FINERACT-802-restrict-client-to-have-single-self-service-user (#664)

fineract-provider/src/main/java/org/apache/fineract/useradministration/service/AppUserWritePlatformServiceJpaRepositoryImpl.java

@@ -347,6 +347,10 @@ public class AppUserWritePlatformServiceJpaRepositoryImpl implements AppUserWrit
                     username);
         }
 
+        if (realCause.getMessage().contains("'unique_self_client'")) {
+            throw new PlatformDataIntegrityException("error.msg.user.self.service.user.already.exist", "Self Service User Id is already created. Go to Admin->Users to edit or delete the self-service user.");
+        }
+
         logger.error(dve.getMessage(), dve);
         throw new PlatformDataIntegrityException("error.msg.unknown.data.integrity.issue", "Unknown data integrity issue with resource.");
     }

fineract-provider/src/main/resources/sql/migrations/core_db/V354__self_service_user_unique_for_client.sql

@@ -0,0 +1,20 @@
+--
+-- Licensed to the Apache Software Foundation (ASF) under one
+-- or more contributor license agreements. See the NOTICE file
+-- distributed with this work for additional information
+-- regarding copyright ownership. The ASF licenses this file
+-- to you under the Apache License, Version 2.0 (the
+-- "License"); you may not use this file except in compliance
+-- with the License. You may obtain a copy of the License at
+--
+-- http://www.apache.org/licenses/LICENSE-2.0
+--
+-- Unless required by applicable law or agreed to in writing,
+-- software distributed under the License is distributed on an
+-- "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+-- KIND, either express or implied. See the License for the
+-- specific language governing permissions and limitations
+-- under the License.
+--
+
+ALTER TABLE `m_selfservice_user_client_mapping` ADD CONSTRAINT `unique_self_client` UNIQUE (`client_id`);