英文:
Fetch concurrent tables with Criteria API
问题
我有3个实体类：
（BaseAutoIncrementModel包含每个实体的id声明）
表1：Dossier
@Entity
@Table(name = "DOSSIER", schema = "ADOP")
public class Dossier extends BaseAutoIncrementModel<Integer> implements BaseModelCode<Integer> {
...
}
表2：AlerteDossier
@Entity
@Table(name = "ALERTE_DOSSIER", schema = "ADOP")
public class AlerteDossier extends BaseAutoIncrementModel<Integer> implements BaseModelCode<Integer> {
@ManyToOne(fetch = FetchType.LAZY, optional = false)
@JoinColumn(name = "FK_DOSSIER")
private Dossier dossier;
...
}
表3：AlerteEnvoi
@Entity
@Table(name = "ALERTE_ENVOI", schema = "ADOP")
public class AlerteEnvoi extends BaseAutoIncrementModel<Integer> implements BaseModelCode<Integer> {
@ManyToOne(fetch = FetchType.EAGER, optional = false)
@JoinColumn(name = "FK_ALERTE_DOSSIER")
private AlerteDossier alerteDossier;
...
}
我目前有：
CriteriaBuilder builder = getEntityManager().getCriteriaBuilder();
CriteriaQuery<AlerteEnvoi> query = builder.createQuery(AlerteEnvoi.class);
Root<AlerteEnvoi> root = query.from(AlerteEnvoi.class);
query.select(root);
List<Predicate> predicateList = new ArrayList<>();
...
正如您在AlerteEnvoi中所看到的，AlerteDossier表是急加载的，尽管在AlerteDossier中，Dossier表是惰加载的。
我需要使用 Criteria Api 创建一个选择语句，以便在 AlerteDossier 实体中也加载 Dossier。
如果 AlerteDossier 是惰性加载的，我知道如何在 AlerteEnvoi 中获取 AlerteDossier（root.fetch("alerteDossier", JoinType.LEFT)），但我不知道如何获取子实体的子实体。有人能帮我解决这个问题吗？
英文:
I've got 3 entity classes:
(The BaseAutoIncrementModel contains the declaration of the id for each entity)
Table 1: Dossier
@Entity
@Table(name = "DOSSIER", schema = "ADOP")
public class Dossier extends BaseAutoIncrementModel<Integer> implements BaseModelCode<Integer> {
...
}
Table 2: AlerteDossier
@Entity
@Table(name = "ALERTE_DOSSIER", schema = "ADOP")
public class AlerteDossier extends BaseAutoIncrementModel<Integer> implements BaseModelCode<Integer> {
@ManyToOne(fetch = FetchType.LAZY, optional = false)
@JoinColumn(name = "FK_DOSSIER")
private Dossier dossier;
...
}
Table 3: AlerteEnvoi
@Entity
@Table(name = "ALERTE_ENVOI", schema = "ADOP")
public class AlerteEnvoi extends BaseAutoIncrementModel<Integer> implements BaseModelCode<Integer> {
@ManyToOne(fetch = FetchType.EAGER, optional = false)
@JoinColumn(name = "FK_ALERTE_DOSSIER")
private AlerteDossier alerteDossier;
...
}
What I have atm:
CriteriaBuilder builder = getEntityManager().getCriteriaBuilder();
CriteriaQuery<AlerteEnvoi> query = builder.createQuery(AlerteEnvoi.class);
Root<AlerteEnvoi> root = query.from(AlerteEnvoi.class);
query.select(root);
List<Predicate> predicateList = new ArrayList<>();
...
As you can see in AlerteEnvoi the AlerteDossier table is eagerly loaded, though in AlerteDossier the Dossier table is lazily loaded.
I need to create, using the Criteria Api, a select statement for AlerteEnvoi where Dossier would also be loaded within the AlerteDossier entity.
I know how I'd need to fetch the AlerteDossier within the AlerteEnvoi if AlerteDossier would be lazily-loaded (root.fetch("alerteDossier", JoinType.LEFT), I've got no clue how to fetch a sub-entity of a sub-entity though. Anyone can help me with this?
答案1
得分: 0
我还没有进行测试，但从同事那里听说应该可以这样做：
Fetch<AlerteEnvoi, AlerteDossier> fetchAlerteDossier = root.fetch("alerteDossier", JoinType.LEFT);
fetchAlerteDossier.fetch("dossier", JoinType.LEFT);
我会在测试之后将此答案标记为已接受。
英文:
I haven't tested it out yet, but heard from a collegue something like this should be do-able:
Fetch<AlerteEnvoi, AlerteDossier> fetchAlerteDossier = root.fetch("alerteDossier", JoinType.LEFT);
fetchAlerteDossier.fetch("dossier", JoinType.LEFT);
I'll be putting this answer as accepted once I've tested it out.
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