org.hibernate.MappingException: Repeated column in mapping for entity

database-design, domain-driven-design, hibernate, java

Solution

You use the same `@JoinColumn` for voter and person. Change to `@JoinColumn("personID")` for associated person and `@JoinColumn("voterID")` for associated voter and all should be fine.

As a side note because you tagged this with `domain-driven-design`... Your vote class would be more DDD style if implemented like this:

@Id
@GeneratedValue(strategy = GenerationType.AUTO)
@Column(name = "ID")
private Integer ID;

@ManyToOne
@JoinColumn(name = "voterID")
private Person voter;

@ManyToOne
@JoinColumn(name = "votedForID")
private Person votedFor;

@Column(name = "vote")
private Boolean vote;

public void cast(Person voter, Person votedFor, boolean vote) {
    // Maybe assert that this vote has not already been casted
    this.voter = voter;
    this.votedFor = votedFor;
    this.vote = vote;
}

public Integer getID() {
    return ID;
}

public Boolean isUpVote() {
    return vote;
}

public Boolean isDownVote() {
    return !vote;
}

public Person getVoter() {
    return voter;
}

public Person getVotedFor() {
    return votedFor;
}

Just an example, don't know if I got the meaning of your `vote` boolean right to indicate an up/down vote.

Problem

I am doing a simple Poll system. I have 2 tables: `Person`: ID, Name, Surname `Vote`: ID, Vote (Boolean), VoterID (This is actually `FK_PersonID`), PersonID (This is actually `FK_PersonID` as well). I need to be able to identify who cast the vote as well as who the vote was for - using the people stored in the `Person` table for both of these needs. The table `Person` contains user details of people that can "Vote" as well as be "Voted for". People are allowed to decide whether they want to vote for themselves or not. I've mapped out my tables in my `domain` objects like this: Person ``` private Integer ID; private String name; private String surname; @Id @GeneratedValue(strategy = GenerationType.AUTO) @Column(name = "ID") public Integer getID() { return ID; } public void setID(Integer ID) { this.ID = ID; } @Column(name = "name") public String getName() { return name; } public void setName(String name) { this.name = name; } @Column(name = "surname") public String getSurname() { return surname; } public void setSurname(String surname) { this.surname = surname; } ``` Vote ``` private Integer ID; private Person voter; private Person person; private Boolean vote; @Id @GeneratedValue(strategy = GenerationType.AUTO) @Column(name = "ID") public Integer getID() { return ID; } public void setID(Integer ID) { this.ID = ID; } @Column(name = "vote") public Boolean getVote() { return vote; } public void setVote(Boolean vote) { this.vote = vote; } @ManyToOne @JoinColumn(name = "personID") public Person getVoter() { return voter; } public void setVoter(Person voter) { this.voter = voter; } @ManyToOne @JoinColumn(name = "personID") public Person getPerson() { return person; } public void setPerson(Person person) { this.person = person; } ``` Error message Caused by: org.hibernate.MappingException: Repeated column in mapping for entity: web.poll.domain.Vote column: personID (should be mapped with insert="false" update="false")

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