CODEWITHSUNDEEP
javaspringhibernate
Thanos M
Thanos M

Reputation: 673

Hibernate multiple @ManyToMany associations to the same entity

I have the following scenario:

I have an entity called MyOtherEntity that has a type attribute. MyEntity is associated only with certain MyOtherEntity entities based on the type of MyOtherEntity.

MyEntity class (only for demonstration it's not modelled correctly):

@Data
@Entity
@Table(name = "my_table")
public class MyEntity {

    @ManyToMany(fetch = FetchType.LAZY)
    @JoinTable(
        name = "my_entity_my_other_entity_type1",
        joinColumns = {@JoinColumn(name = "my_entity_id")},
        inverseJoinColumns = {@JoinColumn(name = "my_other_entity_id")}
    )
    private List<MyOtherEntity> myOtherEntityType1;

    @ManyToMany(fetch = FetchType.LAZY)
    @JoinTable(
        name = "my_entity_my_other_entity_type2",
        joinColumns = {@JoinColumn(name = "my_entity_id")},
        inverseJoinColumns = {@JoinColumn(name = "my_other_entity_id")}
    )
    private List<MyOtherEntity> myOtherEntityType2;

    // more fields
}

MyOtherEntity class:

@Data
@Entity
@Table(name = "my_other_entity")
public class MyOtherEntity {

    private String type;

    // more fields
}

A more detailed example:

Let's say there are only 3 types of MyOtherEntity type1, type2, and type3. My goal is to only associate MyEntity with MyOtherEntity entities of type1 and type2.

Is this functionality possible to achieve using Hibernate?

Upvotes: 0

Views: 131

Answers (1)

Akif Hadziabdic
Akif Hadziabdic

Reputation: 2890

You can use @Where annotation.

@Where(clause = "type = 'tyep1'")
@ManyToMany(fetch = FetchType.LAZY)
@JoinTable(
    name = "my_entity_my_other_entity_type1",
    joinColumns = {@JoinColumn(name = "my_entity_id")},
    inverseJoinColumns = {@JoinColumn(name = "my_other_entity_id")}
)
private List<MyOtherEntity> myOtherEntityType1;

@Where(clause = "type = 'tyep2'")
@ManyToMany(fetch = FetchType.LAZY)
@JoinTable(
    name = "my_entity_my_other_entity_type2",
    joinColumns = {@JoinColumn(name = "my_entity_id")},
    inverseJoinColumns = {@JoinColumn(name = "my_other_entity_id")}
)
private List<MyOtherEntity> myOtherEntityType2;

Upvotes: 1

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