Java JPA多链接错误实体
假设我们有4个实体:电影、工作室、站点和标签。电影、工作室和站点可以有0个或多个标记(一个标记的每个标记都有0到多个)。一部电影有0或1个站点(一个站点有0到多部电影)。一部电影有0个或多个工作室(一个工作室有0到多个电影)。我通过如下介绍TagCollection和StudioCollection实现了这些关系。TagCollection具有带电影的一对一映射,以及带Tag的多对多映射(与StudioCollection相同)。我这样做是因为:Java JPA多链接错误实体,java,hibernate,spring-boot,jpa,Java,Hibernate,Spring Boot,Jpa,假设我们有4个实体:电影、工作室、站点和标签。电影、工作室和站点可以有0个或多个标记(一个标记的每个标记都有0到多个)。一部电影有0或1个站点(一个站点有0到多部电影)。一部电影有0个或多个工作室(一个工作室有0到多个电影)。我通过如下介绍TagCollection和StudioCollection实现了这些关系。TagCollection具有带电影的一对一映射,以及带Tag的多对多映射(与StudioCollection相同)。我这样做是因为: 我希望所有标记/工作室都转到同一个表,而不管它
- 我希望所有标记/工作室都转到同一个表,而不管它们附加到哪个实体
- 链接表将有一个唯一的id返回到所属实体,这意味着当我查询关系时,我永远不必指定标记是用于电影、网站还是工作室:该id是唯一的,仅存在于一个实体
@Test
public void addedMoviesWithAttributesArePersisted() {
final MovieBuilder mb = new MovieBuilder();
mb.title("Title");
// Add a site to the movie
final Site site = new Site("Site TEst");
mb.site(site);
//Add 2 studios to the movie
final Studio studio1 = new Studio("Studio 1");
final Studio studio2 = new Studio("Studio 2");
final StudioCollection studioCollection = new StudioCollection();
studioCollection.add(Sets.newSet(studio1, studio2));
mb.studioCollections(studioCollection);
// Add 2 tags to the movie
final Tag tag1 = new Tag("Tag 1");
final Tag tag2 = new Tag("Tag 2");
final TagCollection tagCollection = new TagCollection();
tagCollection.add(Sets.newSet(tag1, tag2));
mb.tagCollection(tagCollection);
final Movie movie = mb.build();
this.underTest.persist(movie);
final Set<Movie> foundMovies = this.underTest.findByTitle("Title");
assertFalse(foundMovies.isEmpty());
assertEquals(1, foundMovies.size());
assertTrue(foundMovies.contains(movie));
final Movie foundMovie = foundMovies.iterator().next();
// This fails
assertFalse(foundMovie.getTagCollection().isEmpty());
// Querying for all entities gives this results
this.underTest.getAll();
// TagCollection: id=[1] Values=[[]]
// TagCollection: id=[2] Values=[[Tag [id=1, tagName=Tag 1], Tag [id=2, tagName=Tag 2]]]
// TagCollection: id=[3] Values=[[]]
// TagCollection: id=[4] Values=[[]]
// Site: id=[1] + Name=Site TEst] + tag=[TagCollection: id=[1] Values=[[]]]
// Studio id=[1] + Name=Studio 2] + tag=[TagCollection: id=[1] Values=[[]]]
// Studio id=[2] + Name=Studio 1] + tag=[TagCollection: id=[2] Values=[[Tag [id=1, tagName=Tag 1], Tag [id=2, tagName=Tag 2]]]]
// Movie: id=[1] + Title=Title] + tag=[TagCollection: id=[1] Values=[[]]]
}
标签收集:
@Entity
@Table(name = "TAG_COLLECTION")
public class TagCollection {
@Id
@GeneratedValue(strategy = GenerationType.AUTO)
private long id;
@ManyToMany(fetch = FetchType.EAGER, cascade = { CascadeType.PERSIST, CascadeType.MERGE, CascadeType.REFRESH })
@JoinTable(name = "tag_link", joinColumns = @JoinColumn(name = "tagCollection_id"), inverseJoinColumns = @JoinColumn(name = "tag_id"))
private final Set<Tag> tags = new HashSet<>();
// Getter & Setter and constructors
}
@Entity
@Table(name = "STUDIO_COLLECTION")
public class StudioCollection {
@Id
@GeneratedValue(strategy = GenerationType.AUTO)
private long id;
@ManyToMany(fetch = FetchType.EAGER, cascade = { CascadeType.PERSIST, CascadeType.MERGE, CascadeType.REFRESH })
@JoinTable(name = "studio_link", joinColumns = @JoinColumn(name = "studioCollection_id"), inverseJoinColumns = @JoinColumn(name = "studio_id"))
private final Set<Studio> studios = new HashSet<>();
// Getter & Setter and constructors
}
演播室:
@Entity
@Table(name = "STUDIO")
public class Studio implements MovieEntity, Representable, Taggable {
@Id
@GeneratedValue(strategy = GenerationType.AUTO)
private Long id;
@NotNull
@NotEmpty
@Size(min = 1)
@Column(unique = true, nullable = false)
private String name;
@OneToOne(cascade = { CascadeType.PERSIST, CascadeType.MERGE, CascadeType.REFRESH })
@JoinColumn(name = "id")
private final TagCollection tags = new TagCollection();
// Getter & Setter and constructors
}
工作室收藏:
@Entity
@Table(name = "TAG_COLLECTION")
public class TagCollection {
@Id
@GeneratedValue(strategy = GenerationType.AUTO)
private long id;
@ManyToMany(fetch = FetchType.EAGER, cascade = { CascadeType.PERSIST, CascadeType.MERGE, CascadeType.REFRESH })
@JoinTable(name = "tag_link", joinColumns = @JoinColumn(name = "tagCollection_id"), inverseJoinColumns = @JoinColumn(name = "tag_id"))
private final Set<Tag> tags = new HashSet<>();
// Getter & Setter and constructors
}
@Entity
@Table(name = "STUDIO_COLLECTION")
public class StudioCollection {
@Id
@GeneratedValue(strategy = GenerationType.AUTO)
private long id;
@ManyToMany(fetch = FetchType.EAGER, cascade = { CascadeType.PERSIST, CascadeType.MERGE, CascadeType.REFRESH })
@JoinTable(name = "studio_link", joinColumns = @JoinColumn(name = "studioCollection_id"), inverseJoinColumns = @JoinColumn(name = "studio_id"))
private final Set<Studio> studios = new HashSet<>();
// Getter & Setter and constructors
}
这似乎是您所描述的: 但你的实体似乎与你的概念模型不匹配。您可以对上述ER图进行如下建模:
@Entity
public class Tag {
@Id @GeneratedValue private int id;
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
@ManyToMany private Set<Movie> movieTags;
@ManyToMany private Set<Studio> studioTags;
@ManyToMany private Set<Site> siteTags;
@Entity
public class Movie {
@Id @GeneratedValue private int id;
@ManyToMany(mappedBy="movieTags") private Set<Tag> tags;
@ManyToOne private Studio studio;
@ManyToOne private Site site;
@Entity
public class Site {
@Id @GeneratedValue private int id;
@ManyToMany(mappedBy="siteTags") private Set<Tag> tags;
@OneToMany(mappedBy="site") private Set<Movie> movies;
@Entity
public class Studio {
@Id @GeneratedValue private int id;
@ManyToMany(mappedBy="studioTags") private Set<Tag> tags;
@OneToMany(mappedBy="studio") private Set<Movie> movies;
@实体
公共类标签{
@Id@GeneratedValue private int Id;
公共int getId(){
返回id;
}
公共无效集合id(内部id){
this.id=id;
}
@许多私人电影;
@许多私人设置的学习包;
@许多私人设置的站点标签;
@实体
公映{
@Id@GeneratedValue private int Id;
@许多(mappedBy=“movieTags”)私有设置标签;
@多通私人工作室;
@许多私人网站;
@实体
公共类网站{
@Id@GeneratedValue private int Id;
@ManyToMany(mappedBy=“siteTags”)私有集标签;
@OneToMany(mappedBy=“site”)私人电影;
@实体
公营演播室{
@Id@GeneratedValue private int Id;
@ManyToMany(mappedBy=“studioTags”)私有集标签;
@OneToMany(mappedBy=“studio”)私人电影;
并像这样使用它:
tx.begin();
Tag tag = new Tag();
Movie movie = new Movie();
Studio studio = new Studio();
Site site = new Site();
tag.setMovies(new HashSet<>(Arrays.asList(movie)));
tag.setStudios(new HashSet<>(Arrays.asList(studio)));
tag.setSites(new HashSet<>(Arrays.asList(site)));
site.setMovies(new HashSet<>(Arrays.asList(movie)));
studio.setMovies(new HashSet<>(Arrays.asList(movie)));
em.persist(movie);
em.persist(site);
em.persist(studio);
em.persist(tag);
tx.commit();
em.clear();
List<Tag> r = em.createQuery("select distinct t from Tag t left join fetch t.movieTags left join fetch t.studioTags left join fetch t.siteTags", Tag.class).getResultList();
System.out.println(r.get(0)
+ Arrays.toString(r.get(0).getMovies().toArray())
+":"+Arrays.toString(r.get(0).getStudios().toArray())
+":"+Arrays.toString(r.get(0).getSites().toArray()));
tx.begin();
标签=新标签();
电影=新电影();
Studio=新建Studio();
站点=新站点();
setMovies(新的HashSet(Arrays.asList(movie));
tag.setStudios(新的HashSet(Arrays.asList(studio));
tag.setSites(新的HashSet(Arrays.asList(site));
setMovies(新的HashSet(Arrays.asList(movie));
setMovies(新的HashSet(Arrays.asList(movie));
em.persist(电影);
em.persist(site);
em.persist(工作室);
em.persist(tag);
tx.commit();
em.clear();
List r=em.createQuery(“从标记t中选择不同的t left join fetch t.movieTags left join fetch t.studioTags left join fetch t.siteTags”,Tag.class).getResultList();
System.out.println(r.get(0)
+Arrays.toString(r.get(0.getMovies().toArray())
+“:”+Arrays.toString(r.get(0.getStudios().toArray())
+“:”+Arrays.toString(r.get(0.getSites().toArray());
对于SO问题来说,这可能太复杂了。感谢您的时间和回答。它帮助我实现了我想要的
tx.begin();
Tag tag = new Tag();
Movie movie = new Movie();
Studio studio = new Studio();
Site site = new Site();
tag.setMovies(new HashSet<>(Arrays.asList(movie)));
tag.setStudios(new HashSet<>(Arrays.asList(studio)));
tag.setSites(new HashSet<>(Arrays.asList(site)));
site.setMovies(new HashSet<>(Arrays.asList(movie)));
studio.setMovies(new HashSet<>(Arrays.asList(movie)));
em.persist(movie);
em.persist(site);
em.persist(studio);
em.persist(tag);
tx.commit();
em.clear();
List<Tag> r = em.createQuery("select distinct t from Tag t left join fetch t.movieTags left join fetch t.studioTags left join fetch t.siteTags", Tag.class).getResultList();
System.out.println(r.get(0)
+ Arrays.toString(r.get(0).getMovies().toArray())
+":"+Arrays.toString(r.get(0).getStudios().toArray())
+":"+Arrays.toString(r.get(0).getSites().toArray()));