管理员用户名重复提示

backend/controllers/AdminController.php

@@ -61,6 +61,12 @@ class AdminController extends BaseController
             }
             $model->setAttributes($data);
 
+            //判断用户名重复
+            $count = Admin::find()->where(['username' => $model->username])->count();
+            if ($count > 0) {
+                $this->error('用户名已被占用');
+            }
+
             $model->generateAuthKey();
             $model->setPassword($data['password']);
             $model->platform_id = Yii::$app->user->identity->platform_id;