与JoinTable的单向OneToMany关系-未生成表

Question

I tried to create an unidirectional OneToMany relation with a JoinTable in Play Framework 2.1. However, the framework is not generating the 'JoinTable': "transformation_input_files". The strange part is that if I change the relation to ManyToMany the table is generated. Here is the code:

So its about an Transformation class containing multiple S3Files. Here is the Transformation file:

@Entity
@Table(name = "transformations")
public class Transformation extends Model {

    @Id
    public Long id;

    /*...*/

    @OneToMany(cascade = CascadeType.PERSIST)
    @JoinTable(
        name="transformation_input_files",
        joinColumns = @JoinColumn( name="transformation_id"),
        inverseJoinColumns = @JoinColumn( name="input_file_id")
    )
    public List<S3File> inputFiles;
}

Here is the S3File:

@Entity
@Table(name="s3files")
public class S3File extends Model {

    @Id
    public Long id;

    /*...*/
}

The S3Files are used in more models, so that can not be a bidirectional relation. If I change @OneToMany in @ManyToMany it does generate the join table, however, I do like to stick with the @OneToMany relation.

How do I solve this problem? Did I missed something?

Answer 1

In one-to-many relationship you have to store the relation in "Many" entity..if you don't want to store the value in the S3File class you have to create another class to join the two classes.

Example:
@Entity
@Table(name="transformations_ s3files")
public class Relation extends Model {
    @Id
    public Long id;

    @ManyToOne
    public Transformation transformation;        

    @OneToOne
    public S3File file;
}