Hibernate:在使用@Transactional的情况下，延迟初始化集合角色时出现了失败。

huangapple
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英文:

Hibirnate: failed to lazily initialize a collection of role with @Transactional

问题

我遇到了这样一个问题：当我惰性加载集合时，它会抛出异常。我使用了 Transactional 注解，以及 Hibernate.initialize，但在加载集合时仍然出错。只有使用 EAGER 可以解决，但这会导致开销过大。

实体类：

  1. public class Release extends AbstractEntity {
  3.     ...
  5.     @ManyToMany(fetch = FetchType.LAZY)
  6.     @JoinTable(
  7.             name = "releases_artists",
  8.             joinColumns = @JoinColumn(name = "release_id"),
  9.             inverseJoinColumns = @JoinColumn(name = "artist_id")
  10.     )
  11.     private Set<Artist> artists = new HashSet<>();
  13.     ...
  14. }

异常抛出的类：

  1. @Transactional
  2. public class ReleaseXmlReader extends XmlReaderArrays<Release> {
  4.     ...
  6.     @Override
  7.     protected void handle(Release release) {
  8.         Release releaseFromDb = releaseRepository
  9.                 .findFirstByFonalId(release.getFonalId()).orElse(null);
  10.         if (releaseFromDb != null) {
  11.             for (Artist artist : release.getArtists()) {
  12.                 if (releaseFromDb.getArtists() <--- 在这里
  13.                         .stream()
  14.                         .noneMatch(artist1 -> artist1.getDiscogsArtistId() != null)
  15.                 ) {
  16.         ....
  18.         releaseRepository.save(releaseFromDb);
  19.     }
  20. }

抽象父类：

  1. @Transactional
  2. public abstract class XmlReaderArrays<T extends AbstractEntity> {
  4.     ....
  6.     public void parse() {
  7.         try {
  8.             XMLStreamReader reader = XMLInputFactory
  9.                     .newInstance()
  10.                     .createXMLStreamReader(inputStream);
  12.             XmlMapper mapper = new XmlMapper();
  13.             while (next(reader)) {
  14.                 limit--;
  15.                 try {
  16.                     T obj = mapper.readValue(reader, type);
  17.                     handle(obj); <--- 在这里
  18.                 } catch (Exception e) {
  19.                     log.error("Error parse xml", e);
  20.                 }
  21.             }
  23.         } catch (Exception e) {
  24.             log.error("Error parse xml", e);
  25.         }
  26.     }
  28.     ...
  30. }

我尝试过只在父类或者只在子类中使用注解。我还尝试将注解放在方法上，但没有帮助。

英文:

I have such a problem: when I load the collection lazily, it throws an exception. I used the Transactional annotation, Hibernate.initialize, but it still gives an error when loading the collection. Only EAGER helps, but it will be too expensive to use.

Entity:

  1. public class Release extends AbstractEntity {
  3.     ...
  5.     @ManyToMany(fetch = FetchType.LAZY)
  6.     @JoinTable(
  7.             name = &quot;releases_artists&quot;,
  8.             joinColumns = @JoinColumn(name = &quot;release_id&quot;),
  9.             inverseJoinColumns = @JoinColumn(name = &quot;artist_id&quot;)
  10.     )
  11.     private Set&lt;Artist&gt; artists = new HashSet&lt;&gt;();
  13.     ...
  14. }

The class where the exception is thrown:

  1. @Transactional
  2. public class ReleaseXmlReader extends XmlReaderArrays&lt;Release&gt; {
  4.     ...
  6.     @Override
  7.     protected void handle(Release release) {
  8.         Release releaseFromDb = releaseRepository
  9.                 .findFirstByFonalId(release.getFonalId()).orElse(null);
  10.         if (releaseFromDb != null) {
  11.             for (Artist artist : release.getArtists()) {
  12.                 if (releaseFromDb.getArtists() &lt;-- HERE
  13.                         .stream()
  14.                         .noneMatch(artist1 -&gt; artist1.getDiscogsArtistId() != null)
  15.                 ) {
  16.         ....
  18.              
  20.         releaseRepository.save(releaseFromDb);
  21.     }
  22. }

Parent abstract class:

  1. @Transactional
  2. public abstract class XmlReaderArrays&lt;T extends AbstractEntity&gt; {
  4.     ....
  6.     public void parse() {
  7.         try {
  8.             XMLStreamReader reader = XMLInputFactory
  9.                     .newInstance()
  10.                     .createXMLStreamReader(inputStream);
  12.             XmlMapper mapper = new XmlMapper();
  13.             while (next(reader)) {
  14.                 limit--;
  15.                 try {
  16.                     T obj = mapper.readValue(reader, type);
  17.                     handle(obj); &lt;--- HERE
  18.                 } catch (Exception e) {
  19.                     log.error(&quot;Error parse xml&quot;, e);
  20.                 }
  21.             }
  23.         } catch (Exception e) {
  24.             log.error(&quot;Error parse xml&quot;, e);
  25.         }
  26.     }
  27.   
  28.     ...
  30. }

I tried to match annotation only with the parent class or only with the inheritor. I also tried to put the annotation on the methods, but it did not help.

答案1

得分: 1

为了使 @Transactional 起作用，Spring AOP 需要在您的 bean 上创建代理。这里有两个问题：

  1. 在这里，您并没有使用 bean，只是将 handle 作为同一类的方法。您必须注入一个 bean 并将其用作代理。

  2. 这个方法是 protected 的，但是它必须是 public 的才能使 @Transactional 起作用。

英文:

In order for @Transactional to work, spring AOP needs to create a proxy over your bean. There are 2 issues here:

  1. Here you're not using bean, just using handle as the method of the same class. You would have to inject a bean to use it as proxy.

  2. The method is protected, but it has to be public for the @Transactional to work.

huangapple
  • 本文由 发表于 2020年10月16日 15:15:18
  • 转载请务必保留本文链接：https://go.coder-hub.com/64384557.html
  • hibernate
  • hibernate-mapping
  • java
  • spring
  • spring-boot
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