blue/green django

django.py

# models.py

from django.db import models

class User(models.Model):
    # Old field (blue version)
    name = models.CharField(max_length=100)
    
    # New fields (green version)
    first_name = models.CharField(max_length=50, null=True, blank=True)
    last_name = models.CharField(max_length=50, null=True, blank=True)
    
    email = models.EmailField(unique=True)

# migrations/0002_expand_user_model.py

from django.db import migrations, models

class Migration(migrations.Migration):
    dependencies = [
        ('yourapp', '0001_initial'),
    ]

    operations = [
        migrations.AddField(
            model_name='User',
            name='first_name',
            field=models.CharField(max_length=50, null=True, blank=True),
        ),
        migrations.AddField(
            model_name='User',
            name='last_name',
            field=models.CharField(max_length=50, null=True, blank=True),
        ),
    ]

# migrations/0003_populate_new_name_fields.py

from django.db import migrations

def split_name(apps, schema_editor):
    User = apps.get_model('yourapp', 'User')
    for user in User.objects.all():
        names = user.name.split(' ', 1)
        user.first_name = names[0]
        user.last_name = names[1] if len(names) > 1 else ''
        user.save()

class Migration(migrations.Migration):
    dependencies = [
        ('yourapp', '0002_expand_user_model'),
    ]

    operations = [
        migrations.RunPython(split_name),
    ]

# views.py

from django.conf import settings
from .models import User

def get_user_name(user):
    if settings.USE_NEW_NAME_FIELDS:
        return f"{user.first_name} {user.last_name}".strip()
    return user.name

def create_user(data):
    user = User(
        name=f"{data['first_name']} {data['last_name']}".strip(),
        email=data['email']
    )
    if settings.USE_NEW_NAME_FIELDS:
        user.first_name = data['first_name']
        user.last_name = data['last_name']
    user.save()
    return user

# settings.py

# Feature flag to control which version is active
USE_NEW_NAME_FIELDS = False  # Set to True for green environment

# Blue/Green deployment settings
BLUE_GREEN_DEPLOYMENT = True
DEPLOYMENT_COLOR = 'blue'  # Change to 'green' for green environment

# middleware.py

from django.conf import settings

class BlueGreenMiddleware:
    def __init__(self, get_response):
        self.get_response = get_response

    def __call__(self, request):
        if settings.BLUE_GREEN_DEPLOYMENT:
            request.session['deployment_color'] = settings.DEPLOYMENT_COLOR
        return self.get_response(request)

# wsgi_blue.py and wsgi_green.py

import os
from django.core.wsgi import get_wsgi_application

os.environ.setdefault('DJANGO_SETTINGS_MODULE', 'yourproject.settings')
os.environ['DEPLOYMENT_COLOR'] = 'blue'  # or 'green' for wsgi_green.py
application = get_wsgi_application()

# nginx.conf (example configuration)

upstream blue {
    server unix:/path/to/blue.sock;
}

upstream green {
    server unix:/path/to/green.sock;
}

server {
    listen 80;
    server_name yourdomain.com;

    location / {
        proxy_pass http://blue;  # Change to green when ready
    }
}

# migrations/0004_remove_name_field.py (Apply after full transition to green)

from django.db import migrations

class Migration(migrations.Migration):
    dependencies = [
        ('yourapp', '0003_populate_new_name_fields'),
    ]

    operations = [
        migrations.RemoveField(
            model_name='User',
            name='name',
        ),
    ]