JSON is a syntax for storing and exchanging data.
JSON is text, written with JavaScript object notation.
JSON in Python
Python has a built-in package called json, which can be used to work with JSON data.
Example
Import the json module:
import json
Parse JSON – Convert from JSON to Python
If you have a JSON string, you can parse it by using the json.loads() method.
The result will be a Python dictionary.
Example
Convert from JSON to Python:import json
# some JSON:
x = ‘{ “name”:”John”, “age”:30, “city”:”New York”}’
# parse x:
y = json.loads(x)
# the result is a Python dictionary:
print(y[“age”])
Output:
30
Convert from Python to JSON
If you have a Python object, you can convert it into a JSON string by using the json.dumps() method.
Example
Convert from Python to JSON:import json
# a Python object (dict):
x = {
“name”: “John”,
“age”: 30,
“city”: “New York”
}
# convert into JSON:
y = json.dumps(x)
# the result is a JSON string:
print(y)
Output:
{“name”: “John”, “age”: 30, “city”: “New York”}
You can convert Python objects of the following types, into JSON strings:
- dict
- list
- tuple
- string
- int
- float
- True
- False
- None
Example
Convert Python objects into JSON strings, and print the values:import json
print(json.dumps({“name”: “John”, “age”: 30}))
print(json.dumps([“apple”, “bananas”]))
print(json.dumps((“apple”, “bananas”)))
print(json.dumps(“hello”))
print(json.dumps(42))
print(json.dumps(31.76))
print(json.dumps(True))
print(json.dumps(False))
print(json.dumps(None))
Output:
{“name”: “John”, “age”: 30}
[“apple”, “bananas”]
[“apple”, “bananas”]
“hello”
42
31.76
true
false
null
When you convert from Python to JSON, Python objects are converted into the JSON (JavaScript) equivalent:
| Python | JSON |
|---|---|
| dict | Object |
| list | Array |
| tuple | Array |
| str | String |
| int | Number |
| float | Number |
| True | true |
| False | false |
| None | null |
Example
Convert a Python object containing all the legal data types:import json
x = {
“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(x))
Output:
{“name”: “John”, “age”: 30, “married”: true, “divorced”: false, “children”: [“Ann”,”Billy”], “pets”: null, “cars”: [{“model”: “BMW 230”, “mpg”: 27.5}, {“model”: “Ford Edge”, “mpg”: 24.1}]}
Format the Result
The example above prints a JSON string, but it is not very easy to read, with no indentations and line breaks.
The json.dumps() method has parameters to make it easier to read the result:
Example
Use the indent parameter to define the numbers of indents:
import json
x = {
“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}
]
}
#use four indents to make it easier to read the result:
print(json.dumps(x, indent=4))
Output:
{
“name”: “John”,
“age”: 30,
“married”: true,
“divorced”: false,
“children”: [
“Ann”,
“Billy”
],
“pets”: null,
“cars”: [
{
“model”: “BMW 230”,
“mpg”: 27.5
},
{
“model”: “Ford Edge”,
“mpg”: 24.1
}
]
}
You can also define the separators, default value is (“, “, “: “), which means using a comma and a space to separate each object, and a colon and a space to separate keys from values:
Example
Use the separators parameter to change the default separator:
import json
x = {
“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}
]
}
#use . and a space to separate objects, and a space, a = and a space to separate keys from their values:
print(json.dumps(x, indent=4, separators=(“. “, ” = “)))
Output:
{
“name” = “John”.
“age” = 30.
“married” = true.
“divorced” = false.
“children” = [
“Ann”.
“Billy”
].
“pets” = null.
“cars” = [
{
“model” = “BMW 230”.
“mpg” = 27.5
}.
{
“model” = “Ford Edge”.
“mpg” = 24.1
}
]
}
Order the Result
The json.dumps() method has parameters to order the keys in the result:
Example
Use the sort_keys parameter to specify if the result should be sorted or not:
import json
x = {
“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}
]
}
#sort the result alphabetically by keys:
print(json.dumps(x, indent=4, sort_keys=True))
Output:
{
“age”: 30,
“cars”: [
{
“model”: “BMW 230”,
“mpg”: 27.5
},
{
“model”: “Ford Edge”,
“mpg”: 24.1
}
],
“children”: [
“Ann”,
“Billy”
],
“divorced”: false,
“married”: true,
“name”: “John”,
“pets”: null
}