-MM-DD",
required=True,
type=datetime.date.fromisoformat)
parser.add_argument('-e', "--enddate",
help="The End Date format YYYY-MM-DD (Inclusive)",
required=True,
type=datetime.date.fromisoformat)
