Newbie: Help With Mappings

gdboling · **Joined:** Fri Jan 16, 2004 4:58 pm **Posts:** 37

I am using Hibernate 2.1.4

I have the following psuedo tables

[Employee]
empid (pk)
firstname
lastname
department
email

--------------------

[User]
userid (pk/fk to Employee.empid)
password
role
status

--------------------

[System]
systemid
systemname

---------------------

[Issue]
issueid (pk)
issuenumber
datecreated
datemodified
problemtext
createdby (fk User.userid)
acceptedby (fk User.userid)
closedby (fk User.userid)
assignedto (fk User.userid)
employeeid ((fk Employee.empid)
systemId (fk System.systemid)

----------------------

And I am having a really hard time figuring out some mappings. Here is what I have so far

[Issue.hbm.xml]

Code:

<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping
    PUBLIC "-//Hibernate/Hibernate Mapping DTD//EN"
    "http://hibernate.sourceforge.net/hibernate-mapping-2.0.dtd">

<hibernate-mapping>

    <class name="com.intrustbank.anykey.beans.Issue" table="issue_table">

        <id name="issueId" type="int" column="isueid" unsaved-value="0">
            <generator class="identity"/>
        </id>

        <property name="dateCreated" column="datecreated"  type="java.util.Date" />
        <property name="dateModified" column="datemodified"  type="java.util.Date"/>
        <property name="issueNumber" column="issuenumber" type="java.lang.String"/>

         <many-to-one 
            name="systemId" 
            column="systemid" 
            class="com.intrustbank.anykey.beans.System" 
            not-null="false" />
        

        <property name="additionalInfo" column="problemtext" type="java.lang.String"/>

        <many-to-one 
            name="createdBy" 
            column="createdby" 
            class="com.intrustbank.anykey.beans.User" 
            not-null="false" />
        
    </class>

</hibernate-mapping>

[Employee.java]

Code:

package com.intrustbank.anykey.beans;

public class Employee
{
    private int empId;
    private String firstName;
    private String lastName;
    private String department;
    private String email;

    public int getEmpId() {
        return empId;
    }

    public void setEmpId(int empId) {
        this.empId = empId;
    }

    public String getFirstName() {
        return firstName;
    }

    public void setFirstName(String firstName) {
        this.firstName = firstName;
    }

    public String getLastName() {
        return lastName;
    }

    public void setLastName(String lastName) {
        this.lastName = lastName;
    }

    public String getDepartment() {
        return department;
    }

    public void setDepartment(String department) {
        this.department = department;
    }

    public String getEmail() {
        return email;
    }

    public void setEmail(String email) {
        this.email = email;
    }
}

[User.java]

Code:

package com.intrustbank.anykey.beans;

public class User extends Employee 
{
   private String role;
   private String email;
   private int status;

   public String getRole() {
        return role;
    }

    public void setRole(String role) {
        this.role = role;
    }

    public int getStatus() {
        return status;
    }

    public void setStatus(int status) {
        this.status = status;
    }


}

Can someone tell me if I am even on the right track here? Sorry for the length of the post. :)

subpaul · **Joined:** Thu Jul 22, 2004 2:15 pm **Posts:** 35

you are on the right track.. for the most part?

it seems like everyone of your Employees is a User also? then why another table?

public class User extends Employee

this should be mapped something like:

<hibernate-mapping>

<class name="com.intrustbank.anykey.beans.Employee"
...... rest of the stuff
......

<subclass name="User" discriminator-value="U">
<property name="password"/>
<property name="role"/>
<property name="status"/>
</subclass>

</class>

</hibernate-mapping>

and your table should look like:
[Employee]
empid (pk)
firstname
lastname
department
email
password
role
status

gdboling · **Joined:** Fri Jan 16, 2004 4:58 pm **Posts:** 37

Thanks. The reason I had a User Table and an Employee table is because there are 1500 Employees. Only 12 are users of this system. So I thought it better to sepearte the 2 tables. Is that bad design?

gdboling · **Joined:** Fri Jan 16, 2004 4:58 pm **Posts:** 37

Also, if I needed to get a list of all Users, it would be easier to pull that from a User table than to try and filter the Employees or adding an extra column called user (yes/no).

ernst_pluess · **Posted:** Thu Aug 05, 2004 4:11 pm

IMHO having a separate table for employee and user isn't a good idea, unless you really know that you have to do it like that. This is especially true if you have to acess the data without Hibernate's help as well. Generally speaking: Having all classes of hirarchy in one table is the simplest solution.

Hibernate in Action has a very nice description about this in chapter "3.6 Mapping class inheritance". You can get an online verison at http://www.manning.com.

HTH
Ernst