我有一个模型,它有一个相当大的子实体图,hibernate最终做了大约9个语句来懒惰地获取所有需要的数据,但大约4个级别深,我得到了一个“无法初始化代理-没有会话”错误,我不知道为什么。
控制器
@Transactional(readOnly = true)
@RequestMapping(value = "/v2/plans", method = RequestMethod.GET)
public @ResponseBody List<PlanPresenter> show(HttpServletRequest request) throws Exception {
List<PlanPresenter> planPresenters = new ArrayList<>();
CriteriaBuilder criteriaBuilder = entityManager.getCriteriaBuilder();
CriteriaQuery<Plan> planQuery = criteriaBuilder.createQuery(Plan.class);
Root<Plan> root = planQuery.from(Plan.class);
if (request.getParameter("region") != null || request.getParameter("group") != null) {
List<Predicate> criteria = new ArrayList<Predicate>();
if (request.getParameter("region") != null) {
criteria.add(criteriaBuilder.equal(root.get(Plan_.region), request.getParameter("region")));
}
if (request.getParameter("group") != null) {
criteria.add(criteriaBuilder.equal(root.get(Plan_.groupCode), request.getParameter("group")));
criteria.add(root.get(Plan_.planSetId).in(groupPlanSetIds));
} else {
criteria.add(root.get(Plan_.planSetId).in(currentPlanSetIds));
}
Query query = entityManager.createQuery(planQuery.where(criteriaBuilder.and(criteria.toArray(new Predicate[]{}))));
for (Plan plan : (List<Plan>)query.getResultList()) {
planPresenters.add(new PlanPresenter(plan));
}
}
return planPresenters;
}
主持人
public class PlanPresenter {
public String id;
public String plan_set_id;
public String region;
public String name;
public String description;
public HashMap<String, Object> details = new HashMap<String, Object>();
public PlanPresenter(Plan plan) throws Exception {
this.id = String.valueOf(plan.id);
this.plan_set_id = String.valueOf(plan.planSetId);
this.region = plan.region.trim();
this.name = plan.getName();
this.description = plan.getDescription();
this.details.put("spanish_plan", plan.isSpanishPlan());
this.details.put("mutually_exclusive", plan.isMutuallyExclusive());
this.details.put("group_plan", plan.isGroupPlan());
this.details.put("group_code", plan.groupCode.trim());
this.details.put("family_plan", plan.isFamilyPlan());
this.details.put("price", plan.getPrice());
this.details.put("enrollment_fee", plan.getEnrollmentFee());
this.details.put("riders", plan.getRiders());
}
}
计划
@Entity
public class Plan implements Serializable {
private static final long serialVersionUID = 7639611964474770505L;
private static List<String> familyPlanShortNames = Arrays.asList("ABCD");
@Transient
private String description = "";
(Column definitions)
@ManyToOne(fetch = FetchType.LAZY)
@JoinColumn(name = "XXXX", insertable = false, updatable = false, nullable = true)
@NotFound(action = NotFoundAction.IGNORE)
public PlanDetail planDetail;
@OneToMany(fetch = FetchType.LAZY)
@JoinColumn(name = "XXXX", insertable = false, updatable = false, nullable = true)
@OrderBy("XXXX")
@NotFound(action = NotFoundAction.IGNORE)
public List<Rider> riders;
public String getName() {
return this.planDetail != null ? this.planDetail.longName.trim() : null;
}
public Boolean isSpanishPlan() {
return this.language.trim().equals("ES");
}
public Boolean isMutuallyExclusive() {
return this.mutuallyExclusive.trim().equals("Y");
}
public Boolean isGroupPlan() {
return this.groupCode != null && !this.groupCode.trim().equals("");
}
public Boolean isFamilyPlan() {
return familyPlanShortNames.contains(this.planDetail.shortName.trim());
}
public BigDecimal getPrice() {
return this.planDetail != null ? this.planDetail.price.setScale(2) : null;
}
public BigDecimal getEnrollmentFee() {
return this.planDetail != null ? this.planDetail.enrollmentFee.setScale(2) : null;
}
public String getDescription() {
if (this.planDetail != null && this.planDetail.brochureSections != null) {
this.planDetail.brochureSections.forEach((brochureSection) -> {
if (brochureSection.type.trim().equals("P1") && brochureSection.order == 1) {
this.description = this.description + " " + brochureSection.text.trim();
}
});
}
return this.description.trim();
}
public List<HashMap<String, Object>> getRiders() {
List<HashMap<String, Object>> riders = new ArrayList<HashMap<String, Object>>();
if (this.riders != null && this.riders.size() > 0) {
this.riders.forEach((rider) -> {
HashMap<String, Object> planRider = new HashMap<String, Object>();
planRider.put("name", rider.getName());
planRider.put("price", rider.getPrice());
planRider.put("description", rider.getDescription());
riders.add(planRider);
});
}
return riders;
}
}
计划细节
@Entity
public class PlanDetail implements Serializable {
private static final long serialVersionUID = 2256881691562712018L;
(Column definitions)
@OneToMany(fetch = FetchType.LAZY)
@JoinColumn(name = "XXXX", referencedColumnName = "XXXX", insertable = false, updatable = false, nullable = true)
@OrderBy("XXXX")
@NotFound(action = NotFoundAction.IGNORE)
public List<BrochureSection> brochureSections;
}
宣传册部分
@Entity
public class BrochureSection implements Serializable {
private static final long serialVersionUID = 1856191232387921427L;
(Column definitions)
}
例外
org.hibernate.LazyInitializationException: failed to lazily initialize a collection of role: com.models.PlanDetail.brochureSections, could not initialize proxy - no Session
at org.hibernate.collection.internal.AbstractPersistentCollection.throwLazyInitializationException(AbstractPersistentCollection.java:576) ~[hibernate-core-4.3.11.Final.jar:4.3.11.Final]
at org.hibernate.collection.internal.AbstractPersistentCollection.withTemporarySessionIfNeeded(AbstractPersistentCollection.java:215) ~[hibernate-core-4.3.11.Final.jar:4.3.11.Final]
at org.hibernate.collection.internal.AbstractPersistentCollection.initialize(AbstractPersistentCollection.java:555) ~[hibernate-core-4.3.11.Final.jar:4.3.11.Final]
at org.hibernate.collection.internal.AbstractPersistentCollection.read(AbstractPersistentCollection.java:143) ~[hibernate-core-4.3.11.Final.jar:4.3.11.Final]
at org.hibernate.collection.internal.PersistentBag.iterator(PersistentBag.java:294) ~[hibernate-core-4.3.11.Final.jar:4.3.11.Final]
at java.lang.Iterable.forEach(Iterable.java:74) ~[?:1.8.0_66]
at com.models.Plan.getDescription(Plan.java:100) ~[classes/:?]
at com.presenters.v2.PlanPresenter.<init>(PlanPresenter.java:20) ~[classes/:?]
at com.controllers.v2.PlansController.show(PlansController.java:64) ~[classes/:?]
如果你能帮忙的话,我将不胜感激。
6条答案
按热度按时间a6b3iqyw1#
如果您想保留Lazy Load,并且您使用的是Sping Boot ,只需在您的application.properties中添加以下配置即可:
carvr3hs2#
延迟加载可以保持,而无需设置enable_lazy_load_no_transs参数。我发现的最简单的解决方案是在使用Spring Data JPA时使用@ NamedLogistyGraph。https://www.baeldung.com/spring-data-jpa-named-entity-graphs
缺点是我不能在@ NamedLogistyGraph中拥有多个集合。添加第二个集合导致异常
org.hibernate.loader.MultipleBagFetchException: cannot simultaneously fetch multiple bags:
因此,如果您不想使用反模式,并且只有一个集合要加载,则@ NamedNottyGraph和@ NottyGrpah与Spring Data JPA一起使用。
bwleehnv3#
在方法上添加
@Transactional
对我来说很有效ui7jx7zq4#
spring.jpa.properties.hibernate.enable_lazy_load_no_trans=true
这是一个反模式,强烈建议避免使用它。could not initialize proxy
异常会经常发生,当子类在你的关系中包含@JsonIgnoreProperties({"hibernateLazyInitializer", "handler"})
时。我建议在你的关系中使用
fetch = FetchType.EAGER
而不是使用LAZY
。这不是最好的方法,但比使用反模式要好得多。nwsw7zdq5#
在我的例子中,我有一个类,有几个ManyToOne和ManyToMany关系。因此,需要从数据库中加载几个对象列表。我通过将这些对象转换为DTO解决了这个问题。与传递可能链接到其他对象的对象列表不同,您传递的是只包含原语和字符串的DTO列表。这是一个巨大的性能提升器
8wigbo566#
只需在服务中的方法上方添加
@Transactional
,并确保从SpringBoot而不是从jakboot导入使用transmitting