Database Architecture¶

The application uses PostgreSQL with Django ORM.

Core Models¶

Product Hierarchy¶

erDiagram
    Category ||--o{ Product : contains
    Product ||--o{ ProductVariant : has
    Product ||--o{ ProductColorImage : has
    ProductVariant }o--|| Color : uses
    ProductVariant }o--|| Size : uses
    ProductColorImage }o--|| Color : uses

Order Flow¶

erDiagram
    User ||--o{ Order : places
    User ||--o{ ShoppingCart : has
    ShoppingCart ||--o{ CartItem : contains
    Order ||--o{ OrderItem : contains
    OrderItem }o--|| ProductVariant : references
    OrderItem }o--o| CustomDesign : includes

Key Models¶

Product¶

class Product(models.Model):
    name = models.CharField(max_length=200)
    slug = models.SlugField(unique=True)
    category = models.ForeignKey(Category, on_delete=models.PROTECT)
    base_price = models.DecimalField(max_digits=10, decimal_places=2)
    is_active = models.BooleanField(default=True)
    # Print area configuration
    max_print_width = models.IntegerField()
    max_print_height = models.IntegerField()

ProductVariant¶

class ProductVariant(models.Model):
    product = models.ForeignKey(Product, related_name='variants')
    color = models.ForeignKey(Color, on_delete=models.PROTECT)
    size = models.ForeignKey(Size, on_delete=models.PROTECT)
    sku = models.CharField(max_length=50, unique=True)
    stock_quantity = models.IntegerField(default=0)
    price_adjustment = models.DecimalField(default=0)

CustomDesign¶

class CustomDesign(models.Model):
    user = models.ForeignKey(User, null=True, on_delete=models.SET_NULL)
    product = models.ForeignKey(Product, on_delete=models.CASCADE)
    color = models.ForeignKey(Color, on_delete=models.PROTECT)
    # Fabric.js JSON data per view
    design_data_front = models.JSONField(null=True)
    design_data_back = models.JSONField(null=True)
    # Preview images
    preview_image_front = models.ImageField(null=True)
    preview_image_back = models.ImageField(null=True)

Database Indexes¶

Key indexes for performance:

class Meta:
    indexes = [
        models.Index(fields=['slug']),
        models.Index(fields=['is_active', 'category']),
        models.Index(fields=['sku']),
    ]

Migrations¶

Always review migrations before applying:

# Create migrations
python manage.py makemigrations --dry-run

# Review SQL
python manage.py sqlmigrate app_name 0001

# Apply migrations
python manage.py migrate