java - Spring Data Native 查询 Lob 列的有趣错误

Question

我有一个实体:

@Entity public class KnowledgeBase {

    private Long id;
    private String link;
    private String content;

    @Id
    @SequenceGenerator(name = "knowledgebase_id_generator", sequenceName = "knowledgebase_id_sequence", allocationSize = 1)
    @GeneratedValue(strategy = GenerationType.SEQUENCE, generator = "knowledgebase_id_generator")
    public Long getId() {
        return id;
    }

    public void setId(Long id) {
        this.id = id;
    }

    public String getLink() {
        return link;
    }

    public void setLink(String link) {
        this.link = link;
    }

    public String getContent() {
        return content;
    }

    public void setContent(String content) {
        this.content = content;
    }
}

我有一个 Spring 数据存储库

@Repository public interface KnowledgeBaseRepository
        extends AbstractRepository<KnowledgeBase, Long> {

    @Query(value = "SELECT c.id as id,c.link as link, c.content as content"
            + " from knowledgebase c where content=?1", nativeQuery = true)
    List<KnowledgeBase> findRelevantRecords(String searchString);
}

请注意

where content=?1

只是一个示例，测试时的 where 子句有所不同。

问题是，如果我运行这个存储库方法，一切都很好，但内容列包含大量文本，我希望它是延迟加载的。如果我这样做，我会收到错误，指出 Long: '' 的值是错误的。所以我的实体是:

@Lob @Basic(fetch = LAZY) String content;

如果我删除这个，一切都会好起来的。如何防止内容列每次都被加载并让Spring数据存储库正确搜索？

Answer 1

试试这个:在您的实体中创建一个仅接受必填字段的构造函数

public class KnowledgeBase{

//default constructor
public KnowledgeBase(){}

public KnowledgeBase(Long id,String link){
this.id=id;
this.link=link;
}

}

并在存储库的查询中使用此构造函数签名

 @Query(value = "SELECT new #{#entityName} (c.id as id,c.link as link) from #{#entityName} c "
            + " from knowledgebase c where content=?1", nativeQuery = true)
    List<KnowledgeBase> findRelevantRecordsWithoutContent(String searchString);