JPA OneToMany MappedBy relationships

Question

I have three classes, Site, GoupIP and IP

A Site has one or many GrouIPs. A GroupIP has one or many IPs.

Here is the code:

Site

@Entity
@Table(name = "site")
public class Site implements Serializable {
private Set<GroupIp> groups;

@OneToMany(mappedBy = "site", fetch = FetchType.EAGER, cascade =CascadeType.ALL)
public Set<GroupIp> getGroups() {
    return groups;
}

public void setGroups(Set<GroupIp> groups) {
    this.groups = groups;
}

}

GroupIP

@Entity
@Table(name = "groupip")
public class GroupIp implements Serializable {
private Set<Ip> ips;
private Site site;

@ManyToOne(cascade = CascadeType.MERGE)
@JoinColumn(name = "site_id")
public Site getSite() {
return site;
}

@OneToMany(mappedBy = "groupip", fetch = FetchType.EAGER, cascade =CascadeType.ALL)
public Set<Ip> getIps() {
    return ips;
}

public void setIps(Set<Ip> ips) {
    this.ips= ips;
}

}

IP

@Entity
@Table(name = "ip")
public class Ip implements Serializable {
private GroupIp groupIp;

@ManyToOne(targetEntity = GroupIp.class,cascade = CascadeType.MERGE)
@JoinColumn(name = "groupip_id", nullable=false)
public GroupIp getGroupIp() {
return groupIp;
}

public void setGroupIp(GroupIp groupIp) {
        this.groupIp = groupIp;
}

}

On GroupIp class, I m getting:

In attribute 'ips', the "mapped by" value 'groupip' cannot be resolved to an attribute on the target entity.

Whats wrong on my code ??

Answer 1

The mappedBy name that you have to put in the relationship is the name of the class attribute, not the table name.

So put @OneToMany(mappedBy = "groupIp",... (note the uppercase) instead of @OneToMany(mappedBy = "groupip",...