Spring数据JPA-“无法初始化代理-无会话”-方法标记为事务性

Question

我有一个模型，它有一个相当大的子实体图，hibernate最终生成了大约9条语句来懒洋洋地获取所需的所有数据，但大约有4层深，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;
}

节目主持人

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;
  }
}

计划详情

@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;
}

小册子部分

@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/:?]

任何帮助都将不胜感激。

Answer 1

我也有同样的例外，问题是，我有一个实体没有映射

@Entity
Class A {
}

@Entity
Class B {

   private A a;
}

解决方案

@Entity
Class B {

  @OneToOne
  @MapsId
  private A a;
}

Answer 2

可以保留延迟加载，而无需设置enable\u lazy\u load\u no\u trans参数。我找到的最简单的解决方案是在使用Spring数据JPA时使用@NamedEntityGraph。https://www.baeldung.com/spring-data-jpa-named-entity-graphs

缺点是@NamedEntityGraph中不能有多个集合。添加第二个集合导致异常组织。冬眠装载机。MultipleBagFetchException：无法同时提取多个行李：

因此，如果您不想使用反模式，并且只有一个要尝试加载的集合，@NamedEntityGraph和@EntityGrpah适用于Spring Data JPA。

Answer 3

如果你想保持延迟加载，并且你正在使用Spring Boot，只需在application.properties中添加以下配置：

spring.jpa.properties.hibernate.enable_lazy_load_no_trans=true