How to populate selectOneMenu from database table
Hi All,
I am a newbie to JSF. I successfully got selectOneMenu list populated with static values, now I was trying to populate my dropdown list from a database table. Can any one tell me how can I do this? I started using simple tables as follows
tables : dept with dept_code number(4), dept_name varchar2(100)
and emp with emp_code number(4),emp_name varchar2(100),dept_code number(4)
I have already created getter and setters for dept and emp.
I have already created jsp files for dept and emp
Please note that it works when I use static values. This means all of my DB connectivity and hibernate/persistenc setup is fine.
I am using netbeans5.5 with jdk1.6
Please help
Thnx
Alex
# 1
Normally you populate a selectOneMenu after CRUD operations, so your selectOneMenu can grow or shrink dynamically.
Suppose you have a class Member with attributes String name; and int age; plus setter and getter and you want to populate only the name toselectOneMenu
[code]
class Member {
String name;
int age;
//setter and getter for name and age
}
private ArrayList<SelectItem> memberItems = new ArrayList<SelectItem>();
public static void getNameIntoSelectOneMenu() {
List list = "make a query to db to get all Member objets"//hibernate
/*
* these function delete all items in memberItems,otherwise your
*selectOneMenu will have dublicate items
*/
memberItems.removeAll(memberItems);
for (int i = 0; i < list.size(); i++) {
Member m = (Member) list.get(i);
memberItems.add(new SelectItem(m.getName()));
}
}
# 3
memberItems.removeAll(memberItems) ? Rather use clear() .. Or just (re)instantiate it :)
private List<SelectItem> memberItems;
private void loadSelectItems() {
memberItems = new ArrayList<SelectItem>();
List<Member> list = YourDao.execute(someQuery).getOutput(); // retrieve from table
for (Member m : list) {
memberItems.add(new SelectItem(m.getName()));
}
}
# 4
Thnx BalusC for your reply. I copied this code to my EmpBean.java. First of all I did not setup DAO so I was unable to compile. There was error on execute(somequery).getOutput() line. I modified loadSelectItems method in a way to use entitymanager functions as follows
This is my EmpBean code
========================
private List<SelectItem> deptItems;
public void loadSelecttItems() {
deptItems = new ArrayList<SelectItem>();
EntityManagerFactory emf = Persistence.createEntityManagerFactory("learning", new HashMap());
EntityManager em = emf.createEntityManager();
String query = "select dept_code,dept_name from dept";
List<EjbDept> list = em.createQuery(query).getResultList();
for (EjbDept d : list) {
deptItems.add(new SelectItem(d.getDept_Code(),d.getDept_Name()));
}
}
and this is my Emp.jsp code
======================
<h:selectOneMenu id="dept_code" value="#{EmpBean.dept_code}" >
<f:selectItems value="#{EmpBean.deptItems}"/>
</h:selectOneMenu>
and this is my faces-config.xml code
=============================
<managed-bean>
<managed-bean-name>DeptBean</managed-bean-name>
<managed-bean-class>secondproject.DeptBean</managed-bean-class>
<managed-bean-scope>session</managed-bean-scope>
</managed-bean>
<managed-bean>
<managed-bean-name>EmpBean</managed-bean-name>
<managed-bean-class>secondproject.EmpBean</managed-bean-class>
<managed-bean-scope>session</managed-bean-scope>
</managed-bean>
and I am getting exception
======================
org.apache.jasper.JasperException: javax.servlet.jsp.JspException: Error getting property 'deptItems' from bean of type secondproject.EmpBean
org.apache.jasper.servlet.JspServletWrapper.handleJspException(JspServletWrapper.java:510)
....................
.....................
what is missing?
please help, this is my 2nd day just for this :(
