Example usage for javax.persistence.criteria Selection getClass

Introduction

In this page you can find the example usage for javax.persistence.criteria Selection getClass.

Prototype

@HotSpotIntrinsicCandidate
public final native Class<?> getClass();

Source Link

Document

Returns the runtime class of this Object .

Usage

From source file:com.impetus.kundera.persistence.CriteriaQueryTranslator.java

/**
 * Method to translate criteriaQuery into JPQL.
 * /*from www.ja  v a2 s  . co  m*/
 * @param criteriaQuery
 *            criteria query.
 * 
 * @return JPQL string.
 */
static <S> String translate(CriteriaQuery criteriaQuery) {
    QueryBuilder builder = new CriteriaQueryTranslator.QueryBuilder();

    // validate if criteria query is valid

    /**
     * select, from clause is mandatory
     * 
     * multiple from clause not support where clause is optional
     * 
     */

    Selection<S> select = criteriaQuery.getSelection();

    if (select != null) {
        builder.appendSelectClause();

    }

    if (select.getClass().isAssignableFrom(DefaultCompoundSelection.class)
            && ((CompoundSelection) select).isCompoundSelection()) {
        List<Selection<?>> selections = ((CompoundSelection) select).getCompoundSelectionItems();
        builder.appendMultiSelect(selections);
    } else if (select instanceof AggregateExpression) {
        builder.appendAggregate(((AggregateExpression) select).getAggregation());
    } else {
        String alias = select.getAlias();

        if (!StringUtils.isEmpty(alias)) {
            builder.appendAlias(alias);
        }

        Attribute attribute = ((DefaultPath) select).getAttribute();

        if (attribute != null) {
            builder.appendAttribute(attribute);
        }
    }
    Class<? extends S> clazzType = select.getJavaType();

    Set<Root<?>> roots = criteriaQuery.getRoots();

    Root<?> from = roots.iterator().next();

    Class entityClazz = from.getJavaType();

    builder.appendFromClause();

    // select.alias(paramString)
    builder.appendFrom(entityClazz);
    builder.appendAlias(from.getAlias() != null ? from.getAlias() : select.getAlias());
    Predicate where = criteriaQuery.getRestriction(); // this could be null.
    if (where != null) {
        builder.appendWhereClause();
        List<Expression<Boolean>> expressions = where.getExpressions();
        for (Expression expr : expressions) {
            builder.appendWhere(expr, from.getAlias());
        }

    }

    List<Order> orderings = criteriaQuery.getOrderList();

    if (orderings != null) {
        if (!orderings.isEmpty()) {
            builder.appendOrderClause(where == null);
        }

        for (Order order : orderings) {
            builder.appendAlias(from.getAlias() != null ? from.getAlias() : select.getAlias());
            builder.appendOrdering(order);
        }
    }
    return builder.getQuery();

    // check that roots has to be one. multiple clause not yet supported

}

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