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Python - Json Library

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• Python - Json Library
  • JSON
  • json.loads(): String -> Dict
  • json.dumps(): Dict -> String

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JSON

• JSON is a syntax for storing and exchanging data.

• JSON is text, written with JavaScript object notation.

• json: a built-in package to work with JSON data.

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json.loads(): String -> Dict

• json.loads(): Convert from JSON String to Python Dictionary

print("\n----------json.loads()-------\n")
import json

json_str = '{ "name":"John", "age":30, "city":"New York"}'
json_dict = json.loads(json_str)

print(json_dict)                # {'name': 'John', 'age': 30, 'city': 'New York'}
print(json_dict["age"])         # 30

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json.dumps(): Dict -> String

• json.dumps(): convert a Python object into a JSON string

• parameter:

  • indent: number, define the numbers of indents.
  • separators: tuple, change the default separator. default separator is (“, “, “: “).
  • sort_keys: boolean, specify if the order of the keys should be sorted or not.

import json
print("\n----------json.dumps(): indent-------\n")

print(json.dumps({"name": "John", "age": 30}))
# {"name": "John", "age": 30}

print(json.dumps({"name": "John", "age": 30}, indent=2))
# {
#   "name": "John",
#   "age": 30
# }


print("\n----------json.dumps(): separators-------\n")

print(json.dumps({"name": "John", "age": 30}))
# {"name": "John", "age": 30}

print(json.dumps({"name": "John", "age": 30}, separators=(". ", " = ")))
# {"name" = "John". "age" = 30}


print("\n----------json.dumps(): sort_keys-------\n")

print(json.dumps({"name": "John", "age": 30}))
# {"name": "John", "age": 30}

print(json.dumps({"name": "John", "age": 30}, sort_keys=True))
# {"age": 30, "name": "John"}

• Different type of Python object convert to JSON.
  • Set cannot convert to JSON (not JSON serializable).

print("\n----------json.dumps()-------\n")
import json

xDict = {
  "name": "John",
  "age": 30,
  "married": True,
  "divorced": False,
  "children": ("Ann","Billy"),
  "pets": None,
  "cars": [
    {"model": "BMW 230", "mpg": 27.5},
    {"model": "Ford Edge", "mpg": 24.1}
  ]
}

print(json.dumps(xDict))


print("dict:\t\t", json.dumps({"name": "John", "age": 30}))     # dict:            {"name": "John", "age": 30}
print("list:\t\t", json.dumps(["apple", "bananas"]))            # list:            ["apple", "bananas"]
print("tuple:\t\t", json.dumps(("apple", "bananas")))           # tuple:           ["apple", "bananas"]
print("string:\t\t", json.dumps("hello"))                       # string:          "hello"
print("int:\t\t", json.dumps(42))                               # int:             42
print("float:\t\t", json.dumps(31.76))                          # float:           31.76
print("boolean:\t", json.dumps(True))                           # boolean:         true
print("boolean:\t", json.dumps(False))                          # boolean:         false
print("None:\t\t", json.dumps(None))                            # None:            null

# print(json.dumps({1,2,3}))      # TypeError: Object of type set is not JSON serializable

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