Example usage for javax.persistence.criteria CriteriaQuery from

Introduction

In this page you can find the example usage for javax.persistence.criteria CriteriaQuery from.

Prototype

<X> Root<X> from(Class<X> entityClass);

Source Link

Document

Create and add a query root corresponding to the given entity, forming a cartesian product with any existing roots.

Usage

From source file:com.creditcloud.common.entities.dao.AbstractReadDAO.java

public <K> T findBy(String fieldName, Object value, Class<K> valueClass) {
    EntityManager em = getEntityManager();
    CriteriaBuilder cb = em.getCriteriaBuilder();
    CriteriaQuery<T> cq = cb.createQuery(entityClass);
    Root<T> root = cq.from(entityClass);
    cq.select(root).where(cb.equal(root.get(fieldName).as(valueClass), value));
    List<T> list = em.createQuery(cq).getResultList();
    return list.isEmpty() ? null : list.get(0);
}

From source file:com.creditcloud.common.entities.dao.AbstractReadDAO.java

/**
 * list all entity//w  w w  .  j av  a  2s  .  co m
 *
 * @return
 */
public List<T> findAll() {
    EntityManager em = getEntityManager();
    CriteriaQuery cq = em.getCriteriaBuilder().createQuery();
    cq.select(cq.from(entityClass));
    return em.createQuery(cq).getResultList();
}

From source file:eu.uqasar.service.AbstractService.java

private List<T> getRange(int first, int count) {
    logger.infof("loading %d %s starting from %d  ...", count, readableClassName, first);
    CriteriaBuilder cb = em.getCriteriaBuilder();
    CriteriaQuery<T> query = cb.createQuery(this.clazz);
    query.from(this.clazz);
    return em.createQuery(query).setFirstResult(first).setMaxResults(count).getResultList();
}

From source file:bq.jpa.demo.query.criteria.service.CriteriaService.java

/**
 * SELECT e FROM jpa_query_employee//from   w  w w.j a v a2  s  .co  m
 */
@Transactional
public void doSimple() {
    CriteriaBuilder cb = em.getCriteriaBuilder();
    CriteriaQuery<Employee> c = cb.createQuery(Employee.class);
    Root<Employee> e = c.from(Employee.class);
    c.select(e);

    showResult(c);
}

From source file:bq.jpa.demo.query.criteria.service.CriteriaService.java

/**
 * SELECT e FROM jpa_query_employee e WHERE e.name='employee_1'
 *///w  w w  .  j ava  2  s  .c  om
@Transactional
public void doSimple2() {
    CriteriaBuilder cb = em.getCriteriaBuilder();
    CriteriaQuery<Employee> c = cb.createQuery(Employee.class);
    Root<Employee> e = c.from(Employee.class);
    c.select(e).where(cb.equal(e.get("name"), "employee_1"));

    showResult(c);
}

From source file:eu.uqasar.service.AbstractService.java

protected List<T> getAllOrdered(Class<T> clazz, Order... orders) {
    logger.infof("loading all %ss ...", getReadableClassName(clazz));
    CriteriaBuilder cb = em.getCriteriaBuilder();
    CriteriaQuery<T> criteria = cb.createQuery(clazz);
    criteria.from(clazz);
    if (orders != null && orders.length > 0) {
        criteria.orderBy(orders);//from   w ww  .j a  va  2s .co  m
    }
    return em.createQuery(criteria).getResultList();
}

From source file:bq.jpa.demo.query.criteria.service.CriteriaService.java

/**
 * group by and having ://from w  w w .j av a 2 s . c o  m
 * SELECT e, COUNT(p) FROM jpa_query_employee e JOIN e.projects p GROUP BY e HAVING COUNT(p) >= 2
 */
@Transactional
public void doGroupby() {
    CriteriaBuilder cb = em.getCriteriaBuilder();
    CriteriaQuery<Object[]> c = cb.createQuery(Object[].class);
    Root<Employee> e = c.from(Employee.class);
    Join<Employee, Project> p = e.join("projects");
    c.multiselect(e, cb.count(p)).groupBy(e).having(cb.ge(cb.count(p), 2));

    showResult(c);
}

From source file:bq.jpa.demo.query.criteria.service.CriteriaService.java

/**
 * out join//from   w w w .  j  a v  a  2 s  .com
 */
@Transactional
public void doFrom2() {
    CriteriaBuilder cb = em.getCriteriaBuilder();
    CriteriaQuery<Object[]> c = cb.createQuery(Object[].class);
    Root<Employee> e = c.from(Employee.class);
    Join<Object, Object> address = e.join("address", JoinType.LEFT);
    Join<Object, Object> department = e.join("department", JoinType.LEFT);
    c.multiselect(e, address, department);

    showResult(c);
}

From source file:com.creditcloud.common.entities.dao.AbstractReadDAO.java

/**
 * find entity in the range/*from w w  w .  j a v a  2s . c o  m*/
 *
 * @param range
 * @return
 */
public List<T> findRange(int[] range) {
    EntityManager em = getEntityManager();
    CriteriaQuery cq = em.getCriteriaBuilder().createQuery();
    cq.select(cq.from(entityClass));
    Query q = em.createQuery(cq);
    q.setMaxResults(range[1] - range[0]);
    q.setFirstResult(range[0]);
    return q.getResultList();
}

From source file:bq.jpa.demo.query.criteria.service.CriteriaService.java

/**
 * multiple select// ww  w  .java  2 s.c om
 */
public void doSelect2() {
    CriteriaBuilder cb = em.getCriteriaBuilder();

    // method1: tuple
    CriteriaQuery<Tuple> tupleQuery = cb.createTupleQuery();
    Root<Employee> e1 = tupleQuery.from(Employee.class);
    tupleQuery.select(cb.tuple(e1.get("id"), e1.get("name")));
    showResult(tupleQuery);

    // method2: object[] and criteriaquery.multiselec
    CriteriaQuery<Object[]> multiQuery = cb.createQuery(Object[].class);
    Root<Employee> e2 = multiQuery.from(Employee.class);
    multiQuery.multiselect(e2.get("id"), e2.get("name"));
    showResult(multiQuery);
}