CODEWITHSUNDEEP
google-app-enginejpa
friedkiwi
friedkiwi

Reputation: 2198

Google App Egine JPA: how to fetch a object with specific parameters

I've got the object User with the following attributes: Id(long), Name(string), e-mail(string), activated(bool). I added all the correct annotations.

Now is my question, how do I use the EntityManager to fetch a specific object if only the name is known?

I know that I can use the find method to find an object with a specific Id. But how do I use it for fetching an object with the name property set to "Use R Name" for example.

Thank you!

Yvan

Upvotes: 0

Views: 175

Answers (1)

JB Nizet
JB Nizet

Reputation: 691765

As in any JPA application, you use JPA queries. See http://download.oracle.com/javaee/5/tutorial/doc/bnbqw.html#bnbrg for an introduction on queries and JPQL.

In your case, the code would look like this : 

public List<User> findUsersByName(String name) {
    List<User> users = entityManager.createQuery(
        "SELECT u FROM User u WHERE u.name = :userName")
        .setParameter("userName", name)
        .getResultList();
    return users;
}

Note that everything supported by JPA is not supported in Google App Engine : see http://code.google.com/intl/fr/appengine/docs/java/datastore/jpa/overview.html#Unsupported_Features_of_JPA for details.

Upvotes: 1

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