Рефакторинг. В АПИ добавлены методы в изменения: username, email, password

frontend/modules/api/models/profile/ProfileChangeEmailForm.php

@@ -0,0 +1,32 @@
+<?php
+
+namespace frontend\modules\api\models\profile;
+use yii\base\Model;
+
+class ProfileChangeEmailForm extends Model
+{
+
+    public $newEmail;
+
+    /**
+     * @return array
+     */
+    public function rules()
+    {
+        return [
+            [['newEmail'], 'string'],
+            [['newEmail'], 'required'],
+            [['newEmail'], 'email'],
+            ['newEmail', 'unique', 'targetAttribute' => 'email', 'targetClass' => User::class],
+        ];
+    }
+
+    /**
+     * @return string
+     */
+    public function formName(): string
+    {
+        return '';
+    }
+
+}