Spring-Hibernate: Insertion error, not-null constraint (One-to-many relationship)

Question

I've been at this for a while and I can't find where I'm going wrong. I assume that it is some minor and/or simple error and a second pair of eyes will probably find it quickly.

I'm building a MySQL db consisting of Employees and Jobs. One Employee can have several Jobs, but a Job can only have a single Employee.

I used Liquibase to build my database. Here are my changesets:

<changeSet id="0001" author="mparker" context="base">
    <comment>Creating Base Table</comment>
    <createTable tableName="employees" >
        <column name="employeeID" autoIncrement="true" type="int">
            <constraints primaryKey="true" nullable="false"/>
        </column>
        <column name="firstname" type="varchar(50)">
            <constraints nullable="false"/>
        </column>
        <column name="lastname" type="varchar(50)">
            <constraints nullable="false"/>
        </column>
    </createTable>
</changeSet>
<changeSet id="0002" author="mparker">
    <createTable tableName="jobs" >
        <column name="jobID" autoIncrement="true" type="int">
            <constraints primaryKey="true" nullable="false"/>
        </column>
        <column name="employer" type="varchar(50)">
            <constraints nullable="false"/>
        </column>
        <column name="employeeID" type="int">
            <constraints nullable="false"/>
        </column>
    </createTable>
</changeSet>

As you can see, I am trying to create two tables where each entry has its own unique identifier that auto-increments when a new entry is added to the table. These columns should never be null, because the value should just be the previous value + 1.

Here are the relevant parts of the Employee and Job classes:

Employee.java:

@Entity
@Table(name = "employees")
public class Employee {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "employeeID")
    private Long id;

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

    @Column(name = "lastname")
    private String lastName;
    @OneToMany(mappedBy = "employee", cascade = CascadeType.PERSIST, fetch = FetchType.LAZY)
    private List<Job> jobList = new ArrayList<Job>();

    // getters and setters...
}

Job.java:

@Entity
@Table(name = "jobs")
public class Job {

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

    @ManyToOne(fetch = FetchType.LAZY, cascade = CascadeType.PERSIST)
    @JoinColumn(name = "employeeID")
    private Employee employee;

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

    // getters and setters...

}

And the method used to save an employee (using an autowired EntityManager):

public void saveEmployee(String firstname, String lastname, List<Job> jobs) {
    Employee employee1 = new Employee();
    employee1.setJobList(jobs);
    employee1.setFirstName(firstname);
    employee1.setLastName(lastname);
    entityManager.persist(employee1);
}

Here is the exception thrown when executing this method:

[ERROR] 2014-08-14 11:33:51,561 org.hibernate.engine.jdbc.spi.SqlExceptionHelper logExceptions - Column 'employeeID' cannot be null
[ERROR] 2014-08-14 11:33:51,603 com.sourceallies.webapp.exceptions.CustomHandlerExceptionResolver resolveException - could not execute statement; SQL [n/a]; constraint [null]; nested exception is org.hibernate.exception.ConstraintViolationException: could not execute statement

I'm at a loss as to what could be causing this. Shouldn't employeeID be generated upon each entry? Or did I mess something up with Hibernate?

Thanks!

@BranislavLazic You can look at the liquibase changesets to see what I'm going for. The db is completely empty right now because I'm getting this exception when trying to insert stuff into it. — Michael Parker, Aug 14 '14 at 17:01
got pointer from [here](http://stackoverflow.com/questions/4870863/why-jpa-persist-does-not-generated-auto-increment-primary-id) try using sequence generation type in your id field. — Vihar, Aug 14 '14 at 17:03
You misunderstood me, I asked how COLUMNS look like. Which datatypes they accept. I'm not asking whether some records are inserted or not. I'm not familiar with luquidbase. Does first snippet of xml code show how columns look like? — Branislav Lazic, Aug 14 '14 at 17:05
execute `desc employes` in your db and see if auto_increment is there. — bitkot, Aug 14 '14 at 17:49

score 1 · Accepted Answer · answered Aug 14 '14 at 19:15

Figured it out.

My save function should have assigned the employee I was creating to each job:

public void saveEmployee(String firstname, String lastname, List<Job> jobs) {
    Employee employee1 = new Employee();
    employee1.setFirstName(firstname);
    employee1.setLastName(lastname);
    for (Job job : jobs) {
        job.setEmployee(employee1);
    }
    employee1.setJobList(jobs);
    entityManager.persist(employee1);
}

I also needed to add a foreign key constraint to my employeeID column in my jobs table:

<changeSet id="0003" author="mparker">
    <addForeignKeyConstraint 
        baseTableName="jobs"
        baseColumnNames="employeeID"
        constraintName="FK_jobs_employeeID_employees_employeeID"
        referencedTableName="employees"
        referencedColumnNames="employeeID"/>
</changeSet>

Thanks for the suggestions, everyone.

Spring-Hibernate: Insertion error, not-null constraint (One-to-many relationship)

1 Answers1