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15.5. What is JSON?

JSON stands for JavaScript Object Notation. It is a format for sharing data. You can read a JSON string from a file or from a URL and convert it into a Python dictionary or list. You can also convert a Python dictionary or list into a JSON string.

15.5.1. Converting a JSON String into a Python Object

In the following program, we use the built-in json library to parse the JSON string and return a Python list of dictionaries.

What do you think this code will print? Run it to see what it actually prints.

import json data = ''' [ { "id" : "001", "x" : "2", "name" : "Chuck" } , { "id" : "009", "x" : "7", "name" : "Brenda" } ]''' info = json.loads(data) print('User count:', len(info)) for item in info: print('Name', item['name']) print('Id', item['id']) print('Attribute', item['x'])

csp-10-2-2: Which method of the json library is used to convert a JSON string into a Python object?

Here is another example. Run the code to see what it does.

What do you think this code will print? Run it to see what it actually prints.

import json data = '''{"employees": [{"name": "Lena", "title": "sales person"}, {"name": "Paru", "title": "manager"}, {"name": "Tyra", "title": "vice president"}]}''' d1 = json.loads(data) people_list = d1["employees"] print(len(people_list)) for person in people_list: print(person.get('name'))

csp-10-2-4: What type of thing (class name) is data in the code above?

csp-10-2-5: What type of thing (class name) is d1 in the code above?

csp-10-2-6: Once you convert a JSON string to Python what are the two possible types for the Python object?

• dictionary and string
• Dictionaries are used in JSON, but strings only contain one element, so they are not as useful.
• dictionary and list
• JSON is constructed by nesting dictionaries and lists as needed.
• string and list
• Lists are used in JSON, but strings only contain one element, so they are not as useful.

15.5.2. Converting a Python object into a JSON string

You can also convert a Python list or dictionary to a JSON string.

What do you think this code will print? Run it to see what it actually prints.

import json d_list = [{'Year': 2022, 'First': 'Barb', 'Last': 'Ericson'}, {'Year': 2018, 'First': 'Mark', 'Last': 'Guzdial'}] print(json.dumps(d_list)) d = d_list[0] print(json.dumps(d))

csp-10-2-8: Which method of the json library is used to convert a Python object to a JSON string?

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