Skip to main content

Criteria query for a many to one relationship with join fetch 

CriteriaBuilder cb = _entityManager.getCriteriaBuilder();
CriteriaQuery<Message> criteriaQuery = cb.createQuery(Message.class);
Root<Message> messageRoot = criteriaQuery.from(Message.class);
Root<Device> deviceRoot = criteriaQuery.from(Device.class);

Fetch<Message, Device> recipientDeviceFetch = messageRoot.fetch("recipientDevice", JoinType.LEFT);
Join<Message, Device> messageRecipientDeviceJoin = (Join<Message, Device>) recipientDeviceFetch;

criteriaQuery.where(cb.and(messageRoot.get(Message.COLUMN_ID).in(messageIdsToDelete),
        cb.equal(deviceRoot.get(Device.COLUMN_PRIMARY_KEY), devicePrimaryKey)));
criteriaQuery.select(cb.construct(Message.class, messageRoot.get("recipientDevice"), messageRoot.get(Message.COLUMN_CLIENT_MESSAGE_ID)));

List<Message> messages = _entityManager.createQuery(criteriaQuery).getResultList();

return messages;

Comments

Post a Comment

Popular posts from this blog

Some good links

https://www.html5rocks.com/en/tutorials/internals/howbrowserswork/ http://taligarsiel.com/ClientSidePerformance.html -- Client side performance tips https://ariya.io/ https://vertx.io/docs/ -- New exciting Framework, Must read. https://javaee.github.io/ -- Very good resource to see various javaee projects and explore enterprise architecture and design concepts. https://projects.eclipse.org/projects/ee4j -- Lots of interesting open source projects by eclipse http://openjdk.java.net/projects/mlvm/ -- the main project for supporting more dynamic languages to jvm. http://esprima.org/ -- EcmaScript parser http://c2.com/ppr/ and http://hillside.net/ -- Good place to learn patterns http://cr.openjdk.java.net/~briangoetz/lambda/Defender%20Methods%20v4.pdf https://validator.w3.org/nu/ -- This will validate your website css and js https://www.cellstream.com/intranet/reference-reading/faq/216-what-is-2-128.html http://shattered.io/ -- An example of SHA1 collision attack.
1 comment
Read more

@MappedSuperclass vs. @Inheritance

MappedSuperClass must be used to inherit properties, associations, and methods. Entity inheritance must be used when you have an entity, and several sub-entities. You can tell if you need one or the other by answering this questions: is there some other entity in the model which could have an association with the base class? If yes, then the base class is in fact an entity, and you should use entity inheritance. If no, then the base class is in fact a class that contains attributes and methods that are common to several unrelated entities, and you should use a mapped superclass. For example: You can have several kinds of messages: SMS messages, email messages, or phone messages. And a person has a list of messages. You can also have a reminder linked to a message, regardless of the kind of message. In this case, Message is clearly an entity, and entity inheritance must be used. All your domain objects could have a creation date, modification date and ID, and you could thus
Post a Comment
Read more

Patterns Knowledge

Anti Pattern: Its a pattern which we repeatedly do and which brings negative results. Architecture by implication: Systems lacking a clear and document architecture. Cover Your Assets: Continuing to document and present alternatives, without ever making an architectural decision. Witches Brew: Architectures made by groups resulting in a mix of ideas and lack a clear vision. Gold Plating: Continuing to define an architecture well pass the time which results in no benefits to the architecture. Vendor King: A product dependent architectures leading to a loss of control of architecture and development costs Big Bang Architecture: Designing the entire architecture at the beginning of the project when you know the least about the system.
1 comment
Read more