Typeerror: ‘required’ is an invalid argument for positionals

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As a developer, encountering errors while coding is a common occurrence. One such error is the TypeError: ‘required’ is an invalid argument for positionals.

So in this article, we will explore this error message in detail, understand its causes, and learn how to fix it.

Let’s understand first what are positional arguments in Python.

In Python, arguments are passed to a function in the order they are defined.

What is typeerror: ‘required’ is an invalid argument for positional?

The error TypeError: ‘required’ is an invalid argument for positionals means that you have passed a required argument as a positional argument.

In Python, positional arguments are arguments that are passed to a function based on their position or order, whereas keyword arguments are passed based on their name.

Causes of ‘required’ is an invalid argument for positional

The most common cause of this error is when a required argument is passed as a positional argument.

Here is the code to reproduce the error:

import argparse

parser = argparse.ArgumentParser()
parser.add_argument('name', required=True)
args = parser.parse_args()

print(args.name)

This error occurs because the required argument is not a valid argument for a positional argument.

Solutions to typeerror ‘required’ is an invalid argument for positional

Here are three ways to fix this error:

  1. Use a keyword argument instead of a positional argument:
import argparse

parser = argparse.ArgumentParser()
parser.add_argument('--name', required=True)
args = parser.parse_args()

print(args.name)

Output:

$ python script.py --name John
John

  1. Add the required argument as a keyword argument to the add_argument() method:
import argparse

parser = argparse.ArgumentParser()
parser.add_argument('name', required=True)
args = parser.parse_args()

print(args.name)

should be changed to:

import argparse

parser = argparse.ArgumentParser()
parser.add_argument('name', required=True, help='Name argument is required')
args = parser.parse_args()

print(args.name)

Output:

$ python script.py --name John
John

  1. Remove the required argument from the add_argument() method:

import argparse

parser = argparse.ArgumentParser()
parser.add_argument('name')
args = parser.parse_args()

print(args.name)

Output:

$ python script.py John
John

Conclusion

In this article, we explored the TypeError: ‘required’ is an invalid argument for positionals error message, its causes, and solutions. It is important to remember that this error occurs when a required argument is passed as a positional argument. The solutions include providing a value for the missing argument or making the missing argument optional by providing a default value.

We hope that this article has helped you resolve this error and that you can now continue working on your Python projects without any issues.

If you are finding solutions to some errors you might encounter we also have Typeerror: can’t compare offset-naive and offset-aware datetimes.

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