how to pass optional parameters into a function in python?

Question

I have a function which I want to pass two optional parameters. I have read through but somehow I am not able to make it work though.

What am I missing here?

I have something like this

def json_response_message(status, message, option_key, option_value):
    data = {
        'status': status,
        'message': message,
    }
    if option_key:
        data[option_key] = option_value
    return JsonResponse(data)

the last two parameters I want it to be optional.

I have seen there it can be done by doing

def json_response_message(status, message, option_key='', option_value=''):

but I don't really want to do it this way and saw that there is a way to pass *args and **kwargs but it couldn't get it to work though.

I am just stuck at putting the optional parameters but not sure how to call and use them. I read through some posts and its' easily be done and call by using a for loop but somehow it just didn't work for me

def json_response_message(status, message, *args, **kwargs):
    data = {
        'status': status,
        'message': message,
    }

    return JsonResponse(data)

I want add extra parameters into my data return such as...

    user = {
        'facebook': 'fb',
        'instagram': 'ig'
    }

    return json_response_message(True, 'found', 'user', user)

Which of these two is your expected output? {'status': status, 'message': message, 'user': { 'facebook': 'fb', 'instagram': 'ig'} } or {'status': status, 'message': message, 'facebook': 'fb', 'instagram': 'ig'} (i.e. you want to append optional parameter to response as dictionary or do you want to return flat structure, but add multiple key-value pairs through optional function args)? — Mirek Długosz
– Mirek Długosz, Commented Apr 14, 2017 at 23:53

juanpa.arrivillaga · Accepted Answer · 2017-04-14 23:57:22Z

2

You want something like this, I suppose:

def json_response_message(status, message, options=()):
    data = {
    'status': status,
    'message': message,
    }

    # assuming options is now just a dictionary or a sequence of key-value pairs
    data.update(options)

    return data

And you can use it like this:

user = {
    'facebook': 'fb',
    'instagram': 'ig'
}
print(json_response_message(True, 'found', user))

answered Apr 14, 2017 at 23:57

juanpa.arrivillaga

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5 Comments

Max Power Over a year ago

this is a better answer than mine, I suggest going with this.

Dora Over a year ago

this is superb, just something came into my mind. is there possible way to put more than one dictionary in? like having two / three options or more?

juanpa.arrivillaga Over a year ago

@Dora Yeah, you can have as many optional parameters as you want. option1=(), option2=(),...

Dora Over a year ago

guess it was my system messed up, it was giving me errors doing it but after restarting it worked well. But if I have like more and more and more, is there a better way. I have been reading about **kwargs which seems helpful but somehow I couldn't get around to use it in this situation though

juanpa.arrivillaga Over a year ago

@Dora you could use **kwargs, but I would just stick with maybe *args. The only difference is the container for the variable number of arguments, the former gives you a dictionary of arguments, the latter a tuple of arguments. If you are just going to iterate over them in sequence and update some data structure, a tuple might be exactly what you need.

Max Power · Accepted Answer · 2017-04-14 23:50:06Z

0

def json_response_message(status, message, *args):

    #input validation
    assert len(args) == 0 or len(args) == 2

    # add required params to data
    data = {
    'status': status,
    'message': message,
    }

    # add optional params to data if provided
    if args:
      option_key = args[0]
      option_value = args[1]
      data[option_key] = option_value      

    return data

print(json_response_message(True, 'found', 'user', user))

{'user': 'jim', 'status': True, 'message': 'found'}

edited Apr 14, 2017 at 23:50

answered Apr 14, 2017 at 23:42

Max Power

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