Python JSON Handling: Encoding, Decoding, File I/O, Pretty‑Printing, Sorting, Custom Types and Non‑ASCII Support

1. Encode a Python object to a JSON string – Use json.dumps to serialize a dictionary and print the resulting JSON text.

import json
data = {"name": "Alice", "age": 30, "is_student": False}
json_data = json.dumps(data)
print("JSON string:", json_data)

2. Decode a JSON string back to a Python object – Apply json.loads on a JSON‑formatted string and display the reconstructed dictionary.

import json
json_str = '{"name": "Alice", "age": 30, "is_student": false}'
data = json.loads(json_str)
print("Python object:", data)

3. Write a Python object to a JSON file – Open a file in write mode and use json.dump to store the data.

import json
data = {"name": "Alice", "age": 30, "is_student": False}
with open("data.json", "w") as f:
    json.dump(data, f)
print("Data saved to file")

4. Read a JSON file into a Python object – Open the file in read mode and load its contents with json.load .

import json
with open("data.json", "r") as f:
    data = json.load(f)
print("Read data:", data)

5. Pretty‑print JSON data – Use json.dumps with the indent parameter to format the output.

import json
data = {"name": "Alice", "age": 30, "is_student": False, "skills": ["Python", "JavaScript", "C++"]}
pretty_json = json.dumps(data, indent=4)
print("Pretty JSON output:\n", pretty_json)

6. Sort JSON output keys – Set sort_keys=True in json.dumps to produce an alphabetically ordered JSON string.

import json
data = {"name": "Alice", "age": 30, "is_student": False, "skills": ["Python", "JavaScript", "C++"]}
sorted_json = json.dumps(data, indent=4, sort_keys=True)
print("Sorted JSON output:\n", sorted_json)

7. Handle special types with a custom encoder – Subclass json.JSONEncoder to convert unsupported objects (e.g., set ) to JSON‑serializable forms.

import json
class MyEncoder(json.JSONEncoder):
    def default(self, obj):
        if isinstance(obj, set):
            return list(obj)
        return json.JSONEncoder.default(self, obj)

data = {"name": "Alice", "age": 30, "is_student": False, "skills": set(["Python", "JavaScript", "C++"])}
json_data = json.dumps(data, cls=MyEncoder)
print("JSON with special types:\n", json_data)

8. Preserve original key order – Use json.dumps with ensure_ascii=False (Python 3.7+ maintains insertion order by default).

import json
data = {"name": "Alice", "age": 30, "is_student": False, "skills": ["Python", "JavaScript", "C++"]}
json_data = json.dumps(data, indent=4, ensure_ascii=False)
print("Ordered JSON data:\n", json_data)

9. Serialize non‑ASCII characters – Set ensure_ascii=False to keep Unicode characters intact in the output.

import json
data = {"name": "Alice", "age": 30, "is_student": False, "skills": ["Python", "JavaScript", "C++"], "notes": "这是一个测试\n包含中文字符"}
json_data = json.dumps(data, indent=4, ensure_ascii=False)
print("JSON with non‑ASCII characters:\n", json_data)

10. Process binary JSON data – Decode a bytes object to a string, then use json.loads and json.dumps for conversion.

import json
binary_data = b'{"name": "Alice", "age": 30, "is_student": false}'
str_data = binary_data.decode('utf-8')
obj = json.loads(str_data)
print("Decoded Python object:", obj)
json_str = json.dumps(obj)
print("Re‑encoded JSON string:", json_str)