UPDATE

With Python3, you can do it in one line, using SimpleNamespace and object_hook:

import json
from types import SimpleNamespace

data = '{"name": "John Smith", "hometown": {"name": "New York", "id": 123}}'

# Parse JSON into an object with attributes corresponding to dict keys.
x = json.loads(data, object_hook=lambda d: SimpleNamespace(**d))
# Or, in Python 3.13+:
#   json.loads(data, object_hook=SimpleNamespace)
print(x.name, x.hometown.name, x.hometown.id)

OLD ANSWER (Python2)

In Python2, you can do it in one line, using namedtuple and object_hook (but it's very slow with many nested objects):

import json
from collections import namedtuple

data = '{"name": "John Smith", "hometown": {"name": "New York", "id": 123}}'

# Parse JSON into an object with attributes corresponding to dict keys.
x = json.loads(data, object_hook=lambda d: namedtuple('X', d.keys())(*d.values()))
print x.name, x.hometown.name, x.hometown.id

or, to reuse this easily:

def _json_object_hook(d): return namedtuple('X', d.keys())(*d.values())
def json2obj(data): return json.loads(data, object_hook=_json_object_hook)

x = json2obj(data)

If you want it to handle keys that aren't good attribute names, check out namedtuple's rename parameter.

You have a JSON Lines format text file. You need to parse your file line by line:

import json

data = []
with open('file') as f:
    for line in f:
        data.append(json.loads(line))

Each line contains valid JSON, but as a whole, it is not a valid JSON value as there is no top-level list or object definition.

Note that because the file contains JSON per line, you are saved the headaches of trying to parse it all in one go or to figure out a streaming JSON parser. You can now opt to process each line separately before moving on to the next, saving memory in the process. You probably don't want to append each result to one list and then process everything if your file is really big.

If you have a file containing individual JSON objects with delimiters in-between, use How do I use the 'json' module to read in one JSON object at a time? to parse out individual objects using a buffered method.