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Product Model

The ProductoPOJO represents a product entity in the e-commerce system. It encapsulates product information including identification, name, and price with built-in validation through value objects.

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Model Structure

{
  "id": 67890,
  "nombre": "Laptop Dell XPS 15",
  "precio": {
    "value": 1299.99
  }
}

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Fields

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id
Long
required
Unique identifier for the product.
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nombre
String
required
Product name or title.
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precio
PrecioVO
required
Price value object with built-in validation to ensure price integrity.

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Price Validation

The PrecioVO value object enforces price integrity through constructor validation. Any attempt to create an invalid price will throw an IllegalArgumentException.

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Validation Rules

The price must satisfy ALL of the following conditions:
RuleRequirementException Message
Not NullPrice value cannot be null”El precio no puede ser nulo”
Non-NegativePrice must be >= 0”El precio no puede ser negativo”

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Valid Price Examples

// Valid prices
{
  "precio": { "value": 0.0 }      // Free item
}
{
  "precio": { "value": 9.99 }     // Standard pricing
}
{
  "precio": { "value": 1299.99 }  // High-value item
}
{
  "precio": { "value": 0.01 }     // Minimum non-zero price
}
{
  "precio": { "value": 999999.99 } // Large price
}

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Invalid Price Examples

// Null value
{
  "precio": { "value": null }
}  // IllegalArgumentException: "El precio no puede ser nulo"

// Negative price
{
  "precio": { "value": -10.50 }
}  // IllegalArgumentException: "El precio no puede ser negativo"

// Missing precio object
{
  "nombre": "Product Name"
}  // Validation error

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Creating a Product

{
  "nombre": "Wireless Mouse",
  "precio": {
    "value": 29.99
  }
}

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Updating a Price

The PrecioVO provides an actualizarPrecio() method that creates a new price value object: 
PrecioVO currentPrice = producto.getPrecio();
PrecioVO newPrice = currentPrice.actualizarPrecio(24.99f);
producto.setPrecio(newPrice);
Price value objects are immutable. The actualizarPrecio() method returns a new PrecioVO instance rather than modifying the existing one. This ensures price history and audit trails remain consistent.

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Complete Product Example

{
  "id": 12345,
  "nombre": "Samsung Galaxy S24 Ultra",
  "precio": {
    "value": 1199.99
  }
}

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Price Display and Formatting

The PrecioVO class overrides toString() to return the string representation of the price value: 
PrecioVO precio = new PrecioVO(99.99f);
System.out.println(precio.toString());  // Output: "99.99"
For currency formatting with symbols ($, €, etc.) and locale-specific formatting, implement formatting logic in your presentation layer or API response serializer.

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Business Rules

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Free Products

Products with a price of 0.0 are considered free: 
{
  "id": 999,
  "nombre": "Free Sample Pack",
  "precio": { "value": 0.0 }
}

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Price Updates

When updating product prices:
  • Always create a new PrecioVO instance
  • Log price changes for audit purposes
  • Consider implementing price history tracking
  • Validate business rules (e.g., maximum discount percentages)

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Equality and Comparison

Two PrecioVO objects are equal if their values are equal: 
PrecioVO precio1 = new PrecioVO(99.99f);
PrecioVO precio2 = new PrecioVO(99.99f);
PrecioVO precio3 = new PrecioVO(89.99f);

precio1.equals(precio2);  // true
precio1.equals(precio3);  // false

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API Integration Examples

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GET /productos/

Response
{
  "id": 42,
  "nombre": "Mechanical Keyboard RGB",
  "precio": {
    "value": 149.99
  }
}

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POST /productos

Request
{
  "nombre": "USB-C Hub 7-in-1",
  "precio": {
    "value": 49.99
  }
}
Response (201 Created)
{
  "id": 543,
  "nombre": "USB-C Hub 7-in-1",
  "precio": {
    "value": 49.99
  }
}

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PUT /productos/

Request
{
  "nombre": "USB-C Hub 7-in-1 (Updated)",
  "precio": {
    "value": 39.99
  }
}

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Error Handling

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Invalid Price Errors

400 Bad Request - Null Price
{
  "error": "IllegalArgumentException",
  "message": "El precio no puede ser nulo",
  "field": "precio.value"
}
400 Bad Request - Negative Price
{
  "error": "IllegalArgumentException",
  "message": "El precio no puede ser negativo",
  "field": "precio.value",
  "provided": -25.00
}
  • User Model - User entity with password validation

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Source Code Reference

  • ProductoPOJO: src/main/java/com/example/demo/producto/domain/models/ProductoPOJO.java:11
  • PrecioVO: src/main/java/com/example/demo/producto/domain/vo/PrecioVO.java:6

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