Реализован обработчик для смены языка аккаунта

api/models/profile/ChangeLanguageForm.php

@@ -0,0 +1,45 @@
+<?php
+namespace api\models\profile;
+
+use api\models\base\ApiForm;
+use common\models\Account;
+use common\validators\LanguageValidator;
+use yii\base\ErrorException;
+
+class ChangeLanguageForm extends ApiForm {
+
+    public $lang;
+
+    private $account;
+
+    public function __construct(Account $account, array $config = []) {
+        $this->account = $account;
+        parent::__construct($config);
+    }
+
+    public function rules() {
+        return [
+            ['lang', 'required'],
+            ['lang', LanguageValidator::class],
+        ];
+    }
+
+    public function applyLanguage() : bool {
+        if (!$this->validate()) {
+            return false;
+        }
+
+        $account = $this->getAccount();
+        $account->lang = $this->lang;
+        if (!$account->save()) {
+            throw new ErrorException('Cannot change user language');
+        }
+
+        return true;
+    }
+
+    public function getAccount() : Account {
+        return $this->account;
+    }
+
+}