Yii:根据下拉列表选择更改输入文本字段值

<?= $form->field($model, 'dropdown')->dropDownList(['option1' => 'Option 1', 'option2' => 'Option 2'], ['prompt' => 'Select Option']) ?>

public function actionSubmitForm()
{
    $model = new YourModel();

    if ($model->load(Yii::$app->request->post()) && $model->validate()) {
        if ($model->dropdown == 'option1') {
            $model->textField = 'Value for Option 1';
        } elseif ($model->dropdown == 'option2') {
            $model->textField = 'Value for Option 2';
        }

        // 保存模型或执行其他操作

        return $this->redirect(['success']);
    }

    return $this->render('form', ['model' => $model]);
}