>>> import json
>>> data = "{'field1': 0, 'field2': 'hehehehe', 'field3': 'hahaha'}"
>>> json.loads(data)

Traceback (most recent call last): 
File “”, line 1, in 
File “/usr/lib/python3.5/json/init.py”, line 319, in loads 
return _default_decoder.decode(s) 
File “/usr/lib/python3.5/json/decoder.py”, line 339, in decode 
obj, end = self.raw_decode(s, idx=_w(s, 0).end()) 
File “/usr/lib/python3.5/json/decoder.py”, line 355, in raw_decode 
obj, end = self.scan_once(s, idx) 
json.decoder.JSONDecodeError: Expecting property name enclosed in double quotes: line 1 column 2 (char 1)

>>> data = json.dumps(eval(data))
>>> print(data)

{“field3”: “hahaha”, “field2”: “hehehehe”, “field1”: 0}

>>> print(json.loads(data))

{‘field3': ‘hahaha', ‘field2': ‘hehehehe', ‘field1': 0}