Spring data elasticsearch:在POJO接口类上使用@Document注释不起作用

Question

我正在将一个应用程序迁移到最新的spring-boot版本(使用2.5.4版本的maven spring-boot-dependencies)。

我有一个名为Customer的接口，并且我有该接口的两个实现(BusinessCustomer,PrivateCustomer)

这三个类的注释如下:

@Document(indexName = "customers", type = "customer")
@JsonTypeInfo(
use = JsonTypeInfo.Id.NAME,
include = JsonTypeInfo.As.EXISTING_PROPERTY,
property = "customerType"
)
@JsonSubTypes({
@JsonSubTypes.Type(value = BusinessCustomer.class, name = "BUSINESS_CUSTOMER"),
@JsonSubTypes.Type(value = PrivateCustomer.class, name = "PRIVATE_CUSTOMER")
})
public interface Customer {

@JsonIgnoreProperties(ignoreUnknown = true)
@JsonTypeInfo(
use = JsonTypeInfo.Id.NAME,
include = JsonTypeInfo.As.EXISTING_PROPERTY,
property = "customerType",
defaultImpl = BusinessCustomer.class
)
@Entity
@Document(indexName = "customers", type = "customer")
public class BusinessCustomer implements Serializable, Customer, Cloneable {

@JsonIgnoreProperties(ignoreUnknown = true)
@JsonTypeInfo(
use = JsonTypeInfo.Id.NAME,
include = JsonTypeInfo.As.EXISTING_PROPERTY,
property = "customerType",
defaultImpl = PrivateCustomer.class
)
@Entity
@Document(indexName = "customers", type = "customer")
public class PrivateCustomer implements Serializable, Customer, Cloneable {

查询索引"客户";我曾经有这样的代码:

elasticsearchOperations.count(query, Customer.class);

但是这已经不起作用了。我在运行时得到一个错误:

Servlet.service() for servlet [dispatcherServlet] in context with path [] threw exception [Request processing failed; nested exception is org.springframework.data.mapping.model.MappingInstantiationException: Failed to instantiate Customer using constructor NO_CONSTRUCTOR with arguments ] with root cause org.springframework.beans.BeanInstantiationException: Failed to instantiate [Customer]: Specified class is an interface

是不可能有两个不同的类在同一个索引像这样吗?现在是否要以某种方式使用ElasticsearchCustomConversions ?

Answer 1

Spring Data Elasticsearch中的MappingElasticsearchConverter不能在接口上工作，而是依赖于在实体类上设置的@Document和@Field注释。

所有Spring Data模块——不仅仅是Spring Data Elasticsearch——都使用PersistentEntity的概念，这是关于要存储的类的元信息。PersistentPropertys，这是关于类属性的元信息。对于Spring Data Elasticsearch，这是关于Elasticsearch中字段名的信息，它是type，日期格式等信息

带@Document注释的类与索引相关联。从版本7开始，Elasticsearch不再支持在一个索引中包含多个类型。

所以你应该把不同的实体存储在两个索引中:

@Document(indexName="business-customers")
class BusinessCustomer {
// ...
}
@Document(indexName="private-customers")
class PrivateCustomer {
// ...
}

在一次调用中搜索这两个索引并返回不同的数据是可能的，我写了一篇关于如何做到这一点的博客文章(https://www.sothawo.com/2021/05/reading-different-entities-from-multiple-indices-with-one-call-using-spring-data-elasticsearch/)。