Traversing ORM relationships returns duplicate results

I have 4 tables -- store, catalog_galleries, catalog_images, and catalog_financials.

When I traverse the relationship from store --> catalog_galleries --> catalog_images in other words: store.getCatalogGallery().getCatalogImages() I get duplicate records. Does anyone know what could be the cause of this? Any suggestions on where to look?

The store table has a OneToOne relationship with catalog_galleries which in turn has a OneToMany relationship with catalog_images and an eager fetch type. The store table also has a OneToMany relationship with catalog_financials.

Below are the relevant entities:

Store entity

@Entity
@Table(name="store")  
public class Store {
    ...
    private CatalogGallery gallery;
    ...
    @OneToOne(mappedBy="store")
    public CatalogGallery getGallery() {
        return gallery;
    }
}

CatalogGallery entity

@Entity
@Table(name="catalog_galleries")  
public class CatalogGallery {
    ...
    private Store store;
    private Collection<CatalogImage> catalogImages;
    ...
    @OneToOne
    @PrimaryKeyJoinColumn
    public Store getStore() {
        return store;
    }

    @OneToMany(mappedBy="catalogGallery", fetch=FetchType.EAGER)
    public Collection<CatalogImage> getCatalogImages {
        return catalogImages;
    }
}

CatalogImage entity

@Entity
@Table(name="catalog_images")  
public class CatalogImage {
    ...
    private 开发者_如何学运维CatalogGallery catalogGallery;
    ...
    @ManyToOne
    @JoinColumn(name="gallery_id", insertable=false, updatable=false)
    public CatalogGallery getCatalogGallery() {
        return catalogGallery;
    }

}

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This is because of your fetch = FetchType.EAGER.
Hibernate creates JOINs and tries to get all your collections with one query.
If you really need FetchType.EAGER and don't want to replace your collection with Set you can use @Fetch (FetchMode.SELECT) annotation for your collection:

@OneToMany(mappedBy="catalogGallery", fetch=FetchType.EAGER)
@Fetch (FetchMode.SELECT)
public Collection<CatalogImage> getCatalogImages {
    return catalogImages;
}

For more information see this post

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If you implement the equals and hashcode methods correctly and store in a Set rather than a Collection, it is less of an issue unless the volume of duplicates is excessive.

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1. Your getter catalogImages() does not follow Java Bean naming convention. I'm not sure, but it might confuse JPA provider somehow.
2. By using Collection<CatalogImage> you've explicitly told JPA provider that duplicates are allowed. As it was already told, using Set instead of Collection solves duplicates-issue in most cases and allows avoiding FetchType.EAGER unless you really need it.