Click: "Got unexpected extra arguments" when passing string

Figured this out. Instead of just calling a function, I must pass a context and call it from there:

@cli.command()
@click.pass_context
def run():
    for namespace in KEYS.iterkeys():
        ctx.invoke(process, namespace=namespace)

From the docs:

Sometimes, it might be interesting to invoke one command from another command. This is a pattern that is generally discouraged with Click, but possible nonetheless. For this, you can use the Context.invoke() or Context.forward() methods.

They work similarly, but the difference is that Context.invoke() merely invokes another command with the arguments you provide as a caller, whereas Context.forward() fills in the arguments from the current command. Both accept the command as the first argument and everything else is passed onwards as you would expect.

Example:

cli = click.Group()

@cli.command()
@click.option('--count', default=1)
def test(count):
    click.echo('Count: %d' % count)

@cli.command()
@click.option('--count', default=1)
@click.pass_context
def dist(ctx, count):
    ctx.forward(test)
    ctx.invoke(test, count=42)

And what it looks like:

$ cli dist
Count: 1
Count: 42

I got this error when calling a same name method with the click method:

@cli.command()
@click.argument("namespace", nargs=1)
def process(namespace):
    process("foo")  # <---- HERE

Fixed it by rename one of them, hope it helps for others!

tl;dr Remove whitespace from your arguments.

If anyone else is going through the same and above answer does not clarify or work for you probably you are in my condition.

To me this error was being caused because I had given arguments having space in between and the function/module accepting it wasn't allowed to take space separated input, hence the rest of the input name was being taken as separate arguments causing

"Got unexpected extra arguments" error.