Google DataStore not storing child objects
-
13-09-2019 - |
Question
I have an entity Course that has a key to another entity (Document) inside.
@PersistenceCapable(identityType = IdentityType.APPLICATION, detachable="true")
public class Course{
@PrimaryKey
@Persistent(valueStrategy = IdGeneratorStrategy.IDENTITY)
private Key key;
@Persistent private Key document;
public Document getDocument() {
if (document != null)
return new DocumentServiceImpl().getDocumentById(document.getId());
return null;
}
public void setDocument(Document document) {
if (document != null)
this.document = new DocumentServiceImpl().saveAndGetKey(document);
}
In some test code I make a new Course entity, and assign a new Document entity, and the document entity is persisted when I set the document property on course. When I persist course, it will persist without error, however once it is persisted the document property will be null.
Any ideas? Here is my save function for course:
public Boolean save(Course c){
Boolean isSaved = false;
PersistenceManager pm = PMF.get().getPersistenceManager();
try{
pm.makePersistent(c);
isSaved = true;
}
catch(Exception e){
e.printStackTrace();
isSaved = false;
}
finally{
pm.close();
}
return isSaved;
}
Edit to add:
@PersistenceCapable(identityType = IdentityType.APPLICATION, detachable="true")
public class Document{
@PrimaryKey
@Persistent(valueStrategy = IdGeneratorStrategy.IDENTITY)
private Key key;
@Persistent private String data;
@Persistent private Set<Key> dTags;
@Persistent private Date dateCreated;
@Persistent private Date dateEdited;
public Document(){
this.dateCreated = new Date();
}
public Long getId() {
if (key == null){
return null;
} else {
return key.getId();
}
}
public void setId(Long id) {
if (id != null)
key = KeyFactory.createKey(this.getClass().getSimpleName(), id);
}
from DocumentServicesImpl:
public Key saveAndGetKey(Document d) {
try{
if (d.getKey() == null){
save(d);
}
return d.getKey();
} catch (Exception e){
return null;
}
}
public Boolean save(Document d) {
Boolean isSaved = false;
PersistenceManager pm = PMF.get().getPersistenceManager();
try {
pm.makePersistent(d);
isSaved = true;
} catch (Exception e) {
e.printStackTrace();
isSaved = false;
}finally{pm.close();}
return isSaved;
}
public Document getDocumentById(Long id) {
PersistenceManager pm = PMF.get().getPersistenceManager(); Document d = new Document();
try { d = pm.getObjectById(Document.class, id); } finally { pm.close(); }
return d; }
Solution
- What does the Document class look like?
- what does the DocumentServiceImpl class look like?
- What does your unit test for saveAndGetKey() look like? Does it check that the return value is a valid key? can you then look up that document in the datastore?
- Are your ServiceImpl classes PersistenceCapable, or PersistenceAware? I'm not sure if they need to be or not based just on what you've shown us.
New Troubleshooting Idea below: What happens if you try something simple like this: Just for now, make Course.document public. Then see if this simpler way of creating your entities works.
pm = yourPMfactory.getPersistenceManger();
Course c = new Course();
Document d = new Document();
c.document = d;
pm.makePersistent(c);
Key myKey = c.getKey();
Course c2 = (Course) pm.getObjectById(Course.class, myKey.getId());
assertTrue(c.document != null); //or however your favorite test suite does assertions.
pm.close();