Serializing fails when @JsonView and @JsonFormat attributes are present [DATAREST-759]

Florin Duroiu opened DATAREST-759 and commented

There's a wicked issue I'm facing: I have the following domain class backed by a RDBMS table (postgresql). Using jackson-databind 2.6.4 and spring-data-rest-webmvc 2.4.2.RELEASE

@Getter @Setter
@Entity(name="ACCOUNT")
public class User extends ResourceSupport {
   @Id @GeneratedValue(strategy = GenerationType.IDENTITY)
   private Long id;

//more properties here

    @ManyToOne(optional = false)
    @JoinColumn(name = "account_state")
    @JsonView(UserView.AdminVisible.class)
    private AccountState accountState;

    @LastModifiedDate
    @JsonFormat(shape = JsonFormat.Shape.STRING, pattern = "yyyy-MM-dd\'T\'HH:mm:ss\'Z\'", timezone = "UTC")
    @JsonProperty(access = JsonProperty.Access.READ_ONLY)
    private Date updatedAt;

    @CreatedDate
    @JsonFormat(shape = JsonFormat.Shape.STRING, pattern = "yyyy-MM-dd\'T\'HH:mm:ss\'Z\'", timezone = "UTC")
    @JsonProperty(access = JsonProperty.Access.READ_ONLY)
    Date createdAt;
}

AccountState is yet another entity that is backed by a separate table.

I have a controller that has @JsonView(UserView.UserVisible.class) annotated methods where the accountState field is not exposed. I use spring.jackson.mapper.default-view-inclusion=true
to avoid annotating each field with @JsonView(...UserVisible.class).
I am also exposing a UserRepository extends PagingAndSortingRepository<User, Long> repo (for admin access). Here there is no @JsonView filtering applied and normally all attributes should be exposed.

The problem I'm facing is that when I create (or retrieve an existing) entity via the UserRepository CRUD interface, I get the following exception:

Could not write content: java.sql.Timestamp cannot be cast to java.lang.String

After investigating the cause, I found the found the following:
PersistentEntityJackson2Module.updateBuilder filters-out the accountState since it is isLinkableAssociation.
This causes BeanSerializerBase to have different _props and _filteredProps arrays, with _filteredProps being one element less than _props
In turn, this causes the following code in BeanSerializerBase.resolve to set the wrong serializer to the wrong property since the _props and _filteredProps arrays don't match:

// and maybe replace filtered property too? (see [JACKSON-364])
if (i < filteredCount) {
    BeanPropertyWriter w2 = _filteredProps[i];
    if (w2 != null) {
        w2.assignSerializer(ser);
    }
}

To fix this behaviour one has to literally relocate the accountState attribute (the one that resolves to linkable association) at the bottom of the domain class. This way, even if the _props and _filteredProps don't match, the first n-1 elements will match and thus the serialization will succeed.

Some more info:

• The same behaviour happens when having an @Id field due to the same logic in PersistentEntityJackson2Module.updateBuilder.
• Adding explicit @JsonSerializer for attributes is also a workaround this issue due to "if(prop.hasSerializer()) {continue;} " bit in BeanSerializerBase.resolve that skips the problematic code above altogether.

Any help in the matter is appreciated. In the mean time I'm applying the fix above

Affects: 2.4.2 (Gosling SR2)