JSP Dependent Drop Down Menu

Hey Guy/Gals!

I need someone help to guide me in creating a drop down menu, where the first menu affects the second menu and it's selection. So in my database I have a category table that has a ID, parentID, and name. parentID is a FK to the PK ID within the same table. Can anyone please give me guidance or some links that may help me. I have been searching the interwebs for the past hour so I don't know how useful links will be to me, since I have literally searched everything. But any help would be nice.

I am guessing I will need to use JSP + AJAX to make this dynamic. Can anyone please help me soon?

<%@ page import="java.io.*,java.util.*,java.sql.*"%>
<%@ page import="javax.servlet.http.*,javax.servlet.*" %>
<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c"%>
<%@ taglib uri="http://java.sun.com/jsp/jstl/sql" prefix="sql"%>

<html>
<head>
<title>SELECT Operation</title>
</head>
<body>

<sql:setDataSource var="snapshot" driver="com.mysql.jdbc.Driver"
     url="jdbc:mysql://uml.cs.uga.edu:3306/team6"
     user="team6"  password="overload"/>

<sql:query dataSource="${snapshot}" var="result">
    SELECT * FROM Category WHERE parentID IS NULL;
</sql:query>


<select>
<c:forEach var="row" items="${result.rows}">
<option value="${row.id}" id="parent_id">${row.name}</option>
</c:forEach>
</select>

<select>
<c:forEach var="row" items="${result.rows}">
<option value="${row.id}" id="parent_id">${row.name}</option>
</c:forEach>
</select>


</body>
</html>

How Category is setup (NOT THE EXACT SCRIPT):
CREATE TABLE Category
CREATE TABLE 'Category'(
    'ID' int(11) , NOT NULL, auto_increment,
    'parentID', int(111),
    'name', varchar(255), NOT NULL,
    PRIMARY KEY ('id')
);

Also 'parentID' is a FK to the PK 'ID'.

Thanks ahead of time for any help!

View Answers

December 3, 2012 at 5:14 PM

The given code will help you to create a dependent dropdown box.

1)country.jsp:

<%@page import="java.sql.*"%>
 <html>
      <head>  
      <script language="javascript" type="text/javascript">  
      var xmlHttp  
      var xmlHttp
      function showState(str){
      xmlHttp=GetXmlHttpObject();
      if (xmlHttp==null)
 {
 alert ("Browser does not support HTTP Request")
 return
 }
      var url="state.jsp";
      url +="?count=" +str;
      xmlHttp.onreadystatechange = stateChange;
      xmlHttp.open("GET", url, true);
      xmlHttp.send(null);
      }

      function stateChange(){   
      if (xmlHttp.readyState==4 || xmlHttp.readyState=="complete"){   
      document.getElementById("state").innerHTML=xmlHttp.responseText   
      }   
      }

function GetXmlHttpObject()
{
var xmlHttp=null;
try
 {
 // Firefox, Opera 8.0+, Safari
 xmlHttp=new XMLHttpRequest();
 }
catch (e)
 {
 //Internet Explorer
 try
  {
  xmlHttp=new ActiveXObject("Msxml2.XMLHTTP");
  }
 catch (e)
  {
  xmlHttp=new ActiveXObject("Microsoft.XMLHTTP");
  }
 }
return xmlHttp;
}
      </script>  
      </head>  
      <body>  
      <select name='country' onchange="showState(this.value)">  
      <option value="none">Select</option>  
    <%
 Class.forName("com.mysql.jdbc.Driver").newInstance();  
 Connection con = DriverManager.getConnection("jdbc:mysql://localhost:3306/test","root","root");  
 Statement stmt = con.createStatement();  
 ResultSet rs = stmt.executeQuery("Select * from country");
 while(rs.next()){
     %>
      <option value="<%=rs.getString(1)%>"><%=rs.getString(2)%></option>  
      <%
 }
     %>
      </select>  
      <br>  
      <div id='state'>  
      <select name='state' >  
      <option value='-1'></option>  
      </select>  
      </div>  
      </body> 
      </html>

2)state.jsp:

 <%@page import="java.sql.*"%>
<%
String country=request.getParameter("count");  
 String buffer="<select name='state' ><option value='-1'>Select</option>";  
 try{
 Class.forName("com.mysql.jdbc.Driver").newInstance();  
 Connection con = DriverManager.getConnection("jdbc:mysql://localhost:3306/test","root","root");  
 Statement stmt = con.createStatement();  
 ResultSet rs = stmt.executeQuery("Select * from state where countryid='"+country+"' ");  
   while(rs.next()){
   buffer=buffer+"<option value='"+rs.getString(1)+"'>"+rs.getString(3)+"</option>";  
   }  
 buffer=buffer+"</select>";  
 response.getWriter().println(buffer); 
 }
 catch(Exception e){
     System.out.println(e);
 }

 %>

For the above code, we have created two database tables:

CREATE TABLE `country` (                                 
           `countryid` bigint(255) NOT NULL auto_increment,       
           `countryname` varchar(255) default NULL,               
           PRIMARY KEY  (`countryid`)); 



CREATE TABLE `state` (                                   
          `stateid` bigint(255) NOT NULL auto_increment,         
          `countryid` int(255) default NULL,                     
          `state` varchar(255) default NULL,                     
          PRIMARY KEY  (`stateid`));

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