Exercise: Convert User Record To JSON And Back¶

Requirement ¶

In Exercise: Refactoring - Extract Both CSV Formats Into Module, we created a set of routines around user records of the following form:

{
    'id': 2,    # int
    'firstname': 'Jörg',
    'lastname': 'Faschingbauer',
    'birth': '19.6.1966',
}

Preparing for MQTT communication (Exercise: MQTT: Publish User Records), it is advisable to create a module userdb_json.py that defines a transport format for transmission that is

Converted to before sending
Converted from after receiving

Usage is envisioned as follows:

import userdb_csv
import userdb_json

for user in userdb_csv.read_csv_noheader('some.csv'):   # could be ANY source, of course
    json_str = userdb_json.to_json(user)
    ... publish json_str to MQTT topic ...

Test Code ¶

The following test (see pytest Introduction, By Example for how to use it) can better express the requirement,

code/tests/test_user_json.py¶

import userdb_json


def test_user_to_json():
    user_sent = {
        'id': 1,
        'firstname': 'Jörg',
        'lastname': 'Faschingbauer',
        'birth': '19.6.1966',
    }

    json_user_sent = userdb_json.to_json(user_sent)
    user_received = userdb_json.from_json(json_user_sent)

    assert user_received['id'] == 1
    assert user_received['firstname'] == 'Jörg'
    assert user_received['lastname'] == 'Faschingbauer'
    assert user_received['birth'] == '19.6.1966'    