rupal82 wrote:
...
now i want to save parent n child record at a time
I am doing
parent.addChild(<childlist>)
and it raise this error..I think parent is not persisted while saving child
or may be you guys can point me in right direction
Why do you use 
@JoinColumn at all? You can use just a 
@OneToMany and 
@ManyToOne mappings. Another note is that you didn't define inverted association end:
Code:
@Entity
public class Parent {
    @Id
    @GeneratedValue
    private Long id;
    @OneToMany(cascade=CascadeType.ALL,fetch=FetchType.LAZY, mappedBy = "parent")
    private List<Child> childs;
    public Long getId() {
        return id;
    }
    public void setId(Long id) {
        this.id = id;
    }
    public List<Child> getChilds() {
        return childs;
    }
    public void setChilds(List<Child> childs) {
        this.childs = childs;
        for (Child child : childs) {
            child.setParent(this);
        }
    }
}
Code:
@Entity
public class Child {
    @Id
    @GeneratedValue
    private Long id;
    @ManyToOne
    private Parent parent;
    public Long getId() {
        return id;
    }
    public void setId(Long id) {
        this.id = id;
    }
    public Parent getParent() {
        return parent;
    }
    public void setParent(Parent parent) {
        this.parent = parent;
    }
}