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Wednesday, 2 April 2014

Performing Partial Rollback (Undo Changes) operation in ADF, Stay on current row after rollback

Hello All ,
This post talks about a common requirement of using partial rollback in ADF

Suppose there is two tables on page Departments and Employees, and i have changed one row in Departments table and same time created a row in Employees table, now i want to rollback the changes done in Departments table only

In this case if i use default Rollback operation then it will not only undo the changes of Department table but also remove the newly created row of Employees table
but this was not my purpose.

So to do this kind of things we can use partial rollback operation
  • I have created a fusion web application (Model & VC) using Departments & Employees Table of Oracle's default HR Schema

  • Now drop departments & employees VO on page with it's default operations (CreateInsert, Delete, Execute, Commit & Rollback) and a button to execute partial rollback of departments ViewObject


  • Here in this example i am creating partial rollback for Departments VO only, so to do this add a new transient attribute in Departments Vo to get current state of each row




  • How to get state of each row , in RowImpl class of departments ViewObject , write this code in getter of transient attribute or see my previous blog-post Identifying Modified/newely added row in af:table, get all modified rows of viewobject in bean

  •     /**
         * Gets the attribute value for the calculated attribute RowStatusTrans.
         * @return the RowStatusTrans
         */
        public Integer getRowStatusTrans() {
            /*here row is reference variable of collection, this expression returns an int value if it is
             2-Modified
             0-New
             1-Unmodified
            -1-Initialized
            */
            byte entityState = this.getEntity(0).getEntityState();
            return new Integer(entityState);
        }
    

  • Have created a method to remove newly added row , and to undo changes in existing rows of departments VO in Impl class

  •     /**Method to revert changes of current row
         * @param curRow
         */
        public void revertChangesCurrentRow(Row curRow) {
            if (curRow != null) {
                curRow.refresh(Row.REFRESH_UNDO_CHANGES | Row.REFRESH_WITH_DB_FORGET_CHANGES);
            }
        }
    
        /**Method to check whether row should be removed or not 
         * If it is new - removed
         * If old one- Undo Changes
         * */
        public void revertOrremoveRowValues() {
            ViewObject deptVo = this;
            RowSetIterator deptIter = deptVo.createRowSetIterator(null);
            while (deptIter.hasNext()) {
                Row nextRow = deptIter.next();
                if (nextRow.getAttribute("RowStatusTrans") != null) {
                    Integer rowStatus = (Integer) nextRow.getAttribute("RowStatusTrans");
                    if (rowStatus == 2) {
                        System.out.println("Modified Rows-" + nextRow.getAttribute("DepartmentId"));
                        revertChangesCurrentRow(nextRow);
                    } else if (rowStatus == 0) {
                        System.out.println("New Row Removed");
                        nextRow.remove();
                    }
                }
            }
            this.executeQuery();
        }
    

  • To read more about REFRESH_UNDO_CHANGES and other constants -http://docs.oracle.com/cd/B14099_19/web.1012/b14022/oracle/jbo/Row.html
  • Exposed this method to client and added it to page bindings then called it on Partial Rollback button


  • After running application, i have changed some rows of Departments table and created a new row in employees table


  • Now if i use rollback, it will also remove the new row of employees table, this is the dis-advantage of using rollback


  • Again i have changed some rows of departments table and created a new row in employees table


  • Now see when i click on partial rollback button, it will only undo changes done in department table and employee table is untouched


  • And to stay on current row after partial rollback operation just remove executeQuery from revertOrremoveRowValues() method
Download Sample App
Cheers :-)  Happy Learning

4 comments :

  1. Thanks Ashish for sharing this post .
    Can we retain the filled values of newly added row in Employee table ?,as if we perform partial rollback as you suggested user inserted data (EmpId,FirstName,LastName...)are not retaining only empty row will retain.

    ReplyDelete
    Replies
    1. No, I don't think that you can retain unsaved values
      Suppose you have changed values in a saved row then after partial rollback you'll be able to see DB values
      If you'll call partial rollback on newly created row then it'll be removed

      Ashish

      Delete
  2. Here , you are showing update and add of a row and they are getting reverted. What if I delete a row and I need that back on Cancel?

    ReplyDelete
    Replies
    1. You can use soft deletion for this requirement , check jobinesh's post - Soft Deletion of Rows

      Delete