from django.apps import apps import random import string from datetime import timedelta from uuid import uuid4 from imagekit.models import ProcessedImageField from imagekit.processors import ResizeToFill from django.db import models from django.core.exceptions import ValidationError from django.utils.text import slugify from django.utils.timezone import now from suppliers.models import Supplier # Import Supplier from the suppliers app # Custom manager for handling soft-deleted records class ActiveManager(models.Manager): def get_queryset(self): return super().get_queryset().filter(deleted_at__isnull=True) # Category model class Category(models.Model): name = models.CharField(max_length=255, unique=True) slug = models.SlugField(unique=True, max_length=255, blank=True, null=True) description = models.TextField(blank=True, null=True) thumbnail = models.ImageField(upload_to='category_images/', blank=True, null=True) parent = models.ForeignKey('self', null=True, blank=True, related_name='subcategories', on_delete=models.CASCADE) deleted_at = models.DateTimeField(null=True, blank=True) def save(self, *args, **kwargs): if not self.slug: self.slug = slugify(self.name) super().save(*args, **kwargs) def __str__(self): return self.name # Product model class Product(models.Model): name = models.CharField(max_length=255) variant = models.CharField(max_length=255, blank=True, null=True) # For variants like size or color slug = models.SlugField(unique=True, max_length=255) # SEO-friendly unique URL barcode = models.CharField(max_length=255, blank=True, null=True, unique=True, db_index=True) buying_price = models.DecimalField(max_digits=10, decimal_places=2, blank=True, null=True) selling_price = models.DecimalField(max_digits=10, decimal_places=2) wholesale_price = models.DecimalField(max_digits=10, decimal_places=2, blank=True, null=True) stock_quantity = models.PositiveIntegerField(default=0) low_stock_threshold = models.PositiveIntegerField(default=0) packaging_type = models.CharField(max_length=50, blank=True, null=True) # E.g., "Box", "Bottle" expiry_date = models.DateField(blank=True, null=True) created_at = models.DateTimeField(auto_now_add=True) category = models.ForeignKey('Category', null=True, blank=True, on_delete=models.SET_NULL, db_index=True, related_name='products') description = models.TextField(blank=True, null=True) image = models.ImageField(upload_to='product_images/', blank=True, null=True) is_featured = models.BooleanField(default=False, db_index=True) discount_price = models.DecimalField(max_digits=10, decimal_places=2, blank=True, null=True) is_active = models.BooleanField(default=True, db_index=True) # Products are active by default deleted_at = models.DateTimeField(null=True, blank=True) # SEO metadata seo_title = models.CharField(max_length=70, blank=True, null=True) seo_description = models.TextField(blank=True, null=True) # Managers objects = ActiveManager() # Filters out soft-deleted records all_objects = models.Manager() # Includes all records, including soft-deleted ones def __str__(self): return f"{self.name} ({self.variant})" if self.variant else self.name def clean(self): """ Validation logic for product fields. """ if self.buying_price is not None and self.selling_price <= self.buying_price: raise ValidationError("Selling price must be greater than buying price.") if self.discount_price and self.discount_price >= self.selling_price: raise ValidationError("Discount price must be less than the selling price.") if self.stock_quantity < 0: raise ValidationError("Stock quantity cannot be negative.") if self.low_stock_threshold < 0: raise ValidationError("Low stock threshold cannot be negative.") def save(self, *args, **kwargs): """ Override save method to handle slug and barcode generation. """ if not self.slug: base_slug = slugify(f"{self.name}-{self.variant}" if self.variant else self.name) unique_slug = base_slug counter = 1 # Ensure unique slug while Product.objects.filter(slug=unique_slug).exists(): unique_slug = f"{base_slug}-{counter}" counter += 1 self.slug = unique_slug if not self.barcode: self.barcode = self.generate_barcode() self.clean() super().save(*args, **kwargs) @staticmethod def generate_barcode(): """ Generates a random 12-digit barcode. """ return ''.join(random.choices(string.digits, k=12)) def delete(self, *args, **kwargs): """ Soft-delete the product by setting `deleted_at` to the current timestamp. """ self.deleted_at = now() self.save() def restore(self): """ Restore a soft-deleted product by clearing the `deleted_at` field. """ self.deleted_at = None self.save() def is_low_stock(self): """ Check if the product stock is below the low stock threshold. """ return self.stock_quantity <= self.low_stock_threshold def is_nearing_expiry(self): """ Check if the product is nearing expiry within 30 days. """ if self.expiry_date: return now().date() >= (self.expiry_date - timedelta(days=30)) return False def has_expired(self): """ Check if the product has expired. """ if self.expiry_date: return now().date() > self.expiry_date return False class Meta: unique_together = ['name', 'variant'] # Ensure unique product-variant combinations # Product image model class ProductImage(models.Model): product = models.ForeignKey(Product, related_name='images', on_delete=models.CASCADE) image = ProcessedImageField( upload_to='product_images/', processors=[ResizeToFill(800, 800)], format='JPEG', options={'quality': 85}, ) thumbnail = ProcessedImageField( upload_to='product_thumbnails/', processors=[ResizeToFill(200, 200)], format='JPEG', options={'quality': 85}, blank=True, null=True, ) is_primary = models.BooleanField(default=False) alt_text = models.CharField(max_length=255, blank=True, null=True) order = models.PositiveIntegerField(default=0) caption = models.CharField(max_length=255, blank=True, null=True) def clean(self): if self.is_primary and self.product.images.filter(is_primary=True).exists(): raise ValidationError("Only one primary image is allowed per product.") def __str__(self): return f"Image for {self.product.name}" class Meta: ordering = ['order'] # Sort images by order field # Batch model class Batch(models.Model): STATUS_CHOICES = [ ('active', 'Active'), ('expired', 'Expired'), ('sold_out', 'Sold Out'), ] product = models.ForeignKey('Product', related_name='batches', on_delete=models.CASCADE) batch_code = models.CharField(max_length=255, blank=True, null=True) quantity = models.PositiveIntegerField() buying_price = models.DecimalField(max_digits=10, decimal_places=2) selling_price = models.DecimalField(max_digits=10, decimal_places=2, blank=True, null=True) expiry_date = models.DateField(blank=True, null=True) created_at = models.DateTimeField(auto_now_add=True) deleted_at = models.DateTimeField(null=True, blank=True) received_date = models.DateField(default=now) status = models.CharField(max_length=20, choices=STATUS_CHOICES, default='active') notes = models.TextField(blank=True, null=True) supplier = models.ForeignKey(Supplier, on_delete=models.SET_NULL, null=True, blank=True) objects = ActiveManager() # Exclude soft-deleted all_objects = models.Manager() # Include all records def clean(self): """ Validation logic to ensure data integrity. """ if self.expiry_date and self.expiry_date < now().date(): raise ValidationError("Expiry date cannot be in the past.") if self.quantity < 0: raise ValidationError("Batch quantity cannot be negative.") if self.selling_price and self.selling_price <= self.buying_price: raise ValidationError("Selling price must be greater than buying price.") def save(self, *args, **kwargs): """ Override save to generate batch code if not provided. """ if not self.batch_code: self.batch_code = self.generate_batch_code() # Dynamically load the Supplier model during save Supplier = apps.get_model('suppliers', 'Supplier') # Dynamically load Supplier model super().save(*args, **kwargs) @staticmethod def generate_batch_code(): """ Generates a unique batch code. """ return f"BATCH-{uuid4().hex[:6].upper()}" def __str__(self): return f"Batch {self.batch_code} for {self.product.name}" class Meta: ordering = ['received_date'] # Sort batches by received date