Yii2 - Generate common error in validation (not related with particular attribute) - validation

Question

I would like to apply a validator for ActiveRecord but not for particular field, I mean, I would like see the validator in the error summary of the form but not associated to a particular field.

Answer 1

When writing a custom validation, you need to use addError method of yii\base\Model (if you write it in model) or yii\validators\Validator (if you write separate validator).
Both methods require $attribute parameter (attribute name) to be passed, and as you can see from the sources, you can't leave it blank:
addError of yii\base\Model:
/**
* Adds a new error to the specified attribute.
* #param string $attribute attribute name
* #param string $error new error message
*/
public function addError($attribute, $error = '')
{
$this->_errors[$attribute][] = $error;
}
addError of yii\validators\Validator:
/**
* Adds an error about the specified attribute to the model object.
* This is a helper method that performs message selection and internationalization.
* #param \yii\base\Model $model the data model being validated
* #param string $attribute the attribute being validated
* #param string $message the error message
* #param array $params values for the placeholders in the error message
*/
public function addError($model, $attribute, $message, $params = [])
{
$params['attribute'] = $model->getAttributeLabel($attribute);
if (!isset($params['value'])) {
$value = $model->$attribute;
if (is_array($value)) {
$params['value'] = 'array()';
} elseif (is_object($value) && !method_exists($value, '__toString')) {
$params['value'] = '(object)';
} else {
$params['value'] = $value;
}
}
$model->addError($attribute, Yii::$app->getI18n()->format($message, $params, Yii::$app->language));
}
Possible options:
1) Select the most important relevant field and add error to it.
2) Select multiple important relevant fields and add the same error message to them (you can store and pass message in separate variable before passing to keep code DRY).
3) You can use not existing attribute name for adding error, let's say all, because attribute existence is not checked at that point.
class YourForm extends \yii\base\Model
{
/**
* #inheritdoc
*/
public function rules()
{
return [
['name', 'yourCustomValidationMethod'],
];
}
/**
* #return boolean
*/
public function yourCustomValidationMethod()
{
// Perform your custom validation here regardless of "name" attribute value and add error when needed
if (...) {
$this->addError('all', 'Your error message');
}
}
}
Note that you still need to attach validator to existing attribute(s) (otherwise exception will be thrown). Use the most relevant attribute.
As a result, you will see error only in error summary. You can display error summary in form like that:
<?= $form->errorSummary($model) ?>
But in most cases there are always one or multiple attributes related with error so I recommend to use option 1 or 2. Option 3 is kind of hack but I think still pretty elegant solution for your problem.