Question

I am trying to implement a simple join operation with my two tables ,using hibernate 3 annotaions with spring3 mvc.

I have two tables:

Employee

CREATE TABLE IF NOT EXISTS `employee` (`enter code here`
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `name` varchar(100) NOT NULL,
  `address1` varchar(100) NOT NULL,
  `address2` varchar(100) NOT NULL,
  `created_at` datetime NOT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB

Salary

CREATE TABLE IF NOT EXISTS `salary` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `employee_id` int(11) NOT NULL,
  `basic_pay` int(5) NOT NULL,
  `take_home` int(5) NOT NULL,
  PRIMARY KEY (`id`),
  KEY `employee_id` (`employee_id`)
) ENGINE=InnoDB

I have created two annotated modal classes:

Employee.java

@Entity
@Table(name = "employee", catalog = "employee")
public class Employee implements java.io.Serializable {

    private Integer id;
    private String name;
    private String address1;
    private String address2;
    private Date createdAt;
    private Set salaries = new HashSet(0);

    public Employee() {
    }

    public Employee(String name, String address1, String address2,
            Date createdAt) {
        this.name = name;
        this.address1 = address1;
        this.address2 = address2;
        this.createdAt = createdAt;
    }

    public Employee(String name, String address1, String address2,
            Date createdAt, Set salaries) {
        this.name = name;
        this.address1 = address1;
        this.address2 = address2;
        this.createdAt = createdAt;
        this.salaries = salaries;
    }

    @Id
    @GeneratedValue(strategy = IDENTITY)
    @Column(name = "id", unique = true, nullable = false)
    public Integer getId() {
        return this.id;
    }

    public void setId(Integer id) {
        this.id = id;
    }

    @Column(name = "name", nullable = false, length = 100)
    public String getName() {
        return this.name;
    }

    public void setName(String name) {
        this.name = name;
    }

    @Column(name = "address1", nullable = false, length = 100)
    public String getAddress1() {
        return this.address1;
    }

    public void setAddress1(String address1) {
        this.address1 = address1;
    }

    @Column(name = "address2", nullable = false, length = 100)
    public String getAddress2() {
        return this.address2;
    }

    public void setAddress2(String address2) {
        this.address2 = address2;
    }

    @Temporal(TemporalType.TIMESTAMP)
    @Column(name = "created_at", nullable = false, length = 0)
    public Date getCreatedAt() {
        return this.createdAt;
    }

    public void setCreatedAt(Date createdAt) {
        this.createdAt = createdAt;
    }

    @OneToMany(fetch = FetchType.LAZY, mappedBy = "employee")
    public Set getSalaries() {
        return this.salaries;
    }

    public void setSalaries(Set salaries) {
        this.salaries = salaries;
    }

Salary.java

@Entity
@Table(name = "salary", catalog = "employee")
public class Salary implements java.io.Serializable {

    private Integer id;
    private Employee employee;
    private int basicPay;
    private int takeHome;

    public Salary() {
    }

    public Salary(Employee employee, int basicPay, int takeHome) {
        this.employee = employee;
        this.basicPay = basicPay;
        this.takeHome = takeHome;
    }

    @Id
    @GeneratedValue(strategy = IDENTITY)
    @Column(name = "id", unique = true, nullable = false)
    public Integer getId() {
        return this.id;
    }

    public void setId(Integer id) {
        this.id = id;
    }

    @ManyToOne(fetch = FetchType.LAZY)
    @JoinColumn(name = "employee_id", nullable = false)
    public Employee getEmployee() {
        return this.employee;
    }

    public void setEmployee(Employee employee) {
        this.employee = employee;
    }

    @Column(name = "basic_pay", nullable = false)
    public int getBasicPay() {
        return this.basicPay;
    }

    public void setBasicPay(int basicPay) {
        this.basicPay = basicPay;
    }

    @Column(name = "take_home", nullable = false)
    public int getTakeHome() {
        return this.takeHome;
    }

    public void setTakeHome(int takeHome) {
        this.takeHome = takeHome;
    }

when i open a page i got the following error

org.springframework.beans.factory.BeanCreationException: Error creating bean 
with name 'sessionFactory' defined in ServletContext resource [/WEB-INF/spring-servlet.xml]: 
Invocation of init method failed; nested exception is org.hibernate.MappingException: 
Could not determine type for: java.util.Set, at table: EMPLOYEE, for columns: 
[org.hibernate.mapping.Column(salaries)]

Anything wrong on my modal class

Help is highly appreciated,
Thanks,
VKS

Answer 1

I am not an expert, But dnt we need to tell hibernate that what should be the type of SET. because in this case, it seems to me that we are telling hibernate SET represents one to many relationship, but with which table ??

In *.hbm.xml mapping files, I guess “table” attribute was used for this purpose.

e.g.

<set cascade="persist, merge, save-update, evict, replicate, lock, refresh" name="Salaries" inverse="true" lazy="true" table="salary">
            <key>
               //code goes here
            </key>
            <one-to-many class="Salary" />
        </set>