Laravel Base model for use with model based validation, compensating for Unique on update

BaseModel.php

<?php

use Eloquent, Validator;

/**
 * Class BaseModel
 * 
 * @package
 */
class BaseModel extends Eloquent {

    /**
     * Used to store errors
     * @var
     */
    protected $errors;

    /**
     *
     */
    public static function boot()
    {
        parent::boot();

        static::creating(function($model)
        {
            if (! property_exists($model, 'rules'))
            {
                return true;
            }
            return $model->validateModel();
        });

        static::updating(function($model)
        {
            if (! property_exists($model, 'rules'))
            {
                return true;
            }
            return $model->validateModel(true);
        });
    }

    /**
     * Validates an object when attempting to save an instance
     * 
     *
     * @param bool $update
     * @return bool
     */
    public function validateModel($update = false)
    {
        if($update)
        {
            $validation = Validator::make($this->getAttributes(), $this->getValidationRules($this->id), $this->getValidationMessages());
        } else {
            $validation = Validator::make($this->getAttributes(), $this->getValidationRules(), $this->getValidationMessages());
        }

        if ($validation->fails())
        {
            $this->errors = $validation->messages();

            return false;
        }

        return true;
    }

    /**
     * Gets the errors
     * 
     * @return mixed
     */
    public function getErrors()
    {
        return $this->errors;
    }

    /**
     * Get validation messages
     * 
     * @return array
     */
    public static function getValidationMessages()
    {
        if (! property_exists(get_called_class(), 'validationMessages'))
        {
            return [];
        }
        $validationMessages = static::$validationMessages;

        return $validationMessages;
    }

    /**
     * Get validation rules and take care of own id on update
     * 
     * @param null $id
     * @return array
     */
    public static function getValidationRules($id = null)
    {

        if (! property_exists(get_called_class(), 'rules'))
        {
            return [];
        }

        $rules = static::$rules;

        if ($id === null)
        {
            return $rules;
        }

        array_walk($rules, function(&$rules, $field) use ($id)
        {
            if (!is_array($rules))
            {
                $rules = explode("|", $rules);
            }

            foreach($rules as $ruleIdx => $rule)
            {
                // get name and parameters
                @list($name, $params) = array_pad(explode(":", $rule, 2), 2, null);

                // only do someting for the unique rule
                if (strtolower($name) != "unique")
                {
                    continue; // continue in foreach loop, nothing left to do here
                }

                $p = array_map("trim", explode(",", $params));

                // set field name to rules key ($field) (laravel convention)
                if (!isset($p[1]))
                {
                    $p[1] = $field;
                }

                // set 3rd parameter to id given to getValidationRules()
                $p[2] = $id;

                $params = implode(",", $p);
                $rules[$ruleIdx] = $name.":".$params;
            }
        });

        return $rules;
    }
}

DemoModel.php

<?php

use Eloquent, SoftDeletingTrait;
use BaseModel;

/**
 * Class DemoModel
 */
class DemoModel extends BaseModel {

    use SoftDeletingTrait;

    protected $dates = ['deleted_at'];

    /**
     * @var string
     */
    protected $table = "demos";
    
    /**
     * @var array
     */
    protected $guarded = ['id', 'deleted_at', 'created_at', 'updated_at'];

    /**
     * @var array
     */
    public static $rules = [
        'slug' => 'required|alpha_dash|unique:demos'
    ];
    /**
     * @var array
     */
    public static $validationMessages = [
        'slug' => 'This is a demo custom message'
    ];

}