CODEWITHSUNDEEP
javajpa
Riaz Bell
Riaz Bell

Reputation: 258

How to get old entity from entitymanager in JPA?

How to get old entity from entitymanager in JPA?

Code:

    Address address=em.find(Address.class,1);
    System.out.println("Name of Address: "+address.getAddressName);   // China
    address.setAddressName("Russia");
    Address address1=em.find(Address.class,address.getAddressId());
    System.out.println("Name of Address: "+address1.getAddressName); //?????????

How can I get my answer as "China"?

Upvotes: 2

Views: 1307

Answers (3)

Giridhar C R
Giridhar C R

Reputation: 180

em.refresh(address1)

should work as it refresh the objects state from database ("China") overwriting ("Russia") changes done to the object.

Variables address and address1 are reference to same object, so both address.getAddressName() and address1.getAddressName() returns "China".

Database still has old value until em.merge(address); em.flush(); is called.

Upvotes: 1

Gab
Gab

Reputation: 8332

DataNucleus is right, but I would advice to use a query with a query hint to bypass the cache instead of using a second instance of entityManager.

See http://wiki.eclipse.org/EclipseLink/UserGuide/JPA/Basic_JPA_Development/Caching/Query_Options

Upvotes: 2

DataNucleus
DataNucleus

Reputation: 15577

Use a different EntityManager. Any particular EntityManager will only ever return a single object with a particular identity (cached in the L1 cache)

Upvotes: 4

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