Initialize Project Structure

Begin by scaffolding a new Django project. Navigate to your desired workspace and run the following command:

django-admin startproject marketplace

To integrate MySQL as the database backend, ensure pymysql is configured in your project's __init__.py file:

import pymysql
pymysql.install_as_MySQLdb()

Database Configuration and Routing

In your settings.py, configure the primary and replica databases. This setup supports read/write splitting, where writes are directed to the primary instance and reads are offloaded to a replica.

DATABASES = {
    'default': {
        'ENGINE': 'django.db.backends.mysql',
        'NAME': 'marketplace_db',
        'USER': 'db_user',
        'PASSWORD': 'password',
        'HOST': '127.0.0.1',
        'PORT': '3306',
    },
    'replica': {
        'ENGINE': 'django.db.backends.mysql',
        'NAME': 'marketplace_db',
        'USER': 'db_user',
        'PASSWORD': 'password',
        'HOST': '127.0.0.1',
        'PORT': '3306',
    }
}

Create a router in utils/router.py to enforce these constraints:

class DataAccessRouter:
    def db_for_read(self, model, **hints):
        return 'replica'

    def db_for_write(self, model, **hints):
        return 'default'

    def allow_relation(self, obj1, obj2, **hints):
        return True

Register the router in settings.py:

DATABASE_ROUTERS = ['utils.router.DataAccessRouter']

Abstract Base Models

To standardize audit fields across the application, define an abstract base class. This avoids redundant code in your model definitions.

from django.db import models

class TimestampedModel(models.Model):
    created_at = models.DateTimeField(auto_now_add=True, verbose_name='Created Date')
    updated_at = models.DateTimeField(auto_now=True, verbose_name='Updated Date')

    class Meta:
        abstract = True

Modell Implementation

Organize your logic by creating dedicated apps: catalog, accounts, and orders. Configure a custom user model in settings.py by referencing the model class:

AUTH_USER_MODEL = 'accounts.User'

In accounts/models.py, extend the default user management:

from django.contrib.auth.models import AbstractUser
from utils.models import TimestampedModel

class User(AbstractUser, TimestampedModel):
    class Meta:
        db_table = 'app_users'

Schema Migration

Create the required database in MySQL, then synchronize your models with the data base schema using Django migration tools:

# In MySQL shell
CREATE DATABASE marketplace_db CHARACTER SET utf8mb4;

# In terminal
python manage.py makemigrations
python manage.py migrate