To add to what Thomas said, if you use EntityManager#find(Class<T> entityClass, Object primaryKey), and the entity already exists in the current persistence context, your JPA implementation will not hit the db again (check the javadoc in javax.persistence.EntityManager). So, if you then use request scoped (or larger) entity managers, you will not see additional db hits when the default implementation of isLive() is called. However, if you create a JPAQL or HQL query in your Locator#find() method (and you don't override isLive() to do something else), it will hit the db again for each entity being serialized and sent to the client.
Jesse On Sun, Dec 11, 2011 at 10:52 AM, Thomas Broyer <[email protected]> wrote: > First, this has nothing to do with the Editor framework, but with > RequestFactory. > > If you're not using a Locator, or you're not overriding the isLive() > method of your Locator, then this is the expected behavior: this is how > RequestFactory determines whether an entity is still "alive" before sending > the response to the client. If it's not, then it'll tell the client that > the entity has been deleted (dispatch an EntityProxyChange event on the > EventBus with a WriteOperation.DELETED). The default implementation of > isLive(entity) is "find(entity.get()) != null", and this is also what > happens in the absence of a Locator for an entity (the difference is that > with a Locator you can override isLive() to change the default > implementation with, e.g., a more optimized one). > > -- > You received this message because you are subscribed to the Google Groups > "Google Web Toolkit" group. > To view this discussion on the web visit > https://groups.google.com/d/msg/google-web-toolkit/-/vV1wYZ6n9EUJ. > > To post to this group, send email to [email protected]. > To unsubscribe from this group, send email to > [email protected]. > For more options, visit this group at > http://groups.google.com/group/google-web-toolkit?hl=en. > -- You received this message because you are subscribed to the Google Groups "Google Web Toolkit" group. To post to this group, send email to [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/google-web-toolkit?hl=en.
