Python Data Type Conversions: str ↔ list ↔ JSON and Common Transformations

1. str to list

1.1 Using ast.literal_eval

If the string represents a valid Python list, you can safely parse it with

import ast
str_list = "[1, 2, 3, 'hello', {'key': 'value'}]"
converted_list = ast.literal_eval(str_list)
print(converted_list)  # Output: [1, 2, 3, 'hello', {'key': 'value'}]

1.2 Using json.loads (for JSON‑formatted strings)

When the string follows JSON syntax,

import json
json_str = '[1, 2, 3, "hello", {"key": "value"}]'
converted_list = json.loads(json_str)
print(converted_list)  # Output: [1, 2, 3, "hello", {"key": "value"}]

2. str to json

2.1 Using json.loads

Parse a JSON‑style string into a Python object with

import json
json_str = '{"name": "Alice", "age": 25, "city": "New York"}'
converted_json = json.loads(json_str)
print(converted_json)  # Output: {'name': 'Alice', 'age': 25, 'city': 'New York'}

3. json to list

3.1 Using json.loads and extracting a list

Load a JSON array and treat it as a Python list:

import json
json_str = '[{"name": "Alice", "age": 25}, {"name": "Bob", "age": 30}]'
json_data = json.loads(json_str)
converted_list = json_data
print(converted_list)  # Output: [{'name': 'Alice', 'age': 25}, {'name': 'Bob', 'age': 30}]

4. list to json

4.1 Using json.dumps

Serialize a Python list to a JSON string:

import json
my_list = [1, 2, 3, "hello", {"key": "value"}]
json_str = json.dumps(my_list)
print(json_str)  # Output: [1, 2, 3, "hello", {"key": "value"}]

5. Other common conversions

5.1 dict to JSON string

import json
my_dict = {"name": "Alice", "age": 25, "city": "New York"}
json_str = json.dumps(my_dict)
print(json_str)  # Output: {"name": "Alice", "age": 25, "city": "New York"}

5.2 JSON string to dict

import json
json_str = '{"name": "Alice", "age": 25, "city": "New York"}'
converted_dict = json.loads(json_str)
print(converted_dict)  # Output: {'name': 'Alice', 'age': 25, 'city': 'New York'}

6. Example: Application in API automation

6.1 Receive response and convert to dict

import requests
import json
response = requests.get('https://api.example.com/data')
json_data = response.json()
print(json_data)  # Output: JSON object

6.2 Process JSON data

import json
json_str = '[{"name": "Alice", "age": 25}, {"name": "Bob", "age": 30}]'
json_data = json.loads(json_str)
names = [person['name'] for person in json_data]
print(names)  # Output: ['Alice', 'Bob']

7. Summary

We covered common Python data‑type conversion methods useful in interface automation testing: str→list (ast.literal_eval or json.loads), str→json (json.loads), json→list (json.loads with extraction), list→json (json.dumps), plus dictionary↔JSON string conversions.