Question

我对MongoDB中的级联有疑问；所以。我的项目基于Java 10和Spring Boot 2.0.5和Lombok。我已经创建了CascadeSave事件侦听器，就是这样

public class CascadeSaveMongoEventListener extends AbstractMongoEventListener {

@Autowired
private MongoOperations mongoOperations;

@Override
public void onBeforeConvert(BeforeConvertEvent event) {

    Object source = event.getSource();
    ReflectionUtils.doWithFields(source.getClass(), field -> {
        ReflectionUtils.makeAccessible(field);
        if (field.isAnnotationPresent(DBRef.class) && field.isAnnotationPresent(CascadeSave.class)) {
            Object fieldValue = field.get(source);
            if (fieldValue instanceof Collection<?>) {
                Collection collection = (Collection<?>) fieldValue;
                for (Object o : collection) {
                    mongoOperations.save(o);
                }
            } else {
                mongoOperations.save(fieldValue);
            }
        }
    });
}

}

事件监听器也包含在mongo配置中，如下所示：

@Bean
public CascadeSaveMongoEventListener cascadingMongoEventListener() {
    return new CascadeSaveMongoEventListener();
}

域类的外观如下：

@Data
@AllArgsConstructor
@NoArgsConstructor
@Document
public class Article {

    @Id
    private String id;

    @DBRef(lazy = true)
    @CascadeSave
    private List<Comment> comments;
}

@Data
@AllArgsConstructor
@NoArgsConstructor
@Document
public class Comment {

    @Id
    private String id;
    private String text;

}

问题是保存后，我通过Mongo Compass看了一下数据库，Article.comments是null的集合，但是注释正确地保存在单独的集合中。问题是什么？谢谢！

Java MongoDB级联异常

0 个答案: