EntitiesProviderServiceImpl.java

package com.dragome.examples.crudgrid.services.serverside;

import java.util.Arrays;
import java.util.List;

import javax.persistence.EntityManager;
import javax.persistence.EntityTransaction;
import javax.persistence.Persistence;
import javax.persistence.TypedQuery;
import javax.persistence.criteria.CriteriaBuilder;
import javax.persistence.criteria.CriteriaQuery;
import javax.persistence.criteria.Root;

import com.dragome.examples.crudgrid.model.Column;
import com.dragome.examples.crudgrid.model.ColumnImpl;
import com.dragome.examples.crudgrid.model.Identifiable;
import com.dragome.examples.crudgrid.model.People;
import com.dragome.examples.crudgrid.model.Place;
import com.dragome.examples.crudgrid.services.EntitiesProviderService;

public class EntitiesProviderServiceImpl implements EntitiesProviderService
{
	protected static EntityManager entityManager= Persistence.createEntityManagerFactory("hsqldb-ds").createEntityManager();

	public <T extends Identifiable> List<T> getAll(Class<T> entityType)
	{
		List<Place> resultList= findAll(Place.class);
		if (resultList.isEmpty())
			createPeople();

		return findAll(entityType);
	}

	public List<Column> getColumnsFor(Class<?> entityType)
	{
		if (entityType.equals(People.class))
			return Arrays.asList(new ColumnImpl("id", "col-md-1", true), new ColumnImpl("name", "col-md-2"), new ColumnImpl("place", "col-md-1", true, Place.class));
		else
			return Arrays.asList(new ColumnImpl("id", "col-md-1", true), new ColumnImpl("name", "col-md-2"));
	}

	private void createPeople()
	{
		EntityTransaction transaction= entityManager.getTransaction();
		transaction.begin();

		entityManager.persist(new People("Diego Maradona", new Place("Villa Fiorito, Buenos Aires, Argentina")));
		entityManager.persist(new People("Ariel Ortega", new Place("Ledesma, Jujuy, Argentina")));
		entityManager.persist(new People("Ricardo Bochini", new Place("Zárate, Buenos Aires, Argentina")));

		transaction.commit();
	}

	private <T> List<T> findAll(Class<T> type)
	{
		CriteriaBuilder criteriaBuilder= entityManager.getCriteriaBuilder();
		CriteriaQuery<T> criteriaQuery= (CriteriaQuery<T>) criteriaBuilder.createQuery(type);
		Root<T> from= (Root<T>) criteriaQuery.from(type);
		criteriaQuery.orderBy(criteriaBuilder.asc(from.get("id")));
		CriteriaQuery<T> select= criteriaQuery.select(from);
		TypedQuery<T> typedQuery= entityManager.createQuery(select);
		List<T> resultList= typedQuery.getResultList();
		return resultList;
	}

	public <T extends Identifiable> void saveAll(List<T> entities)
	{
		EntityTransaction transaction= entityManager.getTransaction();
		transaction.begin();

		entityManager.createQuery("DELETE FROM People").executeUpdate();
		entityManager.flush();
		transaction.commit();

		entityManager.clear();

		transaction.begin();

		for (T entity : entities)
		{
			entity.setId(null);
			entityManager.persist(entity);
		}

		transaction.commit();
	}

	public void delete(Identifiable object)
	{
		EntityTransaction transaction= entityManager.getTransaction();
		transaction.begin();
		Object merge= entityManager.merge(object);
		entityManager.remove(merge);
		entityManager.flush();
		transaction.commit();
	}

	public Identifiable add(Identifiable object)
	{
		EntityTransaction transaction= entityManager.getTransaction();
		transaction.begin();
		object.setId(null);
		entityManager.merge(object);
		entityManager.flush();
		transaction.commit();
		return object;
	}

	public void update(Identifiable object)
	{
		EntityTransaction transaction= entityManager.getTransaction();
		transaction.begin();
		entityManager.persist(entityManager.merge(object));
		entityManager.flush();
		transaction.commit();
	}

}