java - Hibernate : Unknown column in field list

Question

I'am trying to do an unidirectional @OneTaMany relationship like in the Hibernate User Guide (2.7.2) but when I try to save the following object in a MariaDB Database:

Filter filter = new Filter("TLS_A320");
filter.addConstraint(new Constraint(ConstraintType.DEPARTURE, "TLS"));
filter.addConstraint(new Constraint(ConstraintType.AIRCRAFT, "A320"));
session.save(filter);

I got this exception :

com.mysql.jdbc.exceptions.jdbc4.MySQLSyntaxErrorException: Unknown column 'Filter_idFilter' in 'field list'

Here are the 2 classes:

Filter.java

public class Filter {

    @Id
    @Column(name = "idFilter")
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private int id;

    @Column(name = "name")
    private String name;

    @OneToMany(cascade = CascadeType.ALL, orphanRemoval = true)
    private List<Constraint> constraintList;

    //more code
};

Constraint.java

public class Constraint {

    @Id
    @Column(name = "idConstraint")
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private int id;

    @Column(name = "type")
    @Enumerated(EnumType.ORDINAL)
    private ConstraintType constraintType;

    @Column(name = "value")
    private String value;

    //more code
}

And here is the tables definition :

CREATE TABLE `Constraint` (
    idConstraint INT NOT NULL AUTO_INCREMENT,
    type INT NOT NULL,
    value VARCHAR(10) NOT NULL,

    PRIMARY KEY (idConstraint)
);

CREATE TABLE Filter (
    idFilter INT NOT NULL AUTO_INCREMENT,
    name VARCHAR(50) UNIQUE NOT NULL,

    PRIMARY KEY (idFilter)
);

CREATE TABLE Filter_Constraint (
    idFilter INT UNIQUE NOT NULL,
    idConstraint INT NOT NULL,

    CONSTRAINT fk_Filter_Constraint_Filter FOREIGN KEY (idFilter) REFERENCES Filter(idFilter),
    CONSTRAINT fk_Filter_Constraint_Constraint FOREIGN KEY (idConstraint) REFERENCES `Constraint`(idConstraint)
);

It seems to me that that Filter and Constraint insertions are fine and the exception happens when inserting in the Filter_Constraint table :

DEBUG org.hibernate.SQL - insert into Filter (name) values (?)
DEBUG org.hibernate.id.IdentifierGeneratorHelper - Natively generated identity: 4
DEBUG org.hibernate.SQL - insert into `Constraint` (type, value) values (?, ?)
DEBUG org.hibernate.id.IdentifierGeneratorHelper - Natively generated identity: 5
DEBUG org.hibernate.SQL - insert into `Constraint` (type, value) values (?, ?)
DEBUG org.hibernate.id.IdentifierGeneratorHelper - Natively generated identity: 6
DEBUG org.hibernate.SQL - insert into `Filter_Constraint` (Filter_idFilter, `constraintList_idConstraint`) values (?, ?)
DEBUG org.hibernate.engine.jdbc.spi.SqlExceptionHelper - could not execute statement [n/a]
DEBUG com.mysql.jdbc.exceptions.jdbc4.MySQLSyntaxErrorException: Unknown column 'Filter_idFilter' in 'field list'

I'am pretty new to Hibernate and I just can't figure out what I did wrong.

Answer 1

You didn't define any join column or inverse join column on constraintList, hence Hibernate will autogenerate column names which most probably results in the name Filter_idFilter.

The entity name will be part of the name since Constraints could have an id field with the same name, i.e. idFilter. Of course you know that isn't the case but Hibernate doesn't (or at least the column name generation code isn't that complex) and hence it has to assume that could be the case.

The same is true for join table names so you'll probably want to use @JoinTable along with the definition of join columns and inverse join columns on constraintList. However, since the relation is OneToMany anyways, why don't you add a back reference to Constraint, add the filter's id to table Constraint and get rid of the join table entirely?