python recursive dictionary converting to strings

Question

I had a problem on converting dictionaries to strings which has recursive features. I had a map of routing such as the following;

urls = {
    '/' : 'BaseController.hello',
    '/api' : {
        '/auth' : {
            '/me' : 'ApiController.hello',
            '/login' : {
                '/guest' : 'ApiController.guest_login',
                '/member': 'ApiController.member_login'
            }
        }
    }
}

What I need to do is to generate a dictionary from that into the following;

url_map = {
    '/' : 'BaseController.hello',
    '/api/auth/me' : 'ApiController.hello',
    '/api/auth/login/guest' : 'ApiController.guest_login',
    '/api/auth/login/member': 'ApiController.member_login',
}

This feature is called route grouping but I haven't been able to write a function to generate that. Any ideas ?

I haven't been able to write a function,- show your attempts then. — vaultah
– vaultah, Commented Jul 23, 2014 at 13:19

wwii · Accepted Answer · 2014-07-23 14:26:37Z

4

You can recursively do it like this

def flatten(current_dict, current_key, result_dict):

    # For every key in the dictionary
    for key in current_dict:
        # If the value is of type `dict`, then recurse with the value
        if isinstance(current_dict[key], dict):
            flatten(current_dict[key], current_key + key, result_dict)
        # Otherwise, add the element to the result
        else:
            result_dict[current_key + key] = current_dict[key]
    return result_dict

print flatten(urls, "", {})

Output

{
    '/api/auth/me': 'ApiController.hello',
    '/api/auth/login/guest': 'ApiController.guest_login',
    '/': 'BaseController.hello',
    '/api/auth/login/member': 'ApiController.member_login'
}

edited Jul 23, 2014 at 14:26

wwii

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answered Jul 23, 2014 at 13:24

thefourtheye

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2 Comments

wwii Over a year ago

I would have thought that you would have to pass result_dict in the recursive call - does this work because dict is a mutable default argument?

thefourtheye Over a year ago

@wwii It works because the default parameters are evaluated only when the function is defined, not when it is invoked.

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