How I used a single DB instead of distributing data inside classes.

address.py

class Address:
    ''' An attempt to represent an address. '''

    def __init__(self, street, city, state, country):
        ''' Initialize main attributes. '''

        self.street  = street
        self.city    = city
        self.state   = state
        self.country = country

    def __str__(self):
        ''' Returns a nicely formatted address. '''
    
        lines = [self.street, self.city, self.state, self.country]
        return ', '.join(lines).title()

company.md

::: mermaid classDiagram

class Employee{
    +String         name
    +Int            id
    +IRole          role
    +IPayrollPolicy payroll_policy
    +Address        address
}

class IRole{
    +work()
}
<<interface>> IRole
Employee *-- IRole

class ManagerRole{
    +work()
}
ManagerRole --|> IRole

class DeveloperRole{
    +work()
}
DeveloperRole --|> IRole

class BackEndDeveloperRole{
    +work()
}
BackEndDeveloperRole --|> DeveloperRole

class FrontEndDeveloperRole{
    +work()
}
FrontEndDeveloperRole --|> DeveloperRole

class DesignerRole{
    +work()
}
DesignerRole --|> IRole

class SalespersonRole{
    +work()
}
SalespersonRole --|> IRole

class Address{
    +String street
    +String city
    +String state
    +String country
}
Employee *-- Address

class IPayrollPolicy{
    +Int payroll()
}
<<interface>> IPayrollPolicy
Employee *-- IPayrollPolicy

class SalaryPolicy{
    +Int salary
    +Int payroll()
}
SalaryPolicy --|> IPayrollPolicy

class CommissionPolicy{
    +Int commission_per_sale
    +Int sales_made
    +Int payroll()
}
CommissionPolicy --|> SalaryPolicy

class HourlyPolicy{
    +Int hour_rate
    +Int hours_worked
    +Int payroll()
}
HourlyPolicy --|> IPayrollPolicy

:::

company.py

from employees import employees

for employee in employees:
    print(employee)

print('Comments from the developer team:')
for employee in employees:
    try:
        print(f'- {employee.name} says: {employee.role.comment_on_coffee()}')
    except AttributeError:
        pass

db.json

[
    {
        "name"           : "Adam Smith",
        "id"             : 0,
        "role"           : "manager",
        "payroll_policy" : "salary",
        "monthly_salary" : 2000,
        "commission_rate": null,
        "sales_made"     : null,
        "hourly_rate"    : null,
        "hours_worked"   : null,
        "address"        : {
                            "street" : "The Smithies 840",
                            "city"   : "Smithtown",
                            "state"  : "North Virginia",
                            "country": "United States"
                           }
    },
    {
        "name"           : "Candelaria Candelarium",
        "id"             : 1,
        "role"           : "back_end_developer",
        "payroll_policy" : "salary",
        "monthly_salary" : 1000,
        "commission_rate": null,
        "sales_made"     : null,
        "hourly_rate"    : null,
        "hours_worked"   : null,
        "address"        : {
                            "street" : "Candles 1700",
                            "city"   : "Candum",
                            "state"  : "South Virginia",
                            "country": "United States"
                           }
    },
    {
        "name"           : "Jhon Ivi",
        "id"             : 2,
        "role"           : "front_end_developer",
        "payroll_policy" : "salary",
        "monthly_salary" : 1000,
        "commission_rate": null,
        "sales_made"     : null,
        "hourly_rate"    : null,
        "hours_worked"   : null,
        "address"        : {
                            "street" : "Candles 1700",
                            "city"   : "Candum",
                            "state"  : "South Virginia",
                            "country": "United States"
                           }
    },
    {
        "name"           : "Elon Misk",
        "id"             : 3,
        "role"           : "salesperson",
        "payroll_policy" : "commission",
        "monthly_salary" : 500,
        "commission_rate": 10,
        "sales_made"     : 5,
        "hourly_rate"    : null,
        "hours_worked"   : null,
        "address"        : {
                            "street" : "Miska Muska 2050",
                            "city"   : "Miskies",
                            "state"  : "Somwhere On",
                            "country": "Mars"
                           }
    },
    {
        "name"           : "Duane D'Lec",
        "id"             : 4,
        "role"           : "designer",
        "payroll_policy" : "hourly",
        "monthly_salary" : null,
        "commission_rate": null,
        "sales_made"     : null,
        "hourly_rate"    : 10,
        "hours_worked"   : 20,
        "address"        : {
                            "street" : "Dulce de Leche 177",
                            "city"   : "Dulces",
                            "state"  : "Buenos Aires",
                            "country": "Argentina"
                           }
    }
]

developer_comments.py

# This is not really a mixin, because since I use it just for DeveloperRole, it
# could perfectly be just a DeveloperRole's method. But I wanted to show how
# mixins can be used to add functionality to multiple classes.
# I'll have to find a better example for mixins inside this company...

class DeveloperCommentsMixin:
    ''' An attempt to represent typical developer comments. '''

    def comment_on_windows(self):
        ''' A comment we make on Windows. '''

        return 'Windows sucks!'

    def comment_on_coffee(self):
        ''' A comment we make on coffee. '''

        return 'No coffee, no code!'

employees.py

import json

from roles_system   import RolesSystem
from payroll_system import PayrollSystem
from address        import Address

class Employee:
    ''' An attempt to represent an employee. '''

    def __init__(self, **data):
        ''' Initialize main attributes. '''

        self.name           = data['name'].title()
        self.id             = data['id']
        self.role           = RolesSystem.get_role(data['role'])
        self.payroll_policy = PayrollSystem.get_policy(data['payroll_policy' ],
                                                       data['monthly_salary' ],
                                                       data['commission_rate'],
                                                       data['sales_made'     ],
                                                       data['hourly_rate'    ],
                                                       data['hours_worked'   ],)
        self.address        = Address(**data['address'])
    
    def __str__(self):
        ''' Returns a string that represents this employee. '''

        return(f'\nName: {self.name}\n'
               f'ID  : {self.id}\n'
               f'Works {self.role.work()}.\n'
               f'Getting paid ${self.payroll_policy.payroll} USD this month.\n'
               f'Lives at {self.address}.\n')

with open('db.json', 'r') as f:
    db = json.load(f)

employees = []
for employee in db:
    employees.append(Employee(**employee))

payroll_system.py

from developer_comments import DeveloperCommentsMixin

class RolesSystem:
    ''' An attempt to represent a roles system. '''
    
    @staticmethod
    def get_role(role):
        ''' Gets the role object. '''
    
        if role == 'manager':
            return ManagerRole()
        elif role == 'developer':
            return DeveloperRole()
        elif role == 'back_end_developer':
            return BackEndDeveloperRole()
        elif role == 'front_end_developer':
            return FrontEndDeveloperRole()
        elif role == 'salesperson':
            return SalespersonRole()
        elif role == 'designer':
            return DesignerRole()

class ManagerRole:
    ''' An attempt to represent a manager's role. '''

    def work(self):
        ''' Returns a string that represents this person working. '''

        return 'managing employees, setting goals, and reviewing results'

class DeveloperRole(DeveloperCommentsMixin):
    ''' An attempt to represent a developer's role. '''

    def work(self):
        ''' Returns a string that represents this person working. '''

        return("developing and enhancing continuously the company's digital "
                                                                      "systems")

class BackEndDeveloperRole(DeveloperRole):
    ''' An attempt to represent a back-end developer's role. '''

    def work(self):
        ''' Returns a string that represents this person working. '''

        return("developing and enhancing continuously the company's back-end")

class FrontEndDeveloperRole(DeveloperRole):
    ''' An attempt to represent a front-end developer's role. '''

    def work(self):
        ''' Returns a string that represents this person working. '''

        return("developing and enhancing continuously the company's front-end")

class SalespersonRole:
    ''' An attempt to represent a salesperson's role. '''

    def work(self):
        ''' Returns a string that represents this person working. '''

        return "making people buy the company's products and/or services"

class DesignerRole:
    ''' An attempt to represent a designer's role. '''

    def work(self):
        ''' Returns a string that represents this person working. '''

        return 'making this company beautiful'

roles_system.py

from developer_comments import DeveloperCommentsMixin

class RolesSystem:
    ''' An attempt to represent a roles system. '''
    
    @staticmethod
    def get_role(role):
        ''' Gets the role object. '''
    
        if role == 'manager':
            return ManagerRole()
        elif role == 'developer':
            return DeveloperRole()
        elif role == 'back_end_developer':
            return BackEndDeveloperRole()
        elif role == 'front_end_developer':
            return FrontEndDeveloperRole()
        elif role == 'salesperson':
            return SalespersonRole()
        elif role == 'designer':
            return DesignerRole()

class ManagerRole:
    ''' An attempt to represent a manager's role. '''

    def work(self):
        ''' Returns a string that represents this person working. '''

        return 'managing employees, setting goals, and reviewing results'

class DeveloperRole(DeveloperCommentsMixin):
    ''' An attempt to represent a developer's role. '''

    def work(self):
        ''' Returns a string that represents this person working. '''

        return("developing and enhancing continuously the company's digital "
                                                                      "systems")

class BackEndDeveloperRole(DeveloperRole):
    ''' An attempt to represent a back-end developer's role. '''

    def work(self):
        ''' Returns a string that represents this person working. '''

        return("developing and enhancing continuously the company's back-end")

class FrontEndDeveloperRole(DeveloperRole):
    ''' An attempt to represent a front-end developer's role. '''

    def work(self):
        ''' Returns a string that represents this person working. '''

        return("developing and enhancing continuously the company's front-end")

class SalespersonRole:
    ''' An attempt to represent a salesperson's role. '''

    def work(self):
        ''' Returns a string that represents this person working. '''

        return "making people buy the company's products and/or services"

class DesignerRole:
    ''' An attempt to represent a designer's role. '''

    def work(self):
        ''' Returns a string that represents this person working. '''

        return 'making this company beautiful'