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我試圖使用標準(標準Builder和CriteriaQuery中)獲得使用CriteriaBuilder
獲得量的總和,但我收到的時候我寫的代碼錯誤的列的總和; 這裏是我的代碼
public Long findAmountByCriteria(OrderCriteria orderCriteria) {
final CriteriaBuilder criteriaBuilder = entityManager.getCriteriaBuilder();
final CriteriaQuery<BigDecimal> query = criteriaBuilder.createQuery(BigDecimal.class);
Root<Order> root = query.from(Order.class);
query.select(criteriaBuilder.sum(root.get("amount")))
.where(buildPredicateForOrderResponseCriteria(criteriaBuilder, orderCriteria, root));
final TypedQuery<BigDecimal> typedQuery = entityManager.createQuery(query);
return typedQuery.getSingleResult().longValue();
}
量爲一個BigDecimal值。
在選擇mehtod它說,
The method select(Selection<? extends BigDecimal>) in the type CriteriaQuery<BigDecimal> is not applicable for the arguments (Expression<Object>)
中和的方法,
Bound mismatch: The generic method sum(Expression<N>) of type CriteriaBuilder is not applicable for the arguments (Path<Object>). The inferred type Object is not a valid substitute for the bounded parameter <N extends Number>
我怎樣才能解決這個問題。