~~Title: Server-Side Trigger for Storages~~

With JVx, the business logic can be developed in either the database or the middle tier. For the development of the business logic entirely in the middle tier, so-called server-side triggers are required. These triggers work just like the [[jvx:client:model:databook:events|DataBook events]] at the client.

For example, a server-side trigger is called when a new record was inserted, modified, or deleted.

== Example ==

We use a RemoteDataBook at the client for the creation of user accounts. A user is defined by username, password, first name, and last name. The password, however, has to be encrypted before it is stored in the database.

We define the storage:

<file java>
public DBStorage getUsers() throws Exception
{
   DBStorage users = (DBStorage)get("users");
   if (users == null)
   {
      users = new DBStorage();
      users.setDBAccess(getDBAccess());
      users.setWritebackTable("USERS");
      users.open();
      
      users.eventBeforeInsert().addListener(this, "doEncryptPwd");
      users.eventBeforeUpdate().addListener(this, "doEncryptPwd");

      put("users", users);
   }
   return users;
}
</file>

and the trigger to insert and update:

<file java>
public void doEncryptPwd(StorageEvent pEvent) throws Exception
{
   IBean bn = pEvent.getNew();
   
   String sNew = (String)bn.get("PASSWORD");
   String sOld;
   
   IBean bnOld = pEvent.getOld();
   
   if (bnOld != null)
   {
      sOld = (String)bnOld.get("PASSWORD");
   }
   else
   {
      sOld = null;
   }
   
   if (!CommonUtil.equals(sOld, sNew))
   {
      bn.put("PASSWORD", AbstractSecurityManager.getEncryptedPassword(
                         SessionContext.getCurrentSessionConfig(), sNew));
   }
}
</file>

In our example, we use IBean to access the properties. The event also allows the use of POJOs, as shown in the following example:

<file java>
public void doEncryptPwd(StorageEvent pEvent)
{
    ...
    ...
    User user = pEvent.getNew(User.class);     

    user.setPassword(AbstractSecurityManager.getEncryptedPassword(
                     SessionContext.getCurrentSessionConfig(),
                     user.getPassword()));
}
</file>

\\ 
**<fs 20px>Note</fs>**

Any POJO can be used. The implemented mechanism attempts to align the properties via the database´s column identifiers. In our previous example, we could also use an Address POJO, as long as it contains the relevant properties. Only feasible properties are aligned.