I use datanucleus and MongoDB for storing my objects. I detected problems with the lazy loading.
One on My class is :
public class Member implements Serializable{
private static final long serialVersionUID = 1L;
#PrimaryKey
#Persistent(defaultFetchGroup = "true", valueStrategy = IdGeneratorStrategy.IDENTITY)
private String key;
private String username;
#Persistent(defaultFetchGroup="true",dependent="true")
private Parameter param = null;
}
And the code for retrieving this object is :
Transaction tx = pm.currentTransaction();
tx.begin();
Member member = pm.getObjectById(Member.class,"MyID");
tx.commit();
//if I check here, the field "param" is null.
When I check, the field "param" is null. However, I set the meta data to load by default the param. Maybe the driver MongoDB-JDO doesn't support the metadata "defaultFetchGroup".
Could you tell me what happens?
Thanks a lot.
What the situation is "here" (outside the transaction) depends totally on the object lifecycle and what persistence options you have enabled. That link defines it. Likely the object is HOLLOW, so fields have been unloaded and you didnt set "datanucleus.RetainValues"
Related
I would like to use hibernate search's #IndexingDependency with a PropertyBridge but I can't seem to make it work.
I get this error :
Hibernate ORM mapping: type 'com.something.Person': path '.currentStatus':
failures:
- HSEARCH700020: Unable to find the inverse side of the association on type
'com.something.Person' at path '.currentStatus<no value extractors>'. Hibernate Search
needs this information in order to reindex 'com.something.Person' when
'com.something.Status' is modified. You can solve this error by defining the inverse
side of this association, either with annotations specific to your integration
(#OneToMany(mappedBy = ...) in Hibernate ORM) or with the Hibernate Search
#AssociationInverseSide annotation. Alternatively, if you do not need to reindex
'com.something.Person' when 'com.something.Status' is modified, you can disable
automatic reindexing with #IndexingDependency(reindexOnUpdate = ReindexOnUpdate.SHALLOW)
Not sure if I'm doing something wrong or if what I'm trying to do isn't possible. Thank for the help.
Here are the files involved.
Person.class
#Entity
#Table
#Indexed
public class Person {
#OneToMany(mappedBy = "patient", cascade = CascadeType.ALL)
private Set<Status> status = new HashSet<>();
#Transient
#StatusBinding(fieldName = "currentStatus")
#IndexingDependency(derivedFrom = #ObjectPath(#PropertyValue(propertyName = "status")))
public Status getCurrentStatus() {
return this.status.stream()
.filter(it -> it.getDate().isAfter(LocalDate.now()))
.max(Comparator.comparing(Status::getDate))
.orElse(null);
}
}
StatusBinding.class
#Retention(RetentionPolicy.RUNTIME)
#Target({ElementType.METHOD, ElementType.FIELD})
#PropertyMapping(processor = #PropertyMappingAnnotationProcessorRef(type = StatusBinding.Processor.class))
#Documented
public #interface StatusBinding {
String fieldName() default "";
class Processor implements PropertyMappingAnnotationProcessor<StatusBinding> {
#Override
public void process(PropertyMappingStep mapping, StatusBindingannotation, PropertyMappingAnnotationProcessorContext context) {
StatusBinderbinder = new StatusBinder();
if (!annotation.fieldName().isBlank()) binder.setFieldName(annotation.fieldName());
mapping.binder(binder);
}
}
}
StatusBinder.class
public class StatusBinder implements PropertyBinder {
#Setter private String fieldName = "mainStatus";
#Override
public void bind(PropertyBindingContext context) {
context.dependencies()
.use("status")
.use("date")
.use("note");
IndexSchemaObjectField mainStatusField = context.indexSchemaElement().objectField(this.fieldName);
context.bridge(Status.class, new StatusBridge(
mainStatusField.toReference(),
mainStatusField.field("status", context.typeFactory().asString()).toReference(),
mainStatusField.field("date", context.typeFactory().asLocalDate()).toReference(),
mainStatusField.field("note", context.typeFactory().asString()).toReference()
));
}
private static class StatusBrige implements PropertyBridge<Status> {
private final IndexObjectFieldReference mainStatusField;
private final IndexFieldReference<String> statusField;
private final IndexFieldReference<LocalDate> dateField;
private final IndexFieldReference<String> noteField;
public StatusBrige(
IndexObjectFieldReference mainStatusField,
IndexFieldReference<String> statusField,
IndexFieldReference<LocalDate> dateField,
IndexFieldReference<String> noteField
) {
this.mainStatusField = mainStatusField;
this.statusField = statusField;
this.dateField = dateField;
this.noteField = noteField;
}
#Override
public void write(DocumentElement target, Status mainStatus, PropertyBridgeWriteContext context) {
DocumentElement statutElement = target.addObject(this.mainStatusField);
statutElement.addValue(this.statusField, mainStatus.getStatus);
statutElement.addValue(this.dateField, mainStatus.getDate());
statutElement.addValue(this.noteField, mainStatus.getNote());
}
}
}
Problem
When a Status entity is modified, Hibernate Search doesn't know how to retrieve the corresponding Person having that Status as its currentStatus.
Solution
Assuming the currentStatus is always contained in status, and since Status.patient is the inverse side of the Person.status association, you should only need to add this:
#Transient
#StatusBinding(fieldName = "currentStatus")
#IndexingDependency(derivedFrom = #ObjectPath(#PropertyValue(propertyName = "status")))
// ADD THIS ANNOTATION
#AssociationInverseSide(
inversePath = #ObjectPath(#PropertyValue(propertyName = "patient"))
)
public Status getCurrentStatus() {
// ...
}
Why?
I'll try to explain this, but it's a bit complex, so bear with me.
Derived properties and the inverse side of associations are related concepts: they share the common purpose of allowing Hibernate Search to perform automatic reindexing.
However, they are still separate concepts, and Hibernate Search is not able to infer one from the other.
With #IndexingDependency(derivedFrom), you are defining what the computation of currentStatus depends on:
#IndexingDependency(derivedFrom = #ObjectPath(#PropertyValue(propertyName = "status")))
public Status getCurrentStatus() {
This tells Hibernate Search that currentStatus will change whenever the status property changes. With that information, Hibernate Search is able to determine that whenever you call person.getStatus().remove(...) or person.getStatus().add(...) (for example), your Person entity needs reindexing, because currentStatus is indexed, and it probably changed.
In your custom binder, you're also defining dependencies:
context.dependencies()
.use("status")
.use("date")
.use("note");
This tells Hibernate Search that whenever the status, date, and note properties of a Status entity change, the Person having that Status as its currentStatus will need reindexing.
However... what Hibernate Search doesn't know is how to retrieve the person having that Status as its currentStatus.
It may know how to retrieve all persons having that Status in their status set, but that's a different thing, isn't it? Hibernate Search doesn't know that currentStatus is actually one of the elements contained in the status property. For all it knows, getCurrentStatus() could very well be doing this: status.iterator().next().getParentStatus(). Then the current status wouldn't be included in Person#status, and it's unclear if myStatus.getPatient() could return a Person whose currentStatus is myStatus.
So you need to tell Hibernate Search explicitly: "from a given Status myStatus, if you retrieve the value of myStatus.getPatient(), you get the Person whose currentStatus property may point back to myStatus". That's exactly what #AssociationInverseSide is for.
Here is my entity class:
public class User {
#Id
UserIdentifier userIdentifier;
String name;
}
public class UserIdentifier {
String ssn;
String id;
}
Here is what I am trying to do:
public interface UserRepository extends MongoRepository<User, UserIdentifier>
{
User findBySsn(String ssn);
}
I get an exception message (runtime) saying:
No property ssn found on User!
How can I implement/declare such a query?
According to Spring Data Repositories reference:
Property expressions can refer only to a direct property of the managed entity, as shown in the preceding example. At query creation time you already make sure that the parsed property is a property of the managed domain class. However, you can also define constraints by traversing nested properties.
So, instead of
User findBySsn(String ssn);
the following worked (in my example):
User findByUserIdentifierSsn(String ssn);
I am using spring data's elastic search module, but I am having troubles building a query. It is a very easy query though.
My document looks as follows:
#Document(indexName = "triber-sensor", type = "event")
public class EventDocument implements Event {
#Id
private String id;
#Field(type = FieldType.String)
private EventMode eventMode;
#Field(type = FieldType.String)
private EventSubject eventSubject;
#Field(type = FieldType.String)
private String eventId;
#Field(type = FieldType.Date)
private Date creationDate;
}
And the spring data repository looks like:
public interface EventJpaRepository extends ElasticsearchRepository<EventDocument, String> {
List<EventDocument> findAllOrderByCreationDateDesc(Pageable pageable);
}
So I am trying to get all events ordered by creationDate with the newest event first. However when I run the code I get an exception (also in STS):
Caused by: org.springframework.data.mapping.PropertyReferenceException: No property desc found for type Date! Traversed path: EventDocument.creationDate.
So it seems that it is not picking up the 'OrderBy' part? However a query with a findBy clause (eg findByCreationDateOrderByCreationDateDesc) seems to be okay. Also a findAll without ordering works.
Does this mean that the elastic search module of spring data doesn't allow findAll with ordering?
Try adding By to method name:
findAllByOrderByCreationDateDesc
We're creating RESTFul API based on Play framework 2.1.x which transfers/accepts data in JSON format. Create, read and delete operations were easy to implement but we've got stuck with update operation.
Here are the entities we have:
Event:
#Entity
public class Event extends Model {
#Id
public Long id;
#NotEmpty
public String title;
#OneToOne(cascade = CascadeType.ALL)
public Location location;
#OneToMany(cascade = CascadeType.ALL)
public List<Stage> stages = new LinkedList<Stage>();
...
}
Location:
#Entity
public class Location extends Model {
#Id
public Long id;
#NotEmpty
public String title;
public String address;
...
}
Stage:
#Entity
public class Stage extends Model {
#Id
public Long id;
#NotEmpty
public String title;
public int capacity;
...
}
In our router we have following entry:
PUT /events/:id controllers.Event.updateEvent(id: Long)
updateEvent method in controller looks following way (note: we use Jackson library to map objects to JSON and back):
#BodyParser.Of(BodyParser.Json.class)
public static Result updateEvent(Long id) {
Event event = Event.find.byId(id);
Http.RequestBody requestBody = request().body();
JsonNode jsonNode = requestBody.asJson();
try {
ObjectMapper mapper = new ObjectMapper();
ObjectReader reader = mapper.readerForUpdating(event);
event = reader.readValue(jsonNode);
event.save();
} catch (IOException e) {
e.printStackTrace();
}
return ok();
}
After we've got Event from database, updated its values by reading from JSON with ObjectReader we try to save updated Event and get exception (similar one we get when trying to update list of Stages):
org.h2.jdbc.JdbcSQLException: Unique index or primary key violation: "PRIMARY_KEY_9F ON PUBLIC.LOCATION(ID)"; SQL statement: insert into location (id, title, address) values (?,?,?) [23505-168]
According to H2 logs framework tries to perform insert operation for location and fails as location with specified id already exists. We've investigated further ant it looks like when we get Event from DB, location is not joined because of lazy fetch. Looks like the problem occurs with saving other entities which our Event has relationships with. We've tried to force fetch operation for location by doing following:
Event event = Ebean.find(Event.class).fetch("location").where().eq("id", id).findUnique();
but still when we update this event with ObjectReader's readValue method and save Event we get the same exception.
We've also tried to create separate Event object from JSON and update Event from DB field by field (implemented merge operation by ourselves) and it worked but it looks odd that framework doesn't provide any means of merging and updating entities with data passed from client.
Could someone advise on how to solve this problem ? Any example showing how to implement merge of entity with JSON data coming from client and updating it in storage would be highly appreciated.
You've probably already fixed the error by now, but in case this helps someone else, I'm answering it anyway.
I'm just a beginner with Play Framework as well, only started a few days ago. But I believe when you have in your code:
event.save();
you should be doing instead:
event.update();
The problem here is that you're not inserting a new entity into the database, but in fact just updating the one already there, so you need to use the second method.
You can find more info about this at http://www.playframework.com/documentation/2.0/api/java/play/db/ebean/Model.html
I have two entities. "Price" class has "CalculableValue" stored as SortedMap field.
In order to support sorted map I wrote customizer. After that, it seems #CascadeOnDelete is not working. If I remove CalculableValue instance from map and then save "Price" EclipseLink only updates priceId column to NULL in calculableValues table...
I really want to keep the SortedMap. It helps to avoid lots of routine work for values access on Java level.
Also, there is no back-reference (ManyToOne) defined in the CalculableValue class, it will never be required for application logic, so, wanted to keep it just one way.
Any ideas what is the best way to resolve this issue? I actually have lots of other dependencies like this and pretty much everything is OneToMany relation with values stored in sorted map.
Price.java:
#Entity
#Table(uniqueConstraints={
#UniqueConstraint(columnNames={"symbol", "datestring", "timestring"})
})
#Customizer(CustomDescriptorCustomizer.class)
public class Price extends CommonWithDate
{
...
#CascadeOnDelete
#OneToMany(cascade = CascadeType.ALL, fetch = FetchType.EAGER)
#MapKeyColumn(name="key")
#JoinColumn(name = "priceId")
private Map<String, CalculatedValue> calculatedValues =
new TreeMap<String, CalculatedValue>();
...
}
public class CustomDescriptorCustomizer implements DescriptorCustomizer
{
#Override
public void customize(ClassDescriptor descriptor) throws Exception
{
DatabaseMapping jpaMapping = descriptor.getMappingByAttribute("calculatedValues");
((ContainerMapping) mapping).useMapClass(TreeMap.class, methodName);
}
}
Your customizer should have no affect on this. It could be because you are using a #JoinColumn instead of using a mappedBy which should normally be used in a #OneToMany.
You can check the mapping in your customizer using, isCascadeOnDeleteSetOnDatabase()
or set it using
mapping.setIsCascadeOnDeleteSetOnDatabase(true)