如何在Spring项目中使用ElasticSearch的NativeSearchQueryBuilder返回单个对象？

Question

我使用NativeSearchQueryBuilder形成查询，如下所示：

 String[] includeFields = new String[]{"idDl", "clientName"};
 String[] excludeFields = new String[]{"Address"};
 Query searchQuery = new NativeSearchQueryBuilder()
                .withQuery(matchQuery("idDl", idDl))
                .withSourceFilter(new FetchSourceFilter(includeFields, excludeFields))
                 .build();
return elasticsearchRestTemplate.queryForObject((StringQuery) searchQuery, User.class);

我想返回没有某些字段的单个对象，这是异常的堆栈跟踪：

java.lang.ClassCastException: org.springframework.data.elasticsearch.core.query.NativeSearchQuery cannot be cast to org.springframework.data.elasticsearch.core.query.StringQuery
at com.user.services.UserQueryServiceImpl.getUserById(UserQueryServiceImpl.java:37) ~[classes/:na]
at com.User.controllers.UserController.getFilteredUserById(UserController.java:100) ~[classes/:na]
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_231]
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:1.8.0_231]
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_231]
at java.lang.reflect.Method.invoke(Method.java:498) ~[na:1.8.0_231]
at org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:190) ~[spring-web-5.2.5.RELEASE.jar:5.2.5.RELEASE]
at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:138) ~[spring-web-5.2.5.RELEASE.jar:5.2.5.RELEASE]
at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:105) ~[spring-webmvc-5.2.5.RELEASE.jar:5.2.5.RELEASE]
at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:879) ~[spring-webmvc-5.2.5.RELEASE.jar:5.2.5.RELEASE]
at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:793) ~[spring-webmvc-5.2.5.RELEASE.jar:5.2.5.RELEASE]
at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:87) ~[spring-webmvc-5.2.5.RELEASE.jar:5.2.5.RELEASE]
at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:1040) ~[spring-webmvc-5.2.5.RELEASE.jar:5.2.5.RELEASE]
at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:943) ~[spring-webmvc-5.2.5.RELEASE.jar:5.2.5.RELEASE]
at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:1006) ~[spring-webmvc-5.2.5.RELEASE.jar:5.2.5.RELEASE]
at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:898) ~[spring-webmvc-5.2.5.RELEASE.jar:5.2.5.RELEASE]
at javax.servlet.http.HttpServlet.service(HttpServlet.java:634) ~[tomcat-embed-core-9.0.33.jar:9.0.33]
at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:883) ~[spring-webmvc-5.2.5.RELEASE.jar:5.2.5.RELEASE]
at javax.servlet.http.HttpServlet.service(HttpServlet.java:741) ~[tomcat-embed-core-9.0.33.jar:9.0.33]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:231) ~[tomcat-embed-core-9.0.33.jar:9.0.33]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.33.jar:9.0.33]

Answer 1

首先，不推荐使用queryForObject，您应该使用searchOne（）。至于你的错误：

创建一个NativeSearchQuery，将其分配给类型为Query的变量searchQuery；没关系。但为什么要将其转换为StringQuery？

NativeSearchQuery和StringQuery都实现了查询，所以只需传递查询实例：

return elasticsearchRestTemplate.queryForObject(searchQuery, User.class)

编辑Spring Data Elasticsearch 3.2. x：

你应该用

<T> List<T> queryForList(SearchQuery query, Class<T> clazz);

与该版本一样，仍然有NativeSearchQuery实现的SearchQuery接口。从返回的列表中，检查是否包含任何元素，然后使用第一个元素。