Weight-Based Products

Selling Products by Weight with EAN-13 Barcodes

Overview

Complete implementation for selling products by weight (meat, fruits, vegetables, dairy, bakery) using EAN-13 barcodes that encode both product identity and weight.

Barcode Format
Format: [Type:2][Product:5][Weight:5][Check:1] = 13 digits Example: 2012345015007 +-- 20: Meat type +-- 12345: Product ID +-- 01500: Weight in grams (1.5kg) +-- 7: Check digit

Key Features

EAN-13 Barcode Support

  • Automatic barcode generation
  • Weight encoding in barcode
  • Modulo-10 checksum validation
  • Standard EAN-13 format compatibility

Product Types

  • Type 20: Meat & Poultry
  • Type 21: Fruits & Vegetables
  • Type 22: Dairy Products
  • Type 23: Bakery Items

Price Calculation

  • Automatic price per weight unit
  • Tare weight deduction support
  • Real-time price updates
  • Multiple unit support (kg, g, lbs)

Scale Integration

  • Label-printing scales support
  • External printer integration
  • Android/Tablet solutions
  • PC-based POS integration

System Setup

Step 1: Database Migration

# Run the migration script python add_weight_based_products.py # This adds 8 new fields to products table: - is_weight_based (boolean) - weight_barcode_type (integer 20-23) - weight_price_per_unit (decimal) - weight_unit (varchar: kg, g, lbs) - weight_tare (decimal) - weight_barcode_prefix (varchar) - weight_min_weight (decimal) - weight_max_weight (decimal)

Step 2: Create Weight-Based Products

  1. Go to Products Management
  2. Click "Add New Product"
  3. Check "Weight-Based Product" checkbox
  4. Select Barcode Type (20-23)
  5. Enter Price Per Unit (e.g., P50/kg)
  6. Select Weight Unit (kg, g, lbs)
  7. Set Tare Weight if needed (e.g., 10g for packaging)
  8. Save the product

Step 3: Configure Scale

Scale Configuration Steps
  1. Program product database into scale
  2. Set barcode format to EAN-13
  3. Configure price per unit
  4. Set tare weight if applicable
  5. Test barcode generation

Refer to SCALE_CONFIGURATION_TEMPLATES.md for detailed instructions per scale model

Supported Scale Types

Label-Printing Scales
  • Bizerba GLMI-800: Web interface configuration
  • CAS CL-5000 Series: Keypad programming
  • Toledo 8530: Touchscreen interface
  • Avery Berkel HL122: Keypad config
  • Digi SM-300: Network software
Alternative Solutions
  • Scale + Printer: Any scale with external printer
  • Android/Tablet: Mobile barcode generation apps
  • PC-POS: Computer-based POS integration

Point of Sale Usage

Scanning Weight-Based Products

  1. Weigh the product: Place item on scale
  2. Generate label: Scale prints barcode label with weight
  3. Scan at POS: Scan the barcode at checkout
  4. Auto-calculation: System decodes weight and calculates price
  5. Complete sale: Price displayed automatically

Example Transaction

Product: Beef Steak (Type 20) Price: P250/kg Barcode Scanned: 2012345015007 System Decodes: +-- Type: 20 (Meat) +-- Product ID: 12345 +-- Weight: 01500g (1.5kg) +-- Check: 7 ? Calculation: Weight: 1.5kg Price/kg: P250 Tare: 0kg Total: P375.00

API Endpoints

Method Endpoint Description
POST /api/v1/weight-products/parse-barcode Decode barcode and return product with price
POST /api/v1/weight-products/generate-barcode Generate barcode for product and weight
GET /api/v1/weight-products/ List all weight-based products

Best Practices

Product Setup
  • Use consistent barcode types per category
  • Set realistic min/max weights
  • Include tare weight for packaging
  • Test barcodes before going live
Staff Training
  • Train on proper weighing technique
  • Explain barcode validation
  • Practice with test products
  • Keep quick reference cards handy
Maintenance
  • Calibrate scales regularly
  • Update product prices as needed
  • Check label printer supplies
  • Verify barcode readability
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