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问Hibernate搜索中的单返回类型
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Stack Overflow用户

提问于 2021-10-27 09:11:53

回答 1查看 149关注 0票数 0

假设我有一个有很多不同实体的应用程序，它们之间没有关系。

我想创建一个查询所有这些内容的搜索，但是返回一个统一的类型，即：

class SearchResult {
  String stype;
  String title;
  String teaser;
}

因此，我的想法是对实体进行索引，并将它们的值放入一个索引中(具有相同的索引字段)：

@Indexed(index = "idx_search")
class Book {
  @Field(name = "stype", analyze = ...)
  final String stype = "BOOK";
  @Field(name = "title", analyze = ...)
  String bookTitle;
  @Field(name = "teaser", analyze = ...)
  String bookBlurb ;
}

@Indexed(index = "idx_search")
class Person{
  @Field(name = "stype", analyze = ...)
  final String stype = "PERSON";
  @Field(name = "title", analyze = ...)
  String fullname;
  @Field(name = "teaser", analyze = ...)
  String profileIntroText;
}

@Indexed(index = "idx_search")
class Location{
  @Field(name = "stype", analyze = ...)
  final String stype = "LOCATION";      
  @Field(name = "title", analyze = ...)
  String streetPcAndCity;
  @Field(name = "teaser", analyze = ...)
  String wikiIntoText;
}

如您所见，索引名称和字段名在所有实体上是相同的。

现在我想询问他们得到这样的结果：

SearchResult[stype: PERSON, title: Spongebob, teaser: A funny sponge]
SearchResult[stype: BOOK, title: Clean Architecture , teaser: A Craftsmans Guide to Software...]
SearchResult[stype: PERSON, title: Patric, teaser: A funny seastar]
SearchResult[stype: LOCATION, title: Hannover, teaser: A city in Germany]

因此，SearchResult不是一个实体，而是将结果合并到一个类型中。索引工作正常，但在搜索时，我必须将实体类型传递给查询和QueryBuilder：

final QueryBuilder queryBuilder = fullTextEntityManager
            .getSearchFactory()
            .buildQueryBuilder()
            .forEntity(SearchResult.class)
            .get();
...

然后Hibernate返回以下错误消息：

HSEARCH000331: Can't build query for type 'SearchResult' which is neither configured nor has any configured sub-types.

你认为这有办法让这件事成功吗？

java

hibernate

hibernate-search

回答 1

Stack Overflow用户

回答已采纳

发布于 2021-10-27 09:46:06

注意，您不需要将每个类型分配给相同的索引；Hibernate搜索完全能够在一个查询中通过多个索引进行搜索。而且性能可能是相同的(Lucene索引通常被分割成多个段，不管怎么说)。

尽管如此，假设SearchResult中有一个构造函数，您可以这样做

class SearchResult {
  String stype;
  String title;
  String teaser;

  public SearchResult(String stype, String title, String teaser) {
    this.stype = stype;
    this.title = title;
    this.teaser = teaser;
  }
}

我将从Hibernate搜索6开始，因为如果您使用升级，这可能会大大减少尴尬。您将在下面的Hibernate搜索5中找到一个旧的答案。

对于Hibernate搜索6，您需要对映射进行一些更改：

@Indexed
class Book {
  @KeywordField(name = "stype", projectable = Projectable.YES)
  @IndexingDependency(reindexOnUpdate = ReindexOnUpdate.NO)
  final String stype = "BOOK";
  @FullTextField(name = "title", projectable = Projectable.YES, analyzer = ...)
  String bookTitle;
  @FullTextField(name = "teaser", projectable = Projectable.YES, analyzer = ...)
  String bookBlurb ;
}

@Indexed
class Person{
  @KeywordField(name = "stype", projectable = Projectable.YES)
  @IndexingDependency(reindexOnUpdate = ReindexOnUpdate.NO)
  final String stype = "PERSON";
  @FullTextField(name = "title", projectable = Projectable.YES, analyzer = ...)
  String fullname;
  @FullTextField(name = "teaser", projectable = Projectable.YES, analyzer = ...)
  String profileIntroText;
}

@Indexed
class Location{
  @KeywordField(name = "stype", projectable = Projectable.YES)
  @IndexingDependency(reindexOnUpdate = ReindexOnUpdate.NO)
  final String stype = "LOCATION";      
  @FullTextField(name = "title", projectable = Projectable.YES, analyzer = ...)
  String streetPcAndCity;
  @FullTextField(name = "teaser", projectable = Projectable.YES, analyzer = ...)
  String wikiIntoText;
}

但我认为搜索时的改进是值得的：

List<SearchResult> hits = Search.session(entityManager)
        .search(Arrays.asList(Book.class, Person.class, Location.class))
        .select(f -> f.composite(
                SearchResult::new,
                f.field("stype", String.class),
                f.field("title", String.class),
                f.field("teaser", String.class)))
        .where(f -> ...)
        .fetchHits( 20 );

仍然在Hibernate Search 6中(虽然我相信您至少需要6.1 )，您甚至可以使用一个接口：

interface Searchable {
  @KeywordField(projectable = Projectable.YES, analyzer = ...)
  String getStype();
  @FullTextField(projectable = Projectable.YES, analyzer = ...)
  String getTitle();
  @FullTextField(projectable = Projectable.YES, analyzer = ...)
  String getTeaser();
}

@Indexed
class Book implements Searchable {
  String bookTitle;
  String bookBlurb;

  @Override
  @javax.persistence.Transient
  @IndexingDependency(reindexOnUpdate = ReindexOnUpdate.NO)
  String getStype() {
      return "BOOK";
  }
  @Override
  @javax.persistence.Transient
  @IndexingDependency(derivedFrom = @ObjectPath(
          @PropertyValue(propertyName = "bookTitle")
  ))
  String getTitle() {
      return bookTitle;
  }
  @Override
  @javax.persistence.Transient
  @IndexingDependency(derivedFrom = @ObjectPath(
          @PropertyValue(propertyName = "bookTitle")
  ))
  String getTeaser() {
      return bookBlurb;
  }
}

@Indexed
class Person implements Searchable {
  String fullname;
  String profileIntroText;

  @Override
  @javax.persistence.Transient
  @IndexingDependency(reindexOnUpdate = ReindexOnUpdate.NO)
  String getStype() {
      return "PERSON";
  }
  @Override
  @javax.persistence.Transient
  @IndexingDependency(derivedFrom = @ObjectPath(
          @PropertyValue(propertyName = "bookTitle")
  ))
  String getTitle() {
      return bookTitle;
  }
  @Override
  @javax.persistence.Transient
  @IndexingDependency(derivedFrom = @ObjectPath(
          @PropertyValue(propertyName = "bookTitle")
  ))
  String getTeaser() {
      return bookBlurb;
  }
}

@Indexed
class Location implements Searchable {
  String streetPcAndCity;
  String wikiIntoText;

  @Override
  @javax.persistence.Transient
  @IndexingDependency(reindexOnUpdate = ReindexOnUpdate.NO)
  String getStype() {
      return "LOCATION";
  }
  @Override
  @javax.persistence.Transient
  @IndexingDependency(derivedFrom = @ObjectPath(
          @PropertyValue(propertyName = "streetPcAndCity")
  ))
  String getTitle() {
      return streetPcAndCity;
  }
  @Override
  @javax.persistence.Transient
  @IndexingDependency(derivedFrom = @ObjectPath(
          @PropertyValue(propertyName = "wikiIntoText")
  ))
  String getTeaser() {
      return wikiIntoText;
  }
}

然后你就可以这样搜索：

List<SearchResult> hits = Search.session(entityManager)
        .search(Searchable.class)
        .select(f -> f.composite(
                SearchResult::new,
                f.field("stype", String.class),
                f.field("title", String.class),
                f.field("teaser", String.class)))
        .where(f -> ...)
        .fetchHits( 20 );

或者，您可以直接加载实体：

List<Searchable> hits = Search.session(entityManager)
        .search(Searchable.class)
        .where(f -> ...)
        .fetchHits( 20 );

for (Searchable hit : hits) {
    String stype = hit.getStype();
    String title = hit.getTitle();
    String teaser = hit.getTeaser();
    if ( hit instanceof Book ) {
        ...
    }
    else if ( hit instanceof Location ) {
        ...
    }
    else { 
        ...
    } 
}

从Hibernate搜索6.2开始，通过用@ProjectionConstructor (和编译器标志)注释投影类，可以使投影更加简单：

class SearchResult {
  String stype;
  String title;
  String teaser;

  @ProjectionConstructor
  public SearchResult(String stype, String title, String teaser) {
    this.stype = stype;
    this.title = title;
    this.teaser = teaser;
  }
}

然后你就可以这样搜索：

List<SearchResult> hits = Search.session(entityManager)
        .search(Searchable.class)
        .select(SearchResult.class)
        .where(f -> ...)
        .fetchHits( 20 );

Hibernate搜索5的旧答案：

将您的字段标记为存储：

@Indexed
class Book {
  @Field(name = "stype", store = Store.YES, analyze = ...)
  final String stype = "BOOK";
  @Field(name = "title", store = Store.YES, analyze = ...)
  String bookTitle;
  @Field(name = "teaser", store = Store.YES, analyze = ...)
  String bookBlurb ;
}

@Indexed
class Person{
  @Field(name = "stype", store = Store.YES, analyze = ...)
  final String stype = "PERSON";
  @Field(name = "title", store = Store.YES, analyze = ...)
  String fullname;
  @Field(name = "teaser", store = Store.YES, analyze = ...)
  String profileIntroText;
}

@Indexed
class Location{
  @Field(name = "stype", store = Store.YES, analyze = ...)
  final String stype = "LOCATION";      
  @Field(name = "title", store = Store.YES, analyze = ...)
  String streetPcAndCity;
  @Field(name = "teaser", store = Store.YES, analyze = ...)
  String wikiIntoText;
}

然后像这样查询：

FullTextEntityManager fullTextEntityManager = Search.getFullTextEntityManager( entityManager);
final QueryBuilder queryBuilder = fullTextEntityManager
            .getSearchFactory()
            .buildQueryBuilder()
            .forEntity(Book.class)
            .get();

Query luceneQuery = ...;

FullTextQuery query = fullTextEntityManager.createFullTextQuery(query, Book.class, Person.class, Location.class);
query.setProjection("stype", "title", "teaser");
query.setMaxResults(20);

List<Object[]> arrayResults = query.list();

List<SearchResult> hits = new ArrayList<>();
for (Object[] array : arrayResults) {
    hits.add(new SearchResult((String) array[0], (String) array[1], (String) array[2]);
}

票数 3

页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持

原文链接：

https://stackoverflow.com/questions/69735853

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