java 如何使用 Hibernate\HQL 返回 Map<Key, Value>
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How to return Map<Key, Value> with Hibernate\HQL
提问by Shvalb
I have an entry as follow:
我有一个条目如下：
@Entity
@Table(name="rank")
class Rank implements Serializable {
private int id;
private int rank_id;
private date creationDate;
...
// getters\setters...
}
I would like to query this table and put the results into a HashMap! as follow:
我想查询这个表并将结果放入一个HashMap中！如下：
Map<Integer, Rank> = session.createSQL("select new map...").list();
Is this possible to put the entity as the value of the map?
这是否可以将实体作为地图的值？
Can I get a code example?
我可以得到一个代码示例吗？
回答by Sertage
Yes, for example:
是的，例如：
Select new Map(r.id,r) FROM Rank r
Select new Map(r.id,r) FROM Rank r
But that will return a list of Maps. You should take a look hereto understand better.
但这将返回一个地图列表。你应该看看这里以更好地理解。
Edit:To explain better, the return will be something like this:
编辑：为了更好地解释，返回将是这样的：
List<Map<Long, Rank>> ranks = (List<Map<Long, Rank>>) session.createQuery("select new Map<r.rankId,r> FROM Rank r").list();
It is one Map for each record. To put all in only one map, unfortunately, it has to be manually:
每个记录是一个 Map。不幸的是，要将所有内容放在一张地图中，必须手动进行：
List<Rank> ranks = (List<Rank>) session.createQuery("select new r FROM Rank r").list();
Map<Long, Rank> mapRanks = new HashMap<Long, Rank>();
for (Rank rank : ranks) {
if (!map.contains(rank.getId()) {
map.put(rank.getId(), rank);
}
}
