Michael Darsow

Hello there,

i am preparing for the OCEJPA certification exam and i want to take it soon. The prerequirement for the OCEJPA exam is a java programmer certification. I have made such a certification successfully. But i wonder how it is checked that i have this certificate. Do i need to take the paper to the testing center when i take the OCEJPA exam? Or would i not be able to register online when would not have such a certificate?

Thanks!

Hi there,

i would like to combine different inheritance strategies from JPA, but somehow i don't get it to work.

My class hierarchy is like this:
A
-B
-C
--D
--E

I have a database Table for A, B and C. The Table for class A actually only contains the ID, so that other tables can refer to it.
So i have a JOINED inheritance strategy for the inheritance from A to B and C. The data of D and E should all go into the table of C.

Could anyone help me and tell me how i could realize this please?

My class definitions and annotations are like this, but jpa throws an exception which tells me that class C is not allowed to add an extra column.
I am using OpenJPA.

@Entity @Inheritance(strategy=InheritanceType.JOINED) @DiscriminatorColumn(name="TYPE") public abstract class A implements Serializable {...} @Entity @PrimaryKeyJoinColumn(name="ID", referencedColumnName="ID") @DiscriminatorValue("B") public class B extends A implements Serializable {...} @Entity @PrimaryKeyJoinColumn(name="ID", referencedColumnName="ID") @DiscriminatorValue("C") @Inheritance(strategy=InheritanceType.SINGLE_TABLE) @DiscriminatorColumn(name="MY_TYPE") public abstract class C extends A implements Serializable {...} @Entity @PrimaryKeyJoinColumn(name="ID", referencedColumnName="ID") @DiscriminatorValue("D") public class D extends C implements Serializable {...}


Thanks a lot!

Hi there,

i am pretty new to JSF and i am trying to display a formular which has a date-field to be filled by the user.

In my JSF-Page i am iterating over a list objects A, which has 3 String fields and 1 Date field.

<h:form id="form"> <ui:repeat var="obj" value="#{myBackingBean.objectList}"> <h:inputText value="#{obj.field1}"></h:inputText> <br/> <h:inputText value="#{obj.field2}"></h:inputText> <br/> <h:inputText value="#{obj.field3}"></h:inputText> <br/> <h:inputText value="#{obj.date}"> <f:convertDateTime pattern="dd-MM-yyy"/> </h:inputText> <br/> <br/> </ui:repeat> <h:commandButton value="Submit" actionListener="#{myBackingBean.buttonAction}"/> </h:form>

When the Submit-Button is pressed, a red error-message appears on the screen. Instead I would like to display a popup with an errormessage when the user presses the submit-Button and the date-conversion fails.

Is there a way to achieve this?
Thank you in advance

Hi there!

I am new to this forum. Found this forum while looking for a solution for my problem. It looks very cool!

I need your help. I am doing JPA (eclipselink) since some weeks and i am wondering if there is a way to optimize my code.
Simplified i need to copy 500-1000 records from one database to another when the user presses on a button.

I have the entities A and B where A has a list of B.

So when the user starts the copying i load all B's from A with

List<B> listOfB = a.getB(); // a has about 500-1000 B's

and then i iterate over the list and persist each B.

for (B b : listOfB) { entityManager.persist(b); }

This takes about 2-3 seconds for 500-1000 records. (just guessed the time, did not measure it)

My question is how this can be optimized?

The first thing i have in mind is the caching.
The caching is active, but i do not need all these records to get into the cache.
Is it possible to bypass the cache for loading and persisting these records?

And if there are more ways to optimize the process i would be very happy if you can help me out!

Thanks!