Arguments that are dependent on other arguments with Argparse
Question:
I want to accomplish something like this:
-LoadFiles
-SourceFile "" -DestPath ""
-SourceFolder "" -DestPath ""
-GenericOperation
-SpecificOperation -Arga "" -Argb ""
-OtherOperation -Argc "" -Argb "" -Argc ""
A user should be able to run things like:
-LoadFiles -SourceFile "somePath" -DestPath "somePath"
or
-LoadFiles -SourceFolder "somePath" -DestPath "somePath"
Basically, if you have -LoadFiles
, you are required to have either -SourceFile
or -SourceFolder
after. If you have -SourceFile
, you are required to have -DestPath
, etc.
Is this chain of required arguments for other arguments possible? If not, can I at least do something like, if you have -SourceFile
, you MUST have -DestPath
?
Answers:
Here is a sample that in case you specify –makeDependency, forces you to specify –dependency with a value as well.
This is not done by argparse alone, but also by by the program that later on validates what the user specified.
#!/usr/bin/env python
import argparse
import sys
parser = argparse.ArgumentParser()
parser.add_argument('--makeDependency', help='create dependency on --dependency', action='store_true')
parser.add_argument('--dependency', help='dependency example')
args = parser.parse_args()
if args.makeDependency and not args.dependency:
print "error on dependency"
sys.exit(1)
print "ok!"
After you call parse_args
on the ArgumentParser
instance you’ve created, it’ll give you a Namespace
object. Simply check that if one of the arguments is present then the other one has to be there too. Like:
args = parser.parse_args()
if ('LoadFiles' in vars(args) and
'SourceFolder' not in vars(args) and
'SourceFile' not in vars(args)):
parser.error('The -LoadFiles argument requires the -SourceFolder or -SourceFile')
There are some argparse
alternatives which you can easily manage cases like what you mentioned.
packages like:
click or
docopt.
If we want to get around the manual implementation of chain arguments in argparse, check out the Commands and Groups in click for instance.
You can use subparsers in argparse
import argparse
parser = argparse.ArgumentParser(prog='PROG')
parser.add_argument('--foo', required=True, help='foo help')
subparsers = parser.add_subparsers(help='sub-command help')
# create the parser for the "bar" command
parser_a = subparsers.add_parser('bar', help='a help')
parser_a.add_argument('bar', type=int, help='bar help')
print(parser.parse_args())
I want to accomplish something like this:
-LoadFiles
-SourceFile "" -DestPath ""
-SourceFolder "" -DestPath ""
-GenericOperation
-SpecificOperation -Arga "" -Argb ""
-OtherOperation -Argc "" -Argb "" -Argc ""
A user should be able to run things like:
-LoadFiles -SourceFile "somePath" -DestPath "somePath"
or
-LoadFiles -SourceFolder "somePath" -DestPath "somePath"
Basically, if you have -LoadFiles
, you are required to have either -SourceFile
or -SourceFolder
after. If you have -SourceFile
, you are required to have -DestPath
, etc.
Is this chain of required arguments for other arguments possible? If not, can I at least do something like, if you have -SourceFile
, you MUST have -DestPath
?
Here is a sample that in case you specify –makeDependency, forces you to specify –dependency with a value as well.
This is not done by argparse alone, but also by by the program that later on validates what the user specified.
#!/usr/bin/env python
import argparse
import sys
parser = argparse.ArgumentParser()
parser.add_argument('--makeDependency', help='create dependency on --dependency', action='store_true')
parser.add_argument('--dependency', help='dependency example')
args = parser.parse_args()
if args.makeDependency and not args.dependency:
print "error on dependency"
sys.exit(1)
print "ok!"
After you call parse_args
on the ArgumentParser
instance you’ve created, it’ll give you a Namespace
object. Simply check that if one of the arguments is present then the other one has to be there too. Like:
args = parser.parse_args()
if ('LoadFiles' in vars(args) and
'SourceFolder' not in vars(args) and
'SourceFile' not in vars(args)):
parser.error('The -LoadFiles argument requires the -SourceFolder or -SourceFile')
There are some argparse
alternatives which you can easily manage cases like what you mentioned.
packages like:
click or
docopt.
If we want to get around the manual implementation of chain arguments in argparse, check out the Commands and Groups in click for instance.
You can use subparsers in argparse
import argparse
parser = argparse.ArgumentParser(prog='PROG')
parser.add_argument('--foo', required=True, help='foo help')
subparsers = parser.add_subparsers(help='sub-command help')
# create the parser for the "bar" command
parser_a = subparsers.add_parser('bar', help='a help')
parser_a.add_argument('bar', type=int, help='bar help')
print(parser.parse_args())