How to gather option values from database in jsp

Question

jsp experts
my problem is that i have to populate the optional values that user has to selecet his choice .
we could have done it by :
<optional value="item1">item1
<optional value="item2">item2
</select>
but in our database if new category of item is enlisted then what ??? ,thats why we go for populating the values from fetching from database by simple class & populate values in the optional values.
can any one help about it

Answer 1

Hi Avina,
You need to invoke a method from your jsp file which interacts with the database. If you are following the MVC pattern which segregates the View and Contoller part, invoke the controller jsp from your View using the include tag.
Say this is the View.jsp
// all your initial page include statements --
<%
// all your java code (if necessary)
%>
<jsp:include page="Controller.jsp" >
<jsp:param name="command" value="getOptionList"/>
</jsp:include>
<!-- all your html tags -->
// If you are following my technique, there should be a Controller.jsp which interacts with your database thru some class which you instantiate in this jsp, which invokes some method (that is why i have passed a parameter, so that if u want to make a check you can do so - u may or may not pass the parameters - based on ur requirements).
Code in Controller.jsp:
<%
// MyClass is the class which does the querying into the database.
// obj.getOptions() is a method in that class which returns a Vector
// containing all the options from your database.
// Please ensure that you import the package in this jsp file, so as
// to get the MyClass.class in this jsp.
String getWhat = request.getParameter("command");
if ( getWhat != null && getWhat.equalsIgnoreCase("command") ) {
MyClass obj = new MyClass();
java.util.Vector optionsAvailable = obj.getOptions();
session.setAttribute("Options", optionsAvailable);
%>
-------------- End of Controller.jsp related work ---------------
// Returning back to the code in the View.jsp:
Once the including is over, the control will return to the next line of code in View.jsp. Just retrieve the data from the session:
Continued - View.jsp
<select name="itemsInDB">
<option value="Select"> Select </option>
<%
/* Now you have a vector containing all the options from
your database. */
java.util.Vector vecOptions = (java.util.Vector)
session.getAttribute("Options");
for (int i=0; i<vecOptions.size(); i++) {
%>
<option value="<%=vecOptions.elementAt(i)%>"><%=vecOptions.elementAt(i)%></option>
<%
%>
</select>
Well thats all thats required. Your problem is solved. You will get a list of all the options in your database. Happy Coding