Example usage for javax.persistence.criteria ListJoin as

Introduction

In this page you can find the example usage for javax.persistence.criteria ListJoin as.

Prototype

<X> Expression<X> as(Class<X> type);

Source Link

Document

Perform a typecast upon the expression, returning a new expression object.

Usage

From source file:org.apereo.portal.persondir.dao.jpa.JpaLocalAccountDaoImpl.java

@Override
public List<ILocalAccountPerson> getPeople(LocalAccountQuery query) {
    final EntityManager entityManager = this.getEntityManager();
    final CriteriaBuilder cb = entityManager.getCriteriaBuilder();

    final CriteriaQuery<LocalAccountPersonImpl> criteriaQuery = cb.createQuery(LocalAccountPersonImpl.class);
    final Root<LocalAccountPersonImpl> accountRoot = criteriaQuery.from(LocalAccountPersonImpl.class);
    final CollectionJoin<LocalAccountPersonImpl, LocalAccountPersonAttributeImpl> attributes = accountRoot
            .join(LocalAccountPersonImpl_.attributes);
    final ListJoin<LocalAccountPersonAttributeImpl, String> attributeValues = attributes
            .join(LocalAccountPersonAttributeImpl_.values);

    //Due to the joins multiple rows are returned for each result
    criteriaQuery.distinct(true);//w w w .  jav a 2s  .  c  om
    criteriaQuery.select(accountRoot);

    final List<Predicate> whereParts = new LinkedList<Predicate>();
    final Map<Parameter<String>, String> params = new LinkedHashMap<Parameter<String>, String>();

    // if a username has been specified, append it to the query
    if (query.getName() != null) {
        whereParts.add(cb.equal(accountRoot.get(LocalAccountPersonImpl_.name), this.nameParameter));
        params.put(this.nameParameter, query.getName());
    }

    //Build Predicate for each attribute being queried
    int paramCount = 0;
    for (Map.Entry<String, List<String>> entry : query.getAttributes().entrySet()) {
        final List<String> values = entry.getValue();
        if (values == null) {
            continue;
        }

        //For each value create a Predicate checking the attribute name and value together
        for (final String value : values) {
            if (StringUtils.isBlank(value)) {
                continue;
            }

            //Create Parameter objects for the name and value, stick them in the params map for later use
            final ParameterExpression<String> nameParam = this.createParameterExpression(String.class,
                    "attrName" + paramCount);
            final ParameterExpression<String> valueParam = this.createParameterExpression(String.class,
                    "attrValue" + paramCount);

            params.put(nameParam, entry.getKey());
            params.put(valueParam, "%" + value.toLowerCase() + "%");

            //Build the and(eq, like) predicate and add it to the list of predicates for the where clause
            whereParts.add(cb.and(cb.equal(attributes.get(LocalAccountPersonAttributeImpl_.name), nameParam),
                    cb.like(cb.lower(attributeValues.as(String.class)), valueParam)));

            paramCount++;
        }
    }

    //Add the Predicates to the where clause
    criteriaQuery.where(cb.or(whereParts.toArray(new Predicate[whereParts.size()])));

    //Create the query
    final TypedQuery<LocalAccountPersonImpl> jpaQuery = this.createCachedQuery(criteriaQuery);

    //Add all of the stored up parameters to the query
    for (Map.Entry<Parameter<String>, String> entry : params.entrySet()) {
        final Parameter<String> parameter = entry.getKey();
        final String value = entry.getValue();
        jpaQuery.setParameter(parameter, value);
    }

    final List<LocalAccountPersonImpl> accounts = jpaQuery.getResultList();
    return new ArrayList<ILocalAccountPerson>(accounts);
}

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