6.5.2. Invoice Items Model

Now we are going to create a model for items in an invoice:

namespace App;
use Firebird\Eloquent\Model;
use Illuminate\Database\Eloquent\Builder;
class InvoiceLine extends Model {
  /**
   * Table associated with the model
   *
   * @var string
   */
  protected $table = 'INVOICE_LINE';
  /**
   * Primary key of the model
   *
   * @var string
   */
  protected $primaryKey = 'INVOICE_LINE_ID';
  /**
   * Our model does not have a timestamp
   *
   * @var bool
   */
  public $timestamps = false;
  /**
   * The name of the sequence for generating the primary key
   *
   * @var string
   */
  protected $sequence = 'GEN_INVOICE_LINE_ID';
  /**
   * Array of names of computed fields
   *
   * @var array
   */
  protected $appends = ['SUM_PRICE'];
  /**
   * Product
   *
   * @return \App\Product
   */
  public function product() {
    return $this->belongsTo('App\Product', 'PRODUCT_ID');
  }
  /**
   * Amount by item
   *
   * @return double
   */
  public function getSumPriceAttribute() {
    return $this->SALE_PRICE * $this->QUANTITY;
  }
  /**
   * Adding a model object to the database
   * Override this method, because in this case, we work with a stored procedure
   *
   * @param \Illuminate\Database\Eloquent\Builder $query
   * @param array $options
   * @return bool
   */
  protected function performInsert(Builder $query, array $options = []) {
    if ($this->fireModelEvent('creating') === false) {
      return false;
    }
    $connection = $this->getConnection();
    $attributes = $this->attributes;
    $connection->executeProcedure('SP_ADD_INVOICE_LINE', [
      $attributes['INVOICE_ID'],
      $attributes['PRODUCT_ID'],
      $attributes['QUANTITY']
    ]);
    // We will go ahead and set the exists property to true,
    // so that it is set when the created event is fired, just in case
    // the developer tries to update it during the event. This will allow
    // them to do so and run an update here.
    $this->exists = true;
    $this->wasRecentlyCreated = true;
    $this->fireModelEvent('created', false);
    return true;
  }
  /**
   * Saving changes to the current model instance in the database
   * Override this method, because in this case, we work with a stored procedure
   *
   * @param \Illuminate\Database\Eloquent\Builder $query
   * @param array $options
   * @return bool
   */
  protected function performUpdate(Builder $query, array $options = []) {
    $dirty = $this->getDirty();
    if (count($dirty) > 0) {
      // If the updating event returns false, we will cancel
      // the update operation so developers can hook Validation systems
      // into their models and cancel this operation if the model does
      // not pass validation. Otherwise, we update.
      if ($this->fireModelEvent('updating') === false) {
        return false;
      }
      $connection = $this->getConnection();
      $attributes = $this->attributes;
      $connection->executeProcedure('SP_EDIT_INVOICE_LINE', [
        $attributes['INVOICE_LINE_ID'],
        $attributes['QUANTITY']
      ]);
      $this->fireModelEvent('updated', false);
    }
  }
  /**
   * Deleting the current model instance from the database
   * Override this method, because in this case, we work with a stored procedure
   *
   * @return void
   */
  protected function performDeleteOnModel() {
    $connection = $this->getConnection();
    $attributes = $this->attributes;
    $connection->executeProcedure('SP_DELETE_INVOICE_LINE',
      [$attributes['INVOICE_LINE_ID']]);
  }
}

The product function in this model returns the product, actually the App/Product model that was specified as the invoice item. The relation is established through the PRODUCT_ID field by the belongsTo method.

The SumPrice is a calculated field, calculated by the function getSumPriceAttribute. For a calculated field to be available in the model, its name must be specified in the $appends array that stores the names of calculated fields.

Operations

In this model, we redefined the insert, update and delete operations so that they are performed through stored procedures. Along with performing the insert, update and delete operations, these stored procedures recalculate the total in the invoice header. We could have avoided doing that, but then we would have had to modify several models in one transaction. Later, we will examine how to do it that way.