yiisoft/yii2 · error · InvalidConfigException

The "formName()" method should be explicitly defined for ano

Error message

The "formName()" method should be explicitly defined for anonymous models

What it means

Model::formName() returns the class short name and is the prefix load(), ActiveForm and Html::active* helpers use for input names (POST[formName][attribute]). PHP anonymous classes have no usable short name, so when ReflectionClass::isAnonymous() is true (PHP >= 7) formName() throws InvalidConfigException unless the anonymous class overrides it. The throw usually surfaces indirectly: $model->load($post) calls formName() to match POST keys.

Source

Thrown at framework/base/Model.php:271

     * an empty string, then the input name would be "b".
     *
     * The purpose of the above naming schema is that for forms which contain multiple different models,
     * the attributes of each model are grouped in sub-arrays of the POST-data and it is easier to
     * differentiate between them.
     *
     * By default, this method returns the model class name (without the namespace part)
     * as the form name. You may override it when the model is used in different forms.
     *
     * @return string the form name of this model class.
     * @see load()
     * @throws InvalidConfigException when form is defined with anonymous class and `formName()` method is
     * not overridden.
     */
    public function formName()
    {
        $reflector = new ReflectionClass($this);
        if (PHP_VERSION_ID >= 70000 && $reflector->isAnonymous()) {
            throw new InvalidConfigException('The "formName()" method should be explicitly defined for anonymous models');
        }
        return $reflector->getShortName();
    }

    /**
     * Returns the list of attribute names.
     *
     * By default, this method returns all public non-static properties of the class.
     * You may override this method to change the default behavior.
     *
     * @return string[] list of attribute names.
     */
    public function attributes()
    {
        $class = new ReflectionClass($this);
        $names = [];
        foreach ($class->getProperties(\ReflectionProperty::IS_PUBLIC) as $property) {
            if (!$property->isStatic()) {

View on GitHub (pinned to 66f00d18a2)

Solutions

Override formName() inside the anonymous class: public function formName() { return 'QuickForm'; }
Or skip form-based loading: set attributes directly with setAttributes($data, false) and then call validate()
Or promote the class to a named class file - named classes never hit this guard

Example fix

// before
$model = new class extends \yii\base\Model {
    public $email;
    public function rules() { return [[['email'], 'email']]; }
};
$model->load(Yii::$app->request->post()); // throws

// after
$model = new class extends \yii\base\Model {
    public $email;
    public function rules() { return [[['email'], 'email']]; }
    public function formName() { return 'QuickForm'; }
};
$model->load(Yii::$app->request->post()); // matches POST['QuickForm']['email']

Defensive patterns

Strategy: validation

Validate before calling

$reflector = new \ReflectionClass($model);
if ($reflector->isAnonymous()
    && (new \ReflectionMethod($model, 'formName'))->getDeclaringClass()->getName() === \yii\base\Model::class) {
    // formName() will throw; override it or bypass load()
    $model->setAttributes($data, false);
    $ok = $model->validate();
} else {
    $ok = $model->load($data);
}

Try / catch

try {
    $model->load(Yii::$app->request->post());
} catch (\yii\base\InvalidConfigException $e) {
    // anonymous model without formName() override
    Yii::error($e->getMessage());
    $model->setAttributes(Yii::$app->request->post(), false);
}

Prevention

Always override formName() in anonymous models used with forms
For pure server-side validation use setAttributes() plus validate() instead of load()
Review 'new class extends' near Model in code review as a lint habit

When it happens

Trigger: Creating an inline model `new class extends \yii\base\Model { ... }` and calling load(), rendering it with ActiveForm/ActiveField, or using Html::activeTextInput() on it; calling formName() directly for cache keys or logging on an anonymous model instance.

Common situations: One-off validation models for API payloads written inline to avoid creating a file; anonymous subclasses of Model used in tests and fixtures.

Related errors

AI-assisted analysis of yiisoft/yii2@66f00d18a2 (2026-08-17). Data as JSON: /api/errors/feffdc6888e65073. Report an issue: GitHub.