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The Point of Sale (POS) feature provides a streamlined interface for registering sales transactions, automatically managing inventory, and calculating profit margins using FIFO costing.

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Overview

The POS system allows you to:
  • Register sales with automatic inventory deduction
  • Link sales to customers for tracking
  • Calculate profit margins using FIFO cost basis
  • Process transactions with custom or suggested pricing
  • View immediate sale confirmation with cost and profit details
The POS feature requires admin or gestor role permissions to access.

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Sale Registration Workflow

1

Select product

Choose the product being sold from the dropdown. The system automatically populates the suggested price, but you can override it.
2

Enter quantity

Specify the quantity being sold. The system validates that sufficient stock is available.
3

Link customer (optional)

Use the stakeholder search to link the sale to a specific customer for tracking purposes.
4

Confirm sale

Submit the transaction. The system automatically:
  • Deducts inventory using FIFO logic
  • Calculates the cost of goods sold (COGS)
  • Computes the profit margin
  • Creates an EXIT movement record
  • Updates batch quantities

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How It Works

The POS system integrates with the inventory movement API to register each sale as an EXIT movement: 
# From PointOfSalePage.jsx:42-49
const dataToSubmit = {
    product_id: selectedProduct,
    customer_id: customerId || null,  // Optional
    quantity: parseInt(quantity, 10),
    unit_price: parseFloat(unitPrice),
    notes: 'POS Sale'
};
const result = await registerSale(dataToSubmit);
This creates a movement record that:
  1. Validates stock availability - Ensures sufficient quantity exists
  2. Applies FIFO costing - Deducts from oldest batches first
  3. Calculates COGS - Sums the unit costs from affected batches
  4. Computes profit - (unit_price - average_cost) × quantity
  5. Updates batches - Reduces quantity_available for each batch used

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FIFO Cost Calculation

The system uses First-In-First-Out logic to determine the cost of goods sold: 
# From stock_service.py:68-72
batches = (
    db.query(Batch)
    .filter(Batch.product_id == product_id, Batch.quantity_available > 0)
    .order_by(Batch.expiration_date.asc(), Batch.purchase_date.asc())
    .all()
)
Example:
  • Product has 3 batches: Batch A (10 units @ 5),BatchB(15units@5), Batch B (15 units @ 6), Batch C (20 units @ $7)
  • Sale: 20 units @ $10 each
  • FIFO deduction: 10 from Batch A + 10 from Batch B
  • COGS: (10 × 5)+(10×5) + (10 × 6) = $110
  • Revenue: 20 × 10=10 = 200
  • Profit: 200−200 - 110 = $90

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Sale Confirmation

After a successful transaction, the POS displays:

Transaction details

  • Movement ID
  • Product name and SKU
  • Quantity sold
  • Unit price
  • Customer (if linked)

Financial summary

  • Total revenue
  • Cost of goods sold (COGS)
  • Profit amount
  • Profit margin percentage

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Integration with Inventory

Each POS sale creates an EXIT movement that:
  • Appears in movement history
  • Updates product stock levels
  • Affects batch quantities
  • Triggers audit logs
  • Impacts inventory valuation reports
You can view all POS sales by filtering movements with notes: "POS Sale" in the movement history.

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User Interface

The POS interface provides:
  1. Product selector - Dropdown with product name and SKU
  2. Quantity input - Numeric input with validation
  3. Price field - Pre-filled with suggested price, editable
  4. Customer search - Optional stakeholder lookup
  5. Submit button - Processes the sale
  6. Confirmation panel - Shows sale details and profit calculation
The suggested price is automatically populated from the product’s suggested_price field, but can be overridden to handle discounts or special pricing.

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Error Handling

The POS system validates:
If the requested quantity exceeds available inventory, the sale is rejected with an error message indicating the maximum available quantity.
If no product is selected or the product ID is invalid, the system prevents submission.
Zero or negative values are rejected. Quantity must be a positive integer, and price must be a positive number.
If a product has no available batches (all depleted), the sale cannot proceed even if the product exists.

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Best Practices

Link customers

Associate sales with customers to enable purchase history tracking and customer analytics.

Use suggested pricing

Keep the suggested price field updated in product management to streamline POS transactions.

Monitor stock levels

Use the dashboard low-stock alerts to prevent failed sales due to depleted inventory.

Review profit margins

Regularly check the profit calculations to ensure pricing strategies are effective.

Stock Movements

View complete movement history including POS sales

Movement API

Technical details of the sale registration endpoint

Customer Management

Manage customer records for sale tracking

Inventory Reports

Analyze sales performance and profitability

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