CODEWITHSUNDEEP
pythonargparse
user6090578
user6090578

Reputation:

argparse error: 'nargs must be %r to supply const' % OPTIONAL)

I keep getting the error: raise ValueError('nargs must be %r to supply const' % OPTIONAL) when I use the following code in python:

parser = argparse.ArgumentParser()
parser.add_argument('--username', type=str, required=True,
                    help="Username to login. Required")
parser.add_argument('--password', type=str, required=True,
                    help="Password to login. Required.")

parser.add_argument('--chromedriver', type=str, const=r'C:\histdata\batfiles\chromedriver.exe')
parser.add_argument('--output', type=str, const='C:\\histdata\\batfiles\\')

It fails on the line for --chromedriver. When I move the next line before it to test that too. It fails. That is --output line gives the same error. I realize that people in the past have posted a similar error message, but I still don't see how to fix it.

Upvotes: 2

Views: 1813

Answers (1)

Евгений Крамаров
Евгений Крамаров

Reputation: 499

Maybe you want to use default instead of const? The former is used to store the default value of an argument, the latter is for specifying const value, that will be stored, when the argument is provided.

Upvotes: 1

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