You created a list of only the dictionary values, but then try to loop over it as if it already contains both keys and values of those dictionaries. Perhaps you wanted to loop over each matched dictionary?
l = [v for v in dictionary.values() if ":" in str(v)]
d = defaultdict(list)
for subdict in l:
for k, v in subdict.items():
I'd instead flatten the structure:
def flatten(dictionary):
for key, value in dictionary.iteritems():
if isinstance(value, dict):
# recurse
for res in flatten(value):
yield res
else:
yield key, value
then just search:
def GetKeyFromDictByValue(self, dictionary, value_to_find):
for key, value in flatten(dictionary):
if value == value_to_find:
return key
Demo:
>>> sample = {'a': {'a1': 'a2'}, "aa": "aa1", 'aaa': {'aaa1': 'aaa2'}}
>>> GetKeyFromDictByValue(None, sample, "a2")
'a1'