how to deserialize JSON with keys that are not valid Python names in marshmallow

Question

I'm getting a JSON object with a key "sera:blah"

How would I deserialize that object into a python data type using the marshmallow library as that colon is an invalid property name?

Edit:

So classes in python cannot accept a colon in the porperty name. It's invalid syntax.

Edit2:

Ideally I would like to have a workaround within marshmallow.

Answer 1

I see 2 routes you can take with this

• Try to deserialize it with JSON.loads first, and iterate through each property and replace all the malformed keys before feeding it to marshmallow, or
• Use the JSON.JSONDecoder class and roll your own object_hook function. Then call the .decode() function before feeding it to marshmallow.

I've expanded on the latter (which I think is more appropriate)

from json import loads, JSONDecoder
s = """{
  "obj1": 123,
  "list": [
    {"example2": 42},
    {"sera:blah": false},
    {"object:3": {"nest:ed": "obj"}}
  ]
}"""

data = loads(s)
print(data)

def obj_transform(obj):
  for key in obj.keys():  # Iterate through obj
    if ':' in key:
      obj[key.replace(':', '_')] = obj.pop(key)
  return obj

decoder = JSONDecoder(object_hook=obj_transform)
print(decoder.decode(s))

The result of this prints:

{'obj1': 123, 'list': [{'example2': 42}, {'sera:blah': False}, {'object:3': {'nest:ed': 'obj'}}]}
{'obj1': 123, 'list': [{'example2': 42}, {'sera_blah': False}, {'object_3': {'nest_ed': 'obj'}}]}

Which seems like what you are looking for, to sanitize your input to marshmallow.