Python for beginners in Tieto Czech: JSON

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JSON

In Python, the json module provides an API similar to convert in-memory Python objects to a serialized representation known as JavaScript Object Notation (JSON) and vice-a-versa.

Encode Python objects as JSON strings

json.dump(obj, fp,
                  skipkeys=False,
                  ensure_ascii=True,
          check_circular=True,
          allow_nan=True,
          cls=None,
          indent=None,
          separators=None,
          default=None,
          sort_keys=False, **kw)

The above method serialize obj as a JSON formatted stream to fp (a .write()-supporting file-like object) using the following conversion table.

Python                                          JSON
dict                                            object
list, tuple                                     array
str                                             string
int, float, int- & float-derived Enums          number
True                                            true
False                                           false
None                                            null

Python Dictionaries to JSON strings

import json
student = {"101":{"class":'V', "Name":'Rohit',  "Roll_no":7},
           "102":{"class":'V', "Name":'David',  "Roll_no":8},
           "103":{"class":'V', "Name":'Samiya', "Roll_no":12}}
print(json.dumps(student));

Output:

{"103": {"class": "V", "Name": "Samiya", "Roll_no": 12}, 
"102": {"class": "V", "Name": "David", "Roll_no": 8}, 
"101": {"class": "V", "Name": "Rohit", "Roll_no": 7}}

Python Dictionaries to JSON strings (sorted by key)

import json
student = {"101":{"class":'V', "Name":'Rohit',  "Roll_no":7},
           "102":{"class":'V', "Name":'David',  "Roll_no":8},
           "103":{"class":'V', "Name":'Samiya', "Roll_no":12}}
print(json.dumps(student, sort_keys=True));

Ooutput:

{"101": {"Name": "Rohit", "Roll_no": 7, "class": "V"}, 
"102": {"Name": "David", "Roll_no": 8, "class": "V"}, 
"103": {"Name": "Samiya", "Roll_no": 12, "class": "V"}}

Python tuple to JSON array

import json
tup1 = 'Red', 'Black', 'White';
print(json.dumps(tup1));

Output:

["Red", "Black", "White"]

Python list to JSON array

import json
list1 = [5, 12, 13, 14];
print(json.dumps(list1));

Output:

[5, 12, 13, 14]

Python string to JSON string

import json
string1 = 'Python and JSON';
print(json.dumps(string1));

Output:

"Python and JSON"

Python int, float, int- & float-derived Enums to JSON number

import json
x = -456;
y = -1.406;
z =  2.12e-10
print(json.dumps(x));
print(json.dumps(y));
print(json.dumps(z));

Output:

-456
-1.406
2.12e-10

Decode JSON strings into Python objects

Basic usage:

json.load(fp, 
          cls=None, 
          object_hook=None, 
          parse_float=None, 
          parse_int=None, 
          parse_constant=None, 
          object_pairs_hook=None, **kw)

JSON                Python
object              dict
array               list
string              str
number (int)        int
number (real)       float
true                True
false               False
null                None

JSON strings to Python Dictionaries

import json
json_data = '{"103": {"class": "V", "Name": "Samiya", "Roll_n": 12}, "102": {"class": "V", "Name": "David", "Roll_no": 8}, "101": {"class": "V", "Name": "Rohit", "Roll_no": 7}}';
print(json.loads(json_data));

Output:

{"103": {"class": "V", "Name": "Samiya", "Roll_no": 12}, 
"102": {"class": "V", "Name": "David", "Roll_no": 8}, 
"101": {"class": "V", "Name": "Rohit", "Roll_no": 7}}

Python list to JSON array

import json
list1 = '[ "Ford", "BMW", "Fiat" ]'
print(json.loads(list1));

JSON string to Python string

import json 
Json_string = "Python and JSON" 
print(json.dumps(Json_string));

Output:

"Python and JSON"

Toto je stránka lekce z kurzu, který probíhá nebo proběhl naživo s instruktorem.

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