I don't know why I can't persistent MAP in JPA in GAE
AnnualReport thatyear = .......
if (stud.getAnnualReport() == null){
Map<Integer,AnnualReport> temp = new HashMap<Integer,AnnualReport>();
temp.put(thatyear.getAttrKey(), thatyear);
stud.setAnnualReport(temp);
} else{
Map<Integer,AnnualReport> temp2 = stud.getAnnualReport();
temp2.put(thatyear.getAttrKey(), thatyear);
stud.setAnnualReport(temp2);
}
em.getTransaction().begin();
try {
em.persist(stud);
em.getTransaction().commit();
} finally {
if (em.getTransaction().isActive()) {
em.getTransaction().rollback();
}
}
Actually in http:// localhost :8888/_ah/admin/datastore I can see the thatyear has been persistent; However, I can never get them; or, stud.getAnnualReport() is always empty.
EntityManager em;
em = EMF.get().createEntityManager();
AnnualReport thatyear = stud.getAnnualReport().get(yearselected);
I really don't know what to do. Following is the relationship between Stud & AnnualReport
Stud
#Entity( name = "Stud")
public class Stud{
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
private Key studID;
private String lastName = new String();
private Map<Integer,AnnualReport>annualReport = new HashMap<Integer,AnnualReport>(20);
#OneToMany(mappedBy="stud",cascade = CascadeType.ALL)
#MapKey(name = "attrKey")
#Basic
public Map<Integer, AnnualReport> getAnnualReport() {
return annualReport;
}
AnnualReport
#Entity( name = "AnnualReport")
public class AnnualReport implements Serializable{
private static final long serialVersionUID = 3581307841164176872L;
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
private Key annualReportID;
public int attrKey;
#ManyToOne
Stud stud;
private String attendSchoolNote;
I don't know what happens. Why I can't get those map information which are already persistent?
No idea why you don't get the expected result, but then you present no debug info. You can easily follow the persistence process using the log, telling you what is actually persisted into the GAE Entity objects. GAE has a (JDO) unit test at
http://code.google.com/p/datanucleus-appengine/source/browse/trunk/tests/com/google/appengine/datanucleus/jdo/JDOMapTest.java
which demonstrates correct behaviour (and since JDO/JPA is simply a wrapper over the persistence engine, no reason to think the same would not persist fine using JPA).
Edit : in fact I just added a test for JPA maps at http://code.google.com/p/datanucleus-appengine/source/browse/trunk/tests/com/google/appengine/datanucleus/jpa/JPAMapTest.java and works fine.
Related
I'm trying to create a Spring Boot backend for my project. In the database I have Deck and Word tables with a many-to-many relationship connected via DeckWord table. The bridge table has additional fields and a composite PK consisting of the other 2 tables' PK's.
I am not sure about how I should structure the crud operations in my project. Say I'm trying to add a new word and it should be assigned to a certain deck. What model's controller should handle the post operation in that scenario: Word or DeckWord? Should the Deck's List<DeckWord> be updated as well?
UPDATE:
Included the models, omitted the getters, setters and constructors
#Entity
#Table(name = "deck")
public class Deck {
#Id
#SequenceGenerator(
name = "deck_sequence",
sequenceName = "deck_sequence",
allocationSize = 1
)
#GeneratedValue(
strategy = GenerationType.SEQUENCE,
generator = "deck_sequence"
)
#Column(name = "deck_id")
private Long id;
#Transient
private Boolean learnt;
private String name;
#OneToMany(mappedBy = "deck", cascade = CascadeType.ALL)
private List<DeckWord> deckwords;
#ManyToOne
#JoinColumn(name="appuser_id",referencedColumnName="appuser_id")
private Appuser appuser;
}
and
#Entity
#Table(name = "word")
public class Word {
#Id
#SequenceGenerator(
name = "word_sequence",
sequenceName = "word_sequence",
allocationSize = 1
)
#GeneratedValue(
strategy = GenerationType.SEQUENCE,
generator = "word_sequence"
)
#Column(name = "word_id")
private Long id;
private String definition;
private String transcription;
#OneToMany(mappedBy = "word", cascade = CascadeType.ALL)
private List<DeckWord> deckwords;
}
and the bridge table:
#Embeddable
class DeckWordKey implements Serializable {
#Column(name = "deck_id")
Long deckId;
#Column(name = "word_id")
Long wordId;
}
#Entity
#Table
public class DeckWord {
#EmbeddedId
DeckWordKey id;
#ManyToOne
#MapsId("deckId")
#JoinColumn(name = "deck_id",referencedColumnName="deck_id")
Deck deck;
#ManyToOne
#MapsId("wordId")
#JoinColumn(name = "word_id",referencedColumnName="word_id")
Word word;
private Boolean learnt;
private LocalDate last_checked;
private WordGroup wordGroup;
}
Answering your questions:
What model's controller should handle the post operation in that scenario: Word or DeckWord?
Given that a Word should always be assigned to a Deck, then I would use a POST request to the URL "/decks/{deckId}/words" to create a new Word. The request body should include definition and transcription.
Should the Deck's List be updated as well?
Yes, it must. For that, you need to use deckId that you receive as a path parameter.
Can someone help me how should I join those three tables using JPA?
I already did 2 of 3 entities but please let me know if are ok:
#Entity
public class Pacienti {
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
private int id;
private String nume;
private String prenume;
//setters & getters
}
#Entity
public class Chestionare {
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
private int id;
#Id
#Column(name = "id_intrebare")
#GeneratedValue(strategy = GenerationType.AUTO)
private int idIntrebare;
private String intrebare;
//setters & getters
}
As I promise I come back after I'm generating entities automatically. Unfortunately now I have another problem.
Now I have the entity:
#Entity
#Table(name = "pacienti")
#NamedQuery(name = "Pacienti.findAll", query = "SELECT p FROM Pacienti p")
public class Pacienti implements Serializable {
private static final long serialVersionUID = 1L;
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
#Column(unique = true, nullable = false)
private int id;
#Column(nullable = false, length = 20)
private String nume;
#Column(nullable = false, length = 20)
private String prenume;
// bi-directional many-to-one association to Consultatii
#OneToMany(mappedBy = "pacienti")
private List<Consultatii> consultatiis;
// bi-directional many-to-one association to DetaliiPacient
#OneToMany(mappedBy = "pacienti")
private List<DetaliiPacient> detaliiPacients;
// bi-directional many-to-one association to Doctori
#ManyToOne(fetch = FetchType.LAZY)
#JoinColumn(name = "id_doctor", nullable = false)
private Doctori doctori;
// bi-directional many-to-one association to RaspunsChestionar
#OneToMany(mappedBy = "pacienti")
private List<RaspunsChestionar> raspunsChestionars;
public Pacienti() {
}
//setters and getters
}
But when I do :
Query queryResult = sessionFactory.getCurrentSession().createQuery("from Pacienti");
I'm getting:
Pacienti is not mapped [from Pacienti] Error.
Can someone tell me why? I also tried "pacienti is not mapped [from pacienti]" but same result
Thank you!
I would recommend you to use the jpa tools/plugins available with the IDEs which will auto generate these jpa entities for you using the database tables rather than manually creating these.
And they will take care of setting the relationship b/w different entities(db tables) in the auto generation process itself.
If you are Eclipse you can achieve this.
The problem is bcz there is no query with the name "from pacienti" in place of that pass the query name "Pacienti.findAll" in your createQuery method.
Plz let ne know once you try this, if you face any problem
I'm getting an exception after I added this embedded field in my entity:
#Entity
public class Team extends DataObject
{
#Embedded
private TeamEvolution teamEvolution = new TeamEvolution();
// NEW FIELD:
#Embedded
// #AttributeOverrides({ #AttributeOverride(name = "buffer", column = #Column) })
// #Enumerated
private ScoutBuffer scoutBuffer;
...
This guy is very simple:
#Embeddable
public class ScoutBuffer
{
private static final int BUFFER_SIZE = 150;
#Basic
private List<String> buffer;
... // from here on there are only methods...
When I try to merge my modifications I get the following exception:
java.lang.IllegalArgumentException: out of field index :-1
at com.olympya.futweb.datamodel.model.ScoutBuffer.jdoProvideField(ScoutBuffer.java)
at org.datanucleus.state.JDOStateManagerImpl.provideField(JDOStateManagerImpl.java:2585)
at org.datanucleus.state.JDOStateManagerImpl.provideField(JDOStateManagerImpl.java:2555)
at org.datanucleus.store.mapped.mapping.CollectionMapping.postUpdate(CollectionMapping.java:185)
at org.datanucleus.store.mapped.mapping.EmbeddedPCMapping.postUpdate(EmbeddedPCMapping.java:133)
// etc, etc...
I don't think there's anything to do, but I had to use JDOHelper.makeDirty before merging the entity for it to perceive that I modified scoutBuffer:
team.getScoutBuffer().add(playerIds);
JDOHelper.makeDirty(team, "scoutBuffer");
em.merge(team);
As you can see commented in the code, I tried the workaround described here, without success. Strange thing is that is from 2009... I'm using GAE 1.7.0, by the way. Also, I tried cleaning/re-enhancing the datamodel.
Using Play! framework and it's JPASupport class I have run into a problem with a legacy database.
I have the following class:
#Entity
#Table(name="product_catalog")
public class ProductCatalog extends JPASupport {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
public Integer product_catalog;
#OneToOne
#JoinColumn(name="upper_catalog")
public ProductCatalog upper_catalog;
public String name;
}
Some product catalogs don't have an upper catalog, and this is referenced as 0 in a legacy database. If I supply the upper_catalog as NULL, then expectedly JPA inserts a NULL value to that database column.
How could I force the null values to be 0 when writing to the database and the other way around when reading from the database?
I don't see any easy way of achieving what you want with JPA directly (and there are great chance that even if you find a way that works with basic operation like save or load, that it will not work with more complex use case, like complex criteria / hql, none standard fetching mode, etc)
So i would do that :
#Entity
#Table(name="product_catalog")
public class ProductCatalog extends JPASupport {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
public Integer product_catalog;
#Column(name="upper_catalog")
public Long upper_catalog_id;
public String name;
public ProductCatalog getUpperCatalog() {
if (upper_catalog_id == 0)
return null;
return ProductCatalog.findById(upper_catalog_id);
}
public void setUpperCatalog(ProductCatalog pc) {
if (pc == null) {
upper_catalog_id = 0;
}
else {
if (pc.id == null) {
// option 1. a bit like a cascade
pc.save();
// option 2. if you consider passing a transient entity is not valid
throw new RuntimeException("transient entity " + pc.toString());
}
upper_catalog_id = pc.id;
}
}
}
I see two options:
Use a primitive data type as Id (i.e. int instead of Integer)
If you are using Hibernate as JPA provider, use a CustomType to do the conversion
is it possible to use Constraints in the google-app-engine? It seems not to work ...
http://www.datanucleus.org/products/accessplatform_1_1/jpa/orm/constr...
The properties codingSystem and code should be unique. Is there a
workaround?
#Entity
#Table(uniqueConstraints = {
#UniqueConstraint(columnNames = { "codingSystem", "code" }) })
public class ArticleCode {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
private Key id;
private String codingSystem;
private String code;
Thanks,
Ralph
In a nutshell, no, they're not. The underlying datastore implementation doesn't support global transactions, so it's not practical to enforce arbitrary uniqueness constraints.
The workaround is to make the unique components part of the key name.
Thanks a lot, it works fine.
Here is my new code.
#Entity
public class ArticleCode {
#Id
private Key id;
#Column(name="codingSystem")
private String codingSystem;
#Column(name="code")
private String code;
public ArticleCode(Key parent, String codingSystem, String code) {
this.id = KeyFactory.createKey(parent, ArticleCode.class.getSimpleName(), codingSystem + code);
this.codingSystem = codingSystem;
this.code = code;
}