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Material Model

The Material model manages the materials catalog and validates material availability for specific rooms. It ensures that only materials associated with a room can be requested for reservations.

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Constructor

public function __construct()
Initializes the Material model and establishes a PDO database connection.

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Methods

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getAll()

Retrieves all materials from the catalog. Useful for administration purposes. 
public function getAll(): array
Returns: array - Array of associative arrays containing all materials, ordered alphabetically by name
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id
int
Material ID
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name
string
Material name
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description
string
Material description
SQL Query: 
SELECT id, name, description 
FROM materials 
ORDER BY name
Example: 
$material = new Material();
$allMaterials = $material->getAll();

foreach ($allMaterials as $m) {
    echo "[{$m['id']}] {$m['name']}: {$m['description']}\n";
}

// Output:
// [1] Micrófono inalámbrico: Para eventos y conferencias
// [2] Proyector: Proyector Full HD
// [3] Pantalla: Pantalla de proyección retráctil

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getByRoom()

Retrieves all materials available for a specific room, including quantity information. 
public function getByRoom(int $roomId): array
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roomId
int
required
The ID of the room
Returns: array - Array of materials associated with the room, ordered alphabetically by name
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id
int
Material ID
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name
string
Material name
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description
string
Material description
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quantity
int
Quantity available in this specific room
SQL Query: 
SELECT 
    m.id,
    m.name,
    m.description,
    rm.quantity
FROM room_materials rm
JOIN materials m ON m.id = rm.material_id
WHERE rm.room_id = :room_id
ORDER BY m.name
Example: 
$material = new Material();
$roomMaterials = $material->getByRoom(3);

echo "Materials available in this room:\n";
foreach ($roomMaterials as $m) {
    echo "- {$m['name']} (Qty: {$m['quantity']})\n";
    echo "  {$m['description']}\n";
}

// Output:
// Materials available in this room:
// - Micrófono inalámbrico (Qty: 4)
//   Para eventos y conferencias
// - Proyector (Qty: 1)
//   Proyector Full HD

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existsInRoom()

Verifies if a specific material is available in a specific room. Used for backend security validation. 
public function existsInRoom(int $materialId, int $roomId): bool
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materialId
int
required
The ID of the material to check
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roomId
int
required
The ID of the room to check
Returns: bool - true if the material exists in the room, false otherwise SQL Query: 
SELECT 1
FROM room_materials
WHERE material_id = :material_id
  AND room_id = :room_id
LIMIT 1
This method is used for backend security validation. Never trust frontend-submitted material IDs without validating they belong to the requested room.
Example: 
$material = new Material();

// Check if Material #5 is available in Room #3
if ($material->existsInRoom(5, 3)) {
    echo "Material is available in this room";
} else {
    echo "Material is NOT available in this room";
}
Security Use Case: 
// User submits a reservation request with material IDs
$requestedMaterials = $_POST['materials']; // [2, 5, 8]
$roomId = $_POST['room_id']; // 3

$material = new Material();

// Validate each material belongs to the room
foreach ($requestedMaterials as $matId) {
    if (!$material->existsInRoom($matId, $roomId)) {
        http_response_code(400);
        echo json_encode([
            'error' => 'Invalid material ID for this room',
            'material_id' => $matId
        ]);
        exit;
    }
}

// All materials are valid, proceed with reservation...

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validateForRoom()

Validates that all materials in an array belong to a specific room. Convenient for batch validation. 
public function validateForRoom(array $materialIds, int $roomId): bool
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materialIds
array
required
Array of material IDs to validate
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roomId
int
required
The ID of the room to validate against
Returns: bool - true if all materials are valid for the room, false if any material is invalid
This method:
  1. Returns true for empty arrays (no materials requested is valid)
  2. Normalizes input: filters out invalid values, converts to integers, removes duplicates
  3. Validates each material ID using existsInRoom()
Example: 
$material = new Material();

// Validate multiple materials at once
$requestedMaterials = [2, 5, 8, 10];
$roomId = 3;

if ($material->validateForRoom($requestedMaterials, $roomId)) {
    echo "All materials are valid for this room";
} else {
    echo "One or more materials are not available in this room";
}
Input Normalization: The method automatically handles various input formats: 
$material = new Material();

// These inputs are normalized:
$material->validateForRoom([1, 2, 3], 5);           // Valid integers
$material->validateForRoom(['1', '2', '3'], 5);     // String numbers → converted to int
$material->validateForRoom([1, 2, 2, 3], 5);        // Duplicates → removed
$material->validateForRoom([1, 0, -5, 3], 5);       // Invalid IDs → filtered out
$material->validateForRoom([], 5);                  // Empty → returns true
Complete Validation Flow: 
$material = new Material();

// Example: Processing a reservation form submission
$roomId = $_POST['room_id'];
$materialIds = $_POST['material_ids']; // Can be null or empty

// Ensure we have an array
if (!is_array($materialIds)) {
    $materialIds = [];
}

// Validate materials
if (!$material->validateForRoom($materialIds, $roomId)) {
    http_response_code(400);
    echo json_encode([
        'error' => 'One or more selected materials are not available for this room',
        'room_id' => $roomId,
        'invalid_materials' => $materialIds
    ]);
    exit;
}

// Materials are valid, proceed with creating reservation
echo "All validations passed";
Comparison: existsInRoom() vs validateForRoom() 
// Use existsInRoom() when:
// - Checking a single material
// - Need to identify WHICH material is invalid

$material = new Material();
foreach ($materialIds as $matId) {
    if (!$material->existsInRoom($matId, $roomId)) {
        echo "Invalid material: {$matId}";
        break;
    }
}

// Use validateForRoom() when:
// - Checking multiple materials
// - Only need to know if ALL are valid (boolean result)
// - Want automatic input normalization

if (!$material->validateForRoom($materialIds, $roomId)) {
    echo "Validation failed";
}

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Database Schema

The Material model interacts with the following database tables:
  • materials - Material catalog
    • id - Primary key
    • name - Material name
    • description - Material description
  • room_materials - Junction table linking rooms to materials
    • room_id - Foreign key to rooms table
    • material_id - Foreign key to materials table
    • quantity - Quantity available in the room

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Best Practices

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Always Validate Materials

Never trust frontend submissions. Always validate materials server-side: 
// BAD: Trusting user input
$reservation->attachMaterials($reservationId, $_POST['materials']);

// GOOD: Validating first
$material = new Material();
if ($material->validateForRoom($_POST['materials'], $roomId)) {
    $reservation->attachMaterials($reservationId, $_POST['materials']);
} else {
    throw new Exception('Invalid materials for this room');
}

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Handle Empty Material Lists

Not all reservations require materials: 
$materialIds = $_POST['materials'] ?? [];

// validateForRoom() returns true for empty arrays
if ($material->validateForRoom($materialIds, $roomId)) {
    if (!empty($materialIds)) {
        $reservation->attachMaterials($reservationId, $materialIds);
    }
}

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Display Materials to Users

When building forms, only show materials available for the selected room: 
$material = new Material();
$roomId = 3;
$availableMaterials = $material->getByRoom($roomId);

// Generate checkboxes for each material
foreach ($availableMaterials as $m) {
    echo "<label>";
    echo "<input type='checkbox' name='materials[]' value='{$m['id']}'>";
    echo "{$m['name']} (Available: {$m['quantity']})";
    echo "</label>";
}

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Inventory Management

Use quantity information for inventory tracking: 
$material = new Material();
$roomMaterials = $material->getByRoom($roomId);

foreach ($roomMaterials as $m) {
    if ($m['quantity'] < 2) {
        echo "⚠️ Low stock: {$m['name']} (Only {$m['quantity']} available)\n";
    }
}

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