ADF Equivalents of Common Oracle Forms Triggers : Pre-Query (Query Processing)

Hello all  ,
today i have in my office have an use case , in which i have apply the "Oracle Forms Triggers in adf "
, i have done it by simply some tricky way ,

so then i decide to write blogs about the
"Equivalents Of Common Oracle forms Triggers", 
in which i will describe how can we achieve the oracle forms like behavior in ADF,

Today's Discussion:
                                  For this time i have select the Pre-query trigger from the category of Query Processing.

first of all let us know the functionality of Pre-Query trigger ,

Pre-Query Trigger:
                                      as we know the trigger is   
"a special kind of stored procedure that automatically executes when an event occurs in the database server"
so a Pre-Query trigger is :
Execute logic before executing a query in a data block.
know let us look how can we do it in ADF.

i will use the HR schema , and for the sake of simplicity just show the some sop in log window to ensure the result 

Solution :

here are simple steps you have to follow to achieve this , 

step1:
           first of all create simple application and create the entities and viewobjects of Departments And employees tables , 

step2: 
          Now double click on one of your view object say
DepartmentsView --> overview ---->Java --> click on pencil button on right top as in figure

Step3:
this will open a window in front of you , check the GenerateViewObject class and under this check the "Include Custome Java data Source Methodes"
as in figure