Question

I’m looking for ways to write functions like get_profile(js) but without all the ugly try/excepts.

Each assignment is in a try/except because occasionally the json field doesn’t exist. I’d be happy with an elegant solution which defaulted everything to None even though I’m setting some defaults to [] and such, if doing so would make the overall code much nicer.

def get_profile(js):
    """ given a json object, return a dict of a subset of the data.
        what are some cleaner/terser ways to implement this?

        There will be many other get_foo(js), get_bar(js) functions which
        need to do the same general type of thing.
    """

    d = {}

    try:
        d['links'] = js['entry']['gd$feedLink']
    except:
        d['links'] = []

    try:
        d['statisitcs'] = js['entry']['yt$statistics']
    except:
        d['statistics'] = {}

    try:
        d['published'] = js['entry']['published']['$t']
    except:
        d['published'] = ''

    try:
        d['updated'] = js['entry']['updated']['$t']
    except:
        d['updated'] = ''

    try:
        d['age'] = js['entry']['yt$age']['$t']
    except:
        d['age'] = 0

    try:
        d['name'] = js['entry']['author'][0]['name']['$t']
    except:
        d['name'] = ''

    return d

Answer 1

Try something like…

import time

def get_profile(js):
    def cas(prev, el):
        if hasattr(prev, "get") and prev:
            return prev.get(el, prev)
        return prev
    def getget(default, *elements):
        return reduce(cas, elements[1:], js.get(elements[0], default))

    d = {}
    d['links'] = getget([], 'entry', 'gd$feedLink')
    d['statistics'] = getget({}, 'entry', 'yt$statistics')
    d['published'] = getget('', 'entry', 'published', '$t')
    d['updated'] = getget('', 'entry', 'updated', '$t')
    d['age'] = getget(0, 'entry', 'yt$age', '$t')
    d['name'] = getget('', 'entry', 'author', 0, 'name' '$t')
    return d

print get_profile({
    'entry':{
        'gd$feedLink':range(4),
        'yt$statistics':{'foo':1, 'bar':2},
        'published':{
            "$t":time.strftime("%x %X"),
        }, 
        'updated':{
            "$t":time.strftime("%x %X"),
        },
        'yt$age':{
            "$t":"infinity years",
        },
        'author':{0:{'name':{'$t':"I am a cow"}}},
    }
})

It’s kind of a leap of faith for me to assume that you’ve got a dictionary with a key of 0 instead of a list but… You get the idea.