NestedEntitySerializer fails to serialize Map for Hibernate proxy [DATAREST-897]

[spring-projects-issues]

Petar Tahchiev opened DATAREST-897 and commented

Hello,

I have the following JPA entity which I want to expose via rest:

@Entity
public class ProductEntity {


    @ElementCollection(targetClass = LobValue.class)
    @CollectionTable(name = "s_name_lv", joinColumns = @JoinColumn(name = "s_pk"))
    @MapKeyColumn(name = "locale")
    private Map<String, LobValue> s;
    
    //getters/setters

}

where the LobValue is an embeddable:

@Embeddable
@Access(AccessType.FIELD)
public class LobValue {

    private String s;

    public String getS() {
        return s;
    }

    public void setS(String s) {
        this.s = s;
    }
}

However when I try to access http://localhost:8080/rest/productEntities from the browser I get the following exception:

Caused by: org.hibernate.LazyInitializationException: failed to lazily initialize a collection, could not initialize proxy - no Session
	at org.hibernate.collection.internal.AbstractPersistentCollection.throwLazyInitializationException(AbstractPersistentCollection.java:579)
	at org.hibernate.collection.internal.AbstractPersistentCollection.withTemporarySessionIfNeeded(AbstractPersistentCollection.java:203)
	at org.hibernate.collection.internal.AbstractPersistentCollection.initialize(AbstractPersistentCollection.java:558)
	at org.hibernate.collection.internal.PersistentMap.put(PersistentMap.java:163)
	at org.springframework.data.rest.webmvc.json.PersistentEntityJackson2Module$NestedEntitySerializer.serialize(PersistentEntityJackson2Module.java:362)
	at com.fasterxml.jackson.databind.ser.BeanPropertyWriter.serializeAsField(BeanPropertyWriter.java:693)
	at com.fasterxml.jackson.databind.ser.std.BeanSerializerBase.serializeFields(BeanSerializerBase.java:690)
	... 140 more

which happens when the PersistentEntityJackson2Module tries to serialize the json.

This code works perfectly fine with Gosling-SR4 but the exception happens with Hopper or Ingals.

Here's a sample repository that reproduces this behavioud:

http://github.com/ptahchiev/demo-rest-problem

Just start the project with mvn spring-boot:run and then navigate to http://localhost:8080/rest/productEntities.

P.S. I mark this with blocker because it blocks me to update to Hopper or Ingalls

---

Referenced from: commits bacd8be, 759ba86

Backported to: 2.5.3 (Hopper SR3)

[spring-projects-issues]

Oliver Drotbohm commented

Should be an easy fix as this seems to related to Spring's CollectionFactory using the native Hibernate type which in turn requires an active Session.

Generally speaking, we use priorities to indicate severance regarding the overall functionality of the library. Otherwise every ticket would be filed as blocker

[spring-projects-issues]

Oliver Drotbohm commented

This should be fixed. You sample project (already set up to use snapshots) builds fine now

[spring-projects-issues]

Oliver Drotbohm commented

Please give the snapshots a try. Also, sample projects are most helpful if they're as small as possible and contain a failing test case and then we can just run the build to verify the fix. Having to issue particular requests manually is suboptimal as introduces a lot of other vectors that could potentially cause issues

[spring-projects-issues]

Petar Tahchiev commented

The latest SNAPSHOTs work fine. Thanks for the fix and the feedback - i'll try to create better sample projects from now on :)