Forum:

Listbox item selection problem with duplicate labels

Prasad Saya

Rancher

Posts: 517

I like...

posted 10 years ago

Number of slices to send:

Optional 'thank-you' note:

Send

I have a listbox where data is displayed. The problem is when two items in the list have the same label, I am not able to get the correct item details; the item details are different.

I am using MyFaces 2.0 on Tomcat 6.

I am looking for any ideas to solve this. Thanks.

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"  
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml"
	xmlns:f="http://java.sun.com/jsf/core" 
	xmlns:h="http://java.sun.com/jsf/html">
<h:head>
	<title>A JSF List</title>
</h:head>
<h:body>
	<h:form>
		<h3>Items List</h3>
        <h:panelGrid>
			<h:inputText id="name" value="#{bean.itemName}" size="30"
					readonly="true"/>
			<h:inputTextarea id="desc" value="#{bean.itemDesc}"
					rows="2" cols="40"
					readonly="true"/>
			<h:selectOneListbox id="list" size="10" value="#{bean.item}"
					valueChangeListener="#{bean.valueChanged}"
					immediate="true">
				<f:ajax execute="@this" render="msg name desc" />
				<f:selectItems value="#{bean.data}"/>
				<f:attribute name="beanattr" value="#{bean}"/>
				<f:converter converterId="itemConvertor"/>
			</h:selectOneListbox>
        </h:panelGrid>
		<br/><br/>
		<h:outputText id="msg" value="#{bean.message}" />
	</h:form>
</h:body>
</html>

import javax.faces.bean.SessionScoped;
import javax.faces.bean.ManagedBean;
import javax.faces.event.ValueChangeEvent;
import javax.faces.event.ActionEvent;
import java.io.Serializable;
import java.util.List;
import java.util.ArrayList;
@ManagedBean(name="bean")
@SessionScoped
public class ItemsBean implements Serializable {
	private List<Item> data;
	private Item item; // selected item value
	private String msg;
	private String name; // text field value
	private String desc;
	public ItemsBean() {
		loadData();
		if (data.size() == 0) {
			return;
		}
		Item t = data.get(0);
		selectRow(t); // select the first item in the list
	}
	private void selectRow(Item t) {
		setItem(t);
		setItemName(t.getName());
		setItemDesc(t.getDesc());
		setMessage("Selected: " + t.getName());
	}
	private void loadData() {
		data = new ArrayList<>();
		data.add(new Item("item1", "item1 description"));
		data.add(new Item("item2", "item2 description"));
		data.add(new Item("item3", "item3 description"));
		data.add(new Item("item1", "DIFFERENT DESCRIPTION"));
		data.add(new Item("item5", "item5 description"));
	}
	public List<Item> getData() {
		return data;
	}
	public Item getItem() {
		return item;
	}
	public void setItem(Item t) {
		item = t;
	}
	public void valueChanged(ValueChangeEvent e) {
		Item t = (Item) e.getNewValue();
		setMessage("Selected: " + t.getName());
		setItemName(t.getName());
		setItemDesc(t.getDesc());
	}
	public void setMessage(String msg) {
		this.msg = msg;
	}
	public String getMessage() {
		return msg;
	}
	public String getItemName() {
		return name;
	}
	public void setItemName(String n) {
		name = n;
	}
	public String getItemDesc() {
		return desc;
	}
	public void setItemDesc(String d) {
		desc = d;
	}
	// returns the Item object for a given item name
	// method used in converter
	public Item getItemForName(String name) {
		for (Item t : data) {
			if (name.equals(t.getName())) {
				return t;
			}
		}
		return null;
	}
}

SCJP 5, OCPJP 7, 8, SCJD 5, SCWCD 4, SCBCD 5, SCJWS 4, IBM OOAD 833 & 834, MongoDB Developer

Tim Holloway

Saloon Keeper

Posts: 28401

210

I like...

posted 10 years ago

Number of slices to send:

Optional 'thank-you' note:

Send

The "immediate=true" attribute is not some sort of AJAX directive. It's a directive indicating that NO DATA is to be sent to the server when the form is submitted. Not what you want, I don't think.

In HTML, a SELECT list consists of a label and a value. When you make a selection, the value associated with that label is what gets sent back to the server (assuming you didn't have "immediate" in your JSF!)

If 2 labels are identical, it doesn't matter, since the selection list is an ordered collection and the value chosen is based on WHICH label you selected, not on its text value.

Education won't help those who are proudly and willfully ignorant. They'll literally rather die before changing.

Prasad Saya

Rancher

Posts: 517

I like...

posted 10 years ago

Number of slices to send:

Optional 'thank-you' note:

Send

Thanks, for the reply.

You are correct that immediate="true" is not required in this case (but, that was not the problem).

The problem was in the converter. The converter could not associate the selected name with its description. I removed the converter, and made some changes:

- Added a new attribute, item index, to the Item class
- List value is changed from Item object to Item's index: value="#{bean.itemIx}"
- The f:selectItems definition has item name as label and item index as value:
var="itm" itemValue="#{itm.ix}" itemLabel="#{itm.name}"
- And, related changes in the ItemsBean.

This works, fine.

import javax.faces.bean.SessionScoped;
import javax.faces.bean.ManagedBean;
import javax.faces.event.ValueChangeEvent;
import javax.faces.event.ActionEvent;
import java.io.Serializable;
import java.util.List;
import java.util.ArrayList;
@ManagedBean(name="bean")
@SessionScoped
public class ItemsBean implements Serializable {
	private List<Item> data;
	private int ix; // selected item value
	private String msg;
	private String name; // text field value
	private String desc;
	public ItemsBean() {
		loadData();
		if (data.size() == 0) {
			return;
		}
		Item t = data.get(0);
		selectRow(t); // select the first item in the list
	}
	private void selectRow(Item t) {
		setItemIx(0);
		setItemName(t.getName());
		setItemDesc(t.getDesc());
		setMessage("Selected: " + t.getName());
	}
	private void loadData() {
		data = new ArrayList<>();
		data.add(new Item(0, "item1", "item1 description"));
		data.add(new Item(1, "item2", "item2 description"));
		data.add(new Item(2, "item3", "item3 description"));
		data.add(new Item(3, "item1", "DIFFERENT DESCRIPTION"));
		data.add(new Item(4, "item5", "item5 description"));
	}
	public List<Item> getData() {
		return data;
	}
	public int getItemIx() {
		return ix;
	}
	public void setItemIx(int i) {
		ix = i;
	}
	public void valueChanged(ValueChangeEvent e) {
		Integer i = (Integer) e.getNewValue();
		Item t = data.get(i);
		setMessage("Selected: " + t.getName());
		setItemName(t.getName());
		setItemDesc(t.getDesc());
	}
	public void setMessage(String msg) {
		this.msg = msg;
	}
	public String getMessage() {
		return msg;
	}
	public String getItemName() {
		return name;
	}
	public void setItemName(String n) {
		name = n;
	}
	public String getItemDesc() {
		return desc;
	}
	public void setItemDesc(String d) {
		desc = d;
	}
}

SCJP 5, OCPJP 7, 8, SCJD 5, SCWCD 4, SCBCD 5, SCJWS 4, IBM OOAD 833 & 834, MongoDB Developer

Politics n. Poly "many" + ticks "blood sucking insects". Tiny ad:

Gift giving made easy with the permaculture playing cards

https://coderanch.com/t/777758/Gift-giving-easy-permaculture-playing