Springboot JPA entity is auto loading lazy join entities

Question

I have an entity as

    @Getter
    @Setter
    @Entity
    @Table(name = "feature")
    @JsonIgnoreProperties({"hibernateLazyInitializer", "handler"})
    public class Feature {

        @Id
        @GeneratedValue(strategy = GenerationType.IDENTITY)
        private Integer id;

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

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

        @OneToMany(mappedBy = "featureId", fetch = FetchType.LAZY)
        private transient Collection<FeatureComponent> components;
}

While in its Repository(Dao) file, I have

public interface FeatureDao extends JpaRepository<Feature, Integer> {

    @Query("SELECT e FROM Feature e")
    public List<Feature> getAll();

    @Query("SELECT e FROM Feature e LEFT JOIN e.components fc WHERE e.id= :id")
    public Feature getWithDetail(@Param("id") Integer id);
}

When I'm calling featureDao.getAll(); it returns all features but including components list filled and because of that, my response it being too large to load on client-side.

I'm unable to understand why it is happening when I'm using Lazy fetch mode and didn't mentioned joining with components in my getAll method.

Please help to resolve that issue, Thanks in advance.

@Mansoor, Actually I have to add a where clause with a sub query... to avoid complexity in question, I skipped that part... — M.Haris Qayyum
– M.Haris Qayyum, Commented Sep 27, 2021 at 16:59
My guess would be stackoverflow.com/a/21749892/1225328, i.e. Jackson triggering the unwanted queries to FeatureComponent when seralising your List<Feature> since it finds a getter for components. — sp00m
– sp00m, Commented Sep 27, 2021 at 17:18
But I don't want to avoid that 'components' because I need them for other purposes (that you can check in my other query i.e. getWithDetail)... I Know, We can easily ignore entity fields by @JsonIgnore annotation... — M.Haris Qayyum
– M.Haris Qayyum, Commented Sep 27, 2021 at 17:54

João Dias · Accepted Answer · 2021-09-27 18:53:00Z

Just like @spOOm already mentioned I also suspect this is the side effect of Jackson Feature entity serialization into JSON triggering the load of all the components.

That is why using DTOs instead of plain Entities is usually advisable when returning data via a Controller. With DTOs, you clearly define whatever you want to include in the response to the caller. You can even reorganize your model so that it fits better the needs of the clients. You decouple your inner model and the model your API consumers know, making it possible to rework your inner model and still keep the same public model. You could have the following DTO.

public class FeatureSimpleDto {
    private Integer id;
    private String name;
    private String description;
}

Then, in your Controller or Service (here you can find different opinions) you would basically convert your Feature entity into a FeatureSimpleDto that would be returned by your Controller. Here you can use mapping libraries such as MapStruct or you can do it on your own (I usually tend to prefer doing it on my own, one less dependency to rely on).

serob · Accepted Answer · 2021-09-27 19:43:36Z

0

Using Lombok may be a problem, depending on the relationship between tables, try to create getters manually in entity classes.

answered Sep 27, 2021 at 19:43

serob

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Comments

M.Haris Qayyum · Accepted Answer · 2021-09-28 07:16:54Z

0

Thanks to everyone for providing workarounds... But every work item requires lots of changes which were not possible for me...

Luckily I found a solution that is working fine for me... Better to post here...

Step-1: Add dependency in pom.xml file

<dependency>
    <groupId>com.fasterxml.jackson.datatype</groupId>
    <artifactId>jackson-datatype-hibernate5</artifactId>
</dependency>

Step-2: Add a 'Bean' for Hibernate Module

We can add bean in any file having @Configuration annotation... Even, we can add in Springboot main application file(where we have main method).

@Bean
public Module datatypeHibernateModule() {
    return new Hibernate5Module();
}

That's it, Happy Coding...

answered Sep 28, 2021 at 7:16

M.Haris Qayyum

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