Completely database, um based dependant drop down menu's.

Question

Ok my mind feels like swiss cheese right now trying to think of a way to do this without it being hard coded (meaning a change to the Database would also require a code change).
I currently have a form with various dropdowns populated via a database. Now (im sure most all of it will have to be recoded due to this) it is required the items be dependant of the primary selection. I.E. main selection is made, the other 4 drop downs get populated with the correct data. I am racking my brain with only using items fromt he database.
I suppose I will present what i was think of doing to get opinions.
Create a result set with rows of all 5 drop downs data. Make an array of just the primary item to use to populate the primary selection box. Now where I am confused is, wouldn't I have to keep the other data in the from of the result set, so when changing a selection of the primary attribute, it would compare said attribute in the resultset.
while(rsData.next()){
i.e. (if selectedItem == rsData.getString("primaryAttribute"))
/*then the 5 items within the current index of the result set can be printed as options in there respective selects.*/
This is what I am not sure about (never have really done javascript before) can this type of logic be done dynamically, i.e. run a while loop such as this and populate the fields, then reset the index on the result set upon the selection of a new primary item.
If im an idiot and way off please tell me, if you have a better way, also please tell me. I just am trying to keep the need for code changes upon database changes to an absolute bare minimum.

Answer 1

you can put all of your lists in session. Then when rendering the page loop through the collections of objects and assign them to a javascript array variable. Then in your javascript method you would use the array to populate your drop downs.
so inside of your javascript tags you would use either scriplets or my preference c:forEach..
<script>
var myArray = new Array()
<c:forEach var="myItems" items="${sessionScope.list1}" varStatus="status">
    myArray[${status.count - 1}] = ${myItems}
</c:forEach>
</script>
or
<script>
var myArray = new Array()
<%
for (int i=0;i<sizeofcollection;i++){
    %>myArray[<%i%>] = <%colection.get(i)%>;<%
%>
</script>then you would be able to use myArray in your javascript function to populate drop downs.
Edited by: gmachamer on Dec 5, 2007 2:35 PM
Edited by: gmachamer on Dec 5, 2007 2:35 PM