JSP, BC4J, Row Tag: what is the best way to delete multiple rows?

Question

Hi all.
I have a JSP Edit page with three datasources on it. The tables these VO's represent (A, B and C) have a Parent --> Child (1:1 between A and B) relationship and then another Parent --> Child (1:n between B and C) relationship. So the user retrieves one row for Table A, 1 matching row for table B and then between 0 and 6 matching rows for Table C (there cannot be more than 6 because the user can only add these rows from a finite list).
In my EditSubmit page, I want to perform a RowTag Update action on Tables A and B and they both work no problem. They can't update any rows from Table C but they can add or delete from the list of 0 - 6 rows (the UI is actually a list of 6 checkboxes that they can turn on or off). I figure that the easiest way to handle this rather than keep a list of original values and compare them is simply to delete all existing rows and then add any that the user checked.
This is causing a problem. I have added a hidden field to the form that picks up the RowKey for each existing row. I can get these RowKeys in the Submit page but cannot find a way of using them with the Delete Row Tag.
In the end, the only way I could get it to work was the following code (which I stole from the RowTag.java file in jbohtmlsrc.zip):
if (stakeMailRowKeys != null) {
for (int counter = 0; counter < stakeMailRowKeys.length; counter++) {
Key stakeMailKey = new Key(stakeMailRowKeys[counter], stakeMailingRS.getViewObject().getKeyAttributeDefs());
stakeMailRows = stakeMailingRS.findByKey(stakeMailKey,1);
stakeMailingRow = stakeMailRows[0];
// Tell the row to delete itself from the database
stakeMailingRow.remove();Is there a simpler way to do this (I figure there probably is)? I have another problem with updating the constrained View Objects but I will leave that out of this thread for now.
TIA,
Simon

Answer 1

I don't know if this will help you, but this is what I do:
I separate the logic into a delete.jsp page. If you can create a View Object that will represent the rows you want to delete and append a where clause to select only the rows you want to delete. Then loop through the view deleting each row. Lets just say you have department and employee tables. and you want to delete employees within a given department. Create a view object that brings back all employees.
In your delete.jsp find out the department no. by request.getParameter("dept_id");
then append this to the where clause of your view Object and execute the query:
vo.setWhereClause(request.getParameter("dept_id");
vo.executeQuery;
now loop through and remove the rows:
while(vo.next){
vo.getCurrentRow().remove();
and commit or post changes accordingly.
There are many ways of doing this action. The easiest way I have found is to create the ViewObjects based on what actions you want to take on them. Make bc4j work for you.
regards,
aaron
null