Testing various dict wrappers for Python JSON

python-json-types.py

"""
Various options for a JSON type for Python.
My best effort at using these libraries naturally for reading and writing JSON.

https://nelsonslog.wordpress.com/2016/01/08/a-better-python-object-for-json/
"""


import json, copy
import dotmap, attrdict, easydict, addict

sourceData = {
  "num": 3.4,
  "str": "foo",
  "list": [ 0, 1, 2, 3 ],
  "obj": {
    "num": 3.4,
    "str": "foo",
    "list": [ 0, 1, 2, 3 ]
  },
  "nested": { "several": { "levels" : { "deep": 5 } } } }

with open('test.json', 'w') as fp:
    json.dump(sourceData, fp)


loadedData = json.load(open('test.json'))

def usingDict(d):
    # Plain old Python dict requires [] syntax for reading
    assert d["num"]
    assert d["list"][1]
    assert d["nested"]["several"]["levels"]["deep"]

    # Missing elements throw exceptions with the [] operator, so use get
    assert d.get("noObj", {}) == {}
    assert d.get("noNum", 1)
    assert d.get("noList", []) == []

    # Adding nested elements requires either setdefault() or else several lines
    d["new"] = 5
    d["other"] = {}
    d["other"]["nested"] = {}
    d["other"]["nested"]["thing"] = 6

    # Serialization is easy of course
    return json.dumps(d)

def usingDotMap(d):
    # dotmap lets us use . syntax for reading
    d = dotmap.DotMap(d)
    assert d.num
    assert d.list[1]
    assert d.nested.several.levels.deep

    # Accessing a missing element with . creates an empty DotMap()
    assert d.noObj == {}
    assert d.get("noNum", 1)
    assert d.get("noList", []) == []

    # Creating new elements is really easy, even nested
    d.new = 5
    d.other.nested.thing = 6

    # Have to turn the DotMap into a dict to JSON encode it
    # Note we created a new property d.missing, value is {}
    return json.dumps(d.toDict())

def usingAttrDefault(d):
    # Create an attrdict where missing keys default to the value None
    d = attrdict.AttrDefault(lambda: None, d)

    # AttrDict lets us use . syntax for reading
    assert d.num
    assert d.list[1]
    assert d.nested.several.levels.deep

    # Missing attributes are none. Note: no way to override the default with get()
    assert d.noObj == None  # bummer!
    assert d.noNum == None
    assert d.get("noList", []) == None    # bummer!

    # No shortcut for nested objects, have to create them all
    d.new = 5
    d.other = {}
    d.other.nested = {}
    d.other.nested.thing = 6

    # No way to JSON serialize an AttrDefault?!
    try: return json.dumps(d)
    except: return ""

def usingAttrDict(d):
    # Create an attrdict with no default for missing keys
    d = attrdict.AttrDict(d)

    # AttrDict lets us use . syntax for reading
    assert d.num
    assert d.list[1]
    assert d.nested.several.levels.deep

    # We're on our own to handle missing attributes
    assert d.get("noObj", {}) == {}
    assert d.get("noNum", 1)
    assert d.get("noList", []) == []

    # Can't use dot syntax: "Recursive attribute access results in a shallow copy"
    d.new = 5
    d["other"] = {}
    d["other"]["nested"] = {}
    d["other"]["nested"]["thing"] = 6

    # AttrDict is a dict, so serializing is easy
    return json.dumps(d)

def usingEasyDict(d):
    # Create the easy dict
    d = easydict.EasyDict(d)

    # . syntax for reading
    assert d.num
    assert d.list[1]
    assert d.nested.several.levels.deep

    # Missing elements throw exceptions with both . and [] syntax, fall back to get()
    assert d.get("noObj", {}) == {}
    assert d.get("noNum", 1)
    assert d.get("noList", []) == []

    # Adding nested elements requires multiple lines
    d.new = 5
    d.other = {}
    d.other.nested = {}
    d.other.nested.thing = 6

    # EasyDict is a dict, so serializing is easy
    return json.dumps(d)

def usingAddict(d):
    d = addict.Dict(d)

    # . syntax for reading
    assert d.num
    assert d.list[1]
    assert d.nested.several.levels.deep

    # Missing elements create empty addict.Dict()s
    assert d.noObj == {}
    assert d.get("noNum", 1)
    assert d.get("noList", []) == []

    # Adding nested elements is a snap
    d.new = 5
    d.other.nested.thing = 6

    # addict.Dict is a dict, so can just serialize it.
    # we call prune first to clean out the d.noObj we created above
    d.prune()
    return json.dumps(d)

for f in (usingDict, usingDotMap, usingAttrDefault, usingAttrDict, usingEasyDict, usingAddict):
    d = copy.deepcopy(loadedData)
    r = f(d)
    print ("%-16s %4d" % (f.__name__, len(r)))