setFirstResult和setMaxResult不适用于Order By

问题描述

什么可能导致CriteriaQuery orderBy方法停止工作?

以下是实现:

    OpenJPAEntityManager kem = OpenJPAPersistence.cast(entityManager());
    kem.getFetchPlan().clearFetchGroups();
    kem.getFetchPlan().addFetchGroup("order_search");

    CriteriaBuilder builder = kem.getCriteriaBuilder();
    CriteriaQuery<Order> query = builder.createQuery(Order.class);
    Root<Order> order = query.from(Order.class);
    query.select(order);

    Predicate main_condition = buildWhereClause(builder, query, order, target_states, orderDate_from, orderDate_to, dueDate_from, dueDate_to, username);

    query.where(main_condition);

    query.orderBy(builder.desc(order.get("orderDate")));

    TypedQuery<Order> q = entityManager().createQuery(query);

    if (firstResult != 0)
        q.setFirstResult(firstResult);
    if (maxResults != 0)
        q.setMaxResults(maxResults);

以分页显示，当有15条记录并且我们希望每页5条记录时，它应该是:

-page1- 1 2 3 4 5 -page2- 6 7 8 9 10 -page3- 11 12 13 14 15

但是现在我们到这里了

-page1- 1 2 3 4 5 -page2- 6 7 8 9 10 -page3- 5 4 3 2 1

最后一页总是与第一页相反，为什么呢?

解决方案

将此帖子非常有用.我做了同样的事情，现在它就像一个魅力.基本上需要按条件将主键添加到订单中，否则分页将完全混乱.

花费4个小时，解决方案是如此简单而棘手.在OpenJPA 2.2.2和Oracle 11g上都可以使用，我猜这是从该帖子开始的OpenJPA 1.2以来的一个恒定技巧.

What could cause the CriteriaQuery orderBy method stop working?

Here are the implementations:

    OpenJPAEntityManager kem = OpenJPAPersistence.cast(entityManager());
    kem.getFetchPlan().clearFetchGroups();
    kem.getFetchPlan().addFetchGroup("order_search");

    CriteriaBuilder builder = kem.getCriteriaBuilder();
    CriteriaQuery<Order> query = builder.createQuery(Order.class);
    Root<Order> order = query.from(Order.class);
    query.select(order);

    Predicate main_condition = buildWhereClause(builder, query, order, target_states, orderDate_from, orderDate_to, dueDate_from, dueDate_to, username);

    query.where(main_condition);

    query.orderBy(builder.desc(order.get("orderDate")));

    TypedQuery<Order> q = entityManager().createQuery(query);

    if (firstResult != 0)
        q.setFirstResult(firstResult);
    if (maxResults != 0)
        q.setMaxResults(maxResults);

With the pagniation, when there are 15 records and we want 5 records per page, it should be:

-page1- 1 2 3 4 5 -page2- 6 7 8 9 10 -page3- 11 12 13 14 15

But now what we get here is

-page1- 1 2 3 4 5 -page2- 6 7 8 9 10 -page3- 5 4 3 2 1

the last page is always the opposite order of the first page, how come?

解决方案

Nail it, not by myself, this post is quite helpful. I did the same and now it runs like a charm. Basically need to add the primary key in to the order by criteria otherwise the pagination just totally messed.

Spend 4 hours and the solution so simple and tricky. Works on OpenJPA 2.2.2 and Oracle 11g, I guess it is a constant trick since OpenJPA 1.2 from that post.

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