Dropdown creation dynamically from DB lookup

[Dushyant Chhetri]

Hi All,

I am trying to create a dropdown menu on using struts2 .
I am implementing the UI on jsp with struts taglib.

Now I want to populate the data on the dropdown froma database.
For this I have used the following and created an arraylist

<s:form action="IssueItems">
 
<%Connection con=DBDriverConn.getConnection();
Statement st=con.createStatement();
ResultSet r1=st.executeQuery("select * from hardware_list ");
		%>
<%List<String> hardwarelist= new ArrayList<String>();
while(r1.next()){
	hardwarelist.add(r1.getString(1));}
%>

<%System.out.println("list size is "+hardwarelist.size());
for(int i= 0; i < (hardwarelist.size());i++){
	System.out.println("Item "+i+" "+hardwarelist.get(i));
}
%>
 
<h4>
	<s:select label="Select Hardware" 
		headerKey="-1" headerValue="Select Device" 
		list="hardwarelist"	
//commenetd		*Using this gives result   list="#{'1':'Jan', '2':'Feb', '3':'Mar', '4':'Apr'}" 
		name="selectedDevice"/>
</h4> 
 
<s:submit value="submit" name="submit" />
 
</s:form>

The action for the above submit form is

package com.model;

import com.opensymphony.xwork2.ActionSupport;

public class IssueItems extends ActionSupport{
	
	private String selectedDevice;
	
	public String execute() {
        return SUCCESS;
    }
	public String issue(){
		System.out.println("in issue method ");
		System.out.println("here "+getSelectedDevice());
		return new String("issued");
	}
	public String getSelectedDevice() {
		return selectedDevice;
	}
	public void setSelectedDevice(String selectedDevice) {
		this.selectedDevice = selectedDevice;
	}

}

However I am getting the following error

Oct 22, 2011 4:45:06 PM org.apache.catalina.core.StandardWrapperValve invoke
SEVERE: Servlet.service() for servlet jsp threw exception
tag 'select', field 'list', name 'selectedDevice': The requested list key 'hardwarelist' could not be resolved as a collection/array/map/enumeration/iterator type. Example: people or people.{name} - [unknown location]
	at org.apache.struts2.components.Component.fieldError(Component.java:231)

Please suggest me where I am going wrong.

[Sunil Sunny]

boss you are uing MVC architecture why you are performing "database operations" on your view. i would suggest you to create an action first and you must create a list in its execute function. and
1. you must declare a "List Type Variable" hardware list.2. Fill the list as you have filled in your UI.
3. then create setter and getter for that List variable "hardwarelist".
4. after that you can set <s:select list="hardwarelist" headerKey="0" headerValue="Select Device" />
this will work



Remember list attribute of select will be same as the list variable name you declar in your action.


Do not forget to make entry in Struts.xml as:

<action name="Your cation in which you have mak your list" class="the action class">
<result name="success">YourJsp Page</result>

</action>