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Questions tagged [entitymanager]

The EntityManager is the representation of a PersistenceContext, allowing a user to manipulate data pulled from a database.

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EntityManager refresh

I have web application using JPA. This entity manager keeps bunch of entites and suddenly I update the database from other side. I use MySQL and I use PhpMyAdmin and change some row. How to tell entity manager to re-synchronize, e.g. to forgot all…
zdenda.online
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How frequently should I create an EntityManager?

I have an EntityManagerFactory for which I can create one (or multiple) EntityManager instances. I'm using a Servlet environment, and I've got one EntityManagerFactory wired up to the servlet (via the servlet context) which is shared for the…
AlBlue
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How to manually start a transaction on a shared EntityManager in Spring?

I have a LocalContainerEntityManagerFactoryBean as EntityManager instance. To quickly drop a full tables' content, I want to run the following code: @Service public class DatabaseService { @Autowired private EntityManager em; …
membersound
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Spring + Hibernate + JPA

As of now I have a working Spring application with persistence. However now I want to use Hibernate with JPA to do all of my database activities. I want to do this using an entitymanager. I've been reading many documents and tutorials on this…
Albinoswordfish
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When should EntityManagerFactory instance be created/opened?

Ok, I read bunch of articles/examples how to write Entity Manager Factory in singleton. One of them easiest for me to understand a bit: http://javanotepad.blogspot.com/2007/05/jpa-entitymanagerfactory-in-web.html I learned that EntityManagerFactory…
Meow
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EntityManager refresh problem

I'm getting this error from my EntityManager when I call the refresh function. public void saveProduct(Product product) { entityManager.refresh(product); } I heard this could be a bug with Spring/Hibernate, however I'm not sure how to get…
Albinoswordfish
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Getting a reference to EntityManager in Java EE applications using CDI

I'm using Java EE 7. I would like to know what is the proper way to inject a JPA EntityManager into an application scoped CDI bean. You can't just inject it using @PersistanceContext annotation, because EntityManager instances are not thread safe.…
Flying Dumpling
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Query a MySQL db using java

Guys, simply put, I have a java application with a text output box. I'd like to query a Db and display the output into a text box. Example I have a Db with two columns food and color I'd like to : SELECT * in Table WHERE color = 'blue' Any…
Lexicon
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JAVA: an EntityManager object in a multithread environment

if I have multiple threads, each use injector to get the EntityManager object, each use the em object to select a list of other class objects. Ready to be used in a for loop. If a thread finishes first and calls clear(), will that affect the other…
user1589188
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What is the best way to update the entity in JPA

I am doing some CRUD operations using JPA. For updating an object which is the right way to do? Through update query or through the find method of EntityManager? I have one Employee object I need to update. Which is the right way? Please guide me.
user414967
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In Doctrine 2 can the Fetch Mode (Eager/Lazy etc.) be changed at runtime?

I have entities which I would like to eagerly load , and on other ocassions lazy (or even extra lazy) load. My mappings have no fetch mode declared in my YAML- so they use the default (lazy loading). Currently the only way to eagerly load is to by…
calumbrodie
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How to implement update () method in DAO using EntityManager (JPA)?

What is the standard way to implement simple update? Example: we have User with phone number NNNNNN and now we want to set it to YYYYYY. @PersistenceContext private EntityManager em; public void update (User transientUser) { what should be…
Roman
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Application vs Container Managed EntityManager

I am currently having a problem with understanding a concept of JPA. I am currently using/developing recent EclipseLink, Glassfish, Derby database to demonstrate a project. Before I develop something in much bigger picture, I need to be absolutely…
Hayati Guvence
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When we need more than one EntityManager?

I am learning JPA and have one question: In which situations we need more than one EntityManager in our application? The two situations that I am aware of are as follows: When our application is a multi-threaded application and more than one thread…
Yatendra
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Does Guice Persist provide transaction scoped or application managed EntityManager?

We use Guice Persist to inject EntityManager in our project. E.g. public class MyDao{ @Inject EntityManager em; public void someMethod(){ //uses em instance } } But it is unclear for us how injected instance of EntityManager is…
Piotr Sobczyk
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