The setattr and getattr functions

See also hasattr.

"""
json2object.py

Convert a string that looks like a dictionary into a Python object
with attributes.
"""

import sys
import json                #JavaScript Object Notation

#Assume we have downloaded this JSON-format string from a server.

s = """\
{
   "name": "Mark",
   "age": 64,
   "favorite years": [1965, 1982, 1995],
   "IKEA language": {"Billy": "bookcase", "Sladda": "bike", "Klippan": "sofa"}
}"""

#Convert the string of characters into a dictionary.

try:
    dictionary = json.loads(s)
except json.JSONDecodeError as error:
    print(error)
    sys.exit(1)

#Copy the keys and values of the dictionary into a Python object of class Person.

class Person(object):
    pass

person = Person()   #Create an object of type Person.

for key, value in dictionary.items():
    setattr(person, key, value)

#Print the Python object to make sure it's okay.

for key in person.__dict__:
    print(key, getattr(person, key))

sys.exit(0)

name Mark
age 64
favorite years [1965, 1982, 1995]
IKEA language {'Billy': 'bookcase', 'Sladda': 'bike', 'Klippan': 'sofa'}

Note that at the end of the program we could have said

print(person.name)

print(person.favorite years)

Things to try

1. Does the object person have any methods? We will discover that person has many methods, inherited form the base class object. In the following code, attributes is a list of strings containing the names of all the attributes of person. Some of these attributes are variables and some are methods. methods is a list of strings containing the names of the attributes that are methods.

   attributes = dir(person)
   
   methods = [attribute for attribute in attributes
       if callable(getattr(person, attribute))]   #also try if not callable
   
   for i, method in enumerate(methods, start = 1):
       print(f"{i:2} {method}")
   

    1 __class__
    2 __delattr__
    3 __dir__
    4 __eq__
    5 __format__
    6 __ge__
    7 __getattribute__
    8 __gt__
    9 __hash__
   10 __init__
   11 __init_subclass__
   12 __le__
   13 __lt__
   14 __ne__
   15 __new__
   16 __reduce__
   17 __reduce_ex__
   18 __repr__
   19 __setattr__
   20 __sizeof__
   21 __str__
   22 __subclasshook__