I am new to Python and I am playing with JSON data. I would like to dynamically build a JSON object by adding some key-value to an existing JSON object.
I tried the following but I get TypeError: 'str' object does not support item assignment:
import json
json_data = json.dumps({})
json_data["key"] = "value"
print 'JSON: ', json_data
You build the object before encoding it to a JSON string:
import json
data = {}
data['key'] = 'value'
json_data = json.dumps(data)
JSON is a serialization format, textual data representing a structure. It is not, itself, that structure.
json_data['key'] = 'value', which won't work because json_data is not a Python dictionary.
pip list gives you the same information and can output JSON: pip list --format=jsonYou can create the Python dictionary and serialize it to JSON in one line and it's not even ugly.
my_json_string = json.dumps({'key1': val1, 'key2': val2})
There is already a solution provided which allows building a dictionary, (or nested dictionary for more complex data), but if you wish to build an object, then perhaps try 'ObjDict'. This gives much more control over the json to be created, for example retaining order, and allows building as an object which may be a preferred representation of your concept.
pip install objdict first.
from objdict import ObjDict
data = ObjDict()
data.key = 'value'
json_data = data.dumps()
json.dumps i.e. json.dumps(response, sort_keys=True, indent=4), but then you're stuck with alphabetical order and not your preferred ordering, grouping and representation
json.loads take a string as input and returns a dictionary as output.json.dumps take a dictionary as input and returns a string as output.If you need to convert JSON data into a python object, it can do so with Python3, in one line without additional installations, using SimpleNamespace and object_hook:
import json
from types import SimpleNamespace
string = '{"foo":3, "bar":{"x":1, "y":2}}'
# Parse JSON into an object with attributes corresponding to dict keys.
x = json.loads(string, object_hook=lambda d: SimpleNamespace(**d))
print(x.foo)
print(x.bar.x)
print(x.bar.y)
output:
3
1
2
JSON object: data.json
{
"foo": 3,
"bar": {
"x": 1,
"y": 2
}
}
import json
from types import SimpleNamespace
with open("data.json") as fh:
string = fh.read()
# Parse JSON into an object with attributes corresponding to dict keys.
x = json.loads(string, object_hook=lambda d: SimpleNamespace(**d))
print(x.foo)
print(x.bar.x)
print(x.bar.y)
output:
3
1
2
import json
from types import SimpleNamespace
import requests
r = requests.get('https://api.github.com/users/MilovanTomasevic')
# Parse JSON into an object with attributes corresponding to dict keys.
x = json.loads(r.text, object_hook=lambda d: SimpleNamespace(**d))
print(x.name)
print(x.company)
print(x.blog)
output:
Milovan Tomašević
NLB
milovantomasevic.com
For more beautiful and faster access to JSON response from API, take a look at this response.
All previous answers are correct, here is one more and easy way to do it. For example, create a Dict data structure to serialize and deserialize an object
(Notice None is Null in python and I'm intentionally using this to demonstrate how you can store null and convert it to json null)
import json
print('serialization')
myDictObj = { "name":"John", "age":30, "car":None }
##convert object to json
serialized= json.dumps(myDictObj, sort_keys=True, indent=3)
print(serialized)
## now we are gonna convert json to object
deserialization=json.loads(serialized)
print(deserialization)
EasyDict library (doc):EasyDict allows to access dict values as attributes (works recursively). A Javascript-like properties dot notation for python dicts.
USEAGE
>>> from easydict import EasyDict as edict >>> d = edict({'foo':3, 'bar':{'x':1, 'y':2}}) >>> d.foo 3 >>> d.bar.x 1 >>> d = edict(foo=3) >>> d.foo 3
[INSTALLATION]:
pip install easydict
I create a recursive function to walk a nest dictionary representing the json structure.
myjson={}
myjson["Country"]= {"KR": { "id": "220", "name": "South Korea"}}
myjson["Creative"]= {
"1067405": {
"id": "1067405",
"url": "https://cdn.gowadogo.com/559d1ba1-8d50-4c7f-b3f5-d80f918006e0.jpg"
},
"1067406": {
"id": "1067406",
"url": "https://cdn.gowadogo.com/3799a70d-339c-4ecb-bc1f-a959dde675b8.jpg"
},
"1067407": {
"id": "1067407",
"url": "https://cdn.gowadogo.com/180af6a5-251d-4aa9-9cd9-51b2fc77d0c6.jpg"
}
}
myjson["Offer"]= {
"advanced_targeting_enabled": "f",
"category_name": "E-commerce/ Shopping",
"click_lifespan": "168",
"conversion_cap": "50",
"currency": "USD",
"default_payout": "1.5"
}
json_data = json.dumps(myjson)
#reverse back into a json
paths=[]
def walk_the_tree(inputDict,suffix=None):
for key, value in inputDict.items():
if isinstance(value, dict):
if suffix==None:
suffix=key
else:
suffix+=":"+key
walk_the_tree(value,suffix)
else:
paths.append(suffix+":"+key+":"+value)
walk_the_tree(myjson)
print(paths)
#split and build your nested dictionary
json_specs = {}
for path in paths:
parts=path.split(':')
value=(parts[-1])
d=json_specs
for p in parts[:-1]:
if p==parts[-2]:
d = d.setdefault(p,value)
else:
d = d.setdefault(p,{})
print(json_specs)
Paths:
['Country:KR:id:220', 'Country:KR:name:South Korea', 'Country:Creative:1067405:id:1067405', 'Country:Creative:1067405:url:https://cdn.gowadogo.com/559d1ba1-8d50-4c7f-b3f5-d80f918006e0.jpg', 'Country:Creative:1067405:1067406:id:1067406', 'Country:Creative:1067405:1067406:url:https://cdn.gowadogo.com/3799a70d-339c-4ecb-bc1f-a959dde675b8.jpg', 'Country:Creative:1067405:1067406:1067407:id:1067407', 'Country:Creative:1067405:1067406:1067407:url:https://cdn.gowadogo.com/180af6a5-251d-4aa9-9cd9-51b2fc77d0c6.jpg', 'Country:Creative:Offer:advanced_targeting_enabled:f', 'Country:Creative:Offer:category_name:E-commerce/ Shopping', 'Country:Creative:Offer:click_lifespan:168', 'Country:Creative:Offer:conversion_cap:50', 'Country:Creative:Offer:currency:USD', 'Country:Creative:Offer:default_payout:1.5']
You can create a JSON file by using the jsonCreator module
jsonCreator.createJson(dict, "fileName", ["path"])
