To make query result pagination slightly easier to use, introduce {{Pager}}, which may be used as follows:
{code:java} Pager<Book> bookPager =
session.createSelectionQuery("from Book where title like :title", Book.class)
.setParameter("title", titlePattern)
.getResultPager(Page.first(pageSize));
while (bookPager.hasResults()) {
List<Book> books = bookPager.getResultList();
...
session.clear();
bookPager.next();
}{code}
Or as follows:
{code:java} session.createSelectionQuery("from Book where title like :title", Book.class)
.setParameter("title", titlePattern)
.getResultPager(Page.first(pageSize))
.forEachRemainingPage(books -> {
...
session.clear();
});{code}
Or even, more practically for most programs, something like this:
{ noformat code:java }scope.inSession(s -> {
Page page = Page.first(10);
boolean hasMore;
do {
Pager<Book> pager = s.createSelectionQuery("from Book", Book.class)
.getResultPager(Page.first(15));
List<Book> books = pager.getResultList();
hasMore = pager.hasResultsOnNextPage();
page = page.next();
} while ( hasMore );
});{ noformat code }
Here we do not need to keep a {{Pager}} open between requests.
Still need to add {{Page.getTotalPages()}} delegating to a new method {{Query.getResultCount()}}. |
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