# Yii 1 validators

Yii has many built in [system validators](https://www.yiiframework.com/doc/api/1.1#system.validators).

## Yii Length validator

```php
public function rules()
{
    return [
        ['code', 'length', 'is' => 13],
        ['last_name', 'length', 'min' => 2, 'tooShort' => 'Last name should be more than 2 chars'],
        ['office_id', 'length', 'max' => 100, 'tooLong' => 'Office Id cannot be more than 100'],
    ];
}
```

## Yii 1 date validator

See [date validation docs](https://www.yiiframework.com/doc/api/1.1/CDateValidator).

Example of usage:

```php
public function rules()
{
    return [
        ['published_on', 'date', 'dateFormat' => 'dd.MM.yyyy'],
    ];
}
```

### How to create Yii custom dateValidator

**Important:** Don't reinvent the weel, because Yii 1 has built-in [date](https://www.yiiframework.com/doc/api/1.1/CDateValidator) validator.

If you want to write your own custom date validator you can create file at `protected/components/validators/` folder. 
This validator uses [DateTime::createFromFormat](https://www.php.net/manual/en/datetime.createfromformat.php) function, 
that returns `false` on failure.

```php
class dateValidator extends CValidator
{
    public $dateFormat = 'd.m.Y';
    
    public $message = 'Invalid date format';

    protected function validateAttribute($object, $attribute)
    {
        // Let another validator to check empty value
        if (empty($object->$attribute)) {
            return;
        }

        $dateString = $object->$attribute;

        $date = DateTime::createFromFormat($this->dateFormat, $dateString);

        if ($date === false) {
            $this->addError($object, $attribute, $this->message);
        }
    }
}
```

To use this validator, just add this line to your `rules()` method:

```php
    public function rules()
    {
        return [
            // By default 'dateFormat' param has value 'd.m.Y'
            ['published_on', 'dateValidator', 'dateFormat' => 'Y-m-d'],
        ];
    }
```