SDN 4：java.lang.ClassCastException：java.util.LinkedHashMap 无法转换为 [实体节点]

Question

使用 SDN4 SNAPSHOT 构建时出现另一个问题。在尝试使用以 @QueryResult 注释的接口作为从查询返回结果的方式时，我似乎得到了一个 LinkedHashMap 异常。

这可能与前面提到的 Iterables 问题有关，也可能无关 post：

堆栈跟踪：

org.springframework.web.util.NestedServletException: Request processing failed; nested exception is java.lang.ClassCastException: java.util.LinkedHashMap cannot be cast to com.example.server.model.neo4j.node.Item
    at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:981)
    at org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:871)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:648)
    at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:845)
    at org.springframework.test.web.servlet.TestDispatcherServlet.service(TestDispatcherServlet.java:65)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
    at org.springframework.mock.web.MockFilterChain$ServletFilterProxy.doFilter(MockFilterChain.java:167)
    at org.springframework.mock.web.MockFilterChain.doFilter(MockFilterChain.java:134)
    at org.springframework.test.web.servlet.MockMvc.perform(MockMvc.java:144)
    at com.example.server.test.integration.IntegrationTestBase.makeMvcCall(IntegrationTestBase.java:54)
    at com.example.server.test.integration.controller.api.itemdiscovery.TestSearchItemsWithSuggestions.testSearchItemsWithSuggestions(TestSearchItemsWithSuggestions.java:49)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:606)
    at org.junit.runners.model.FrameworkMethod.runReflectiveCall(FrameworkMethod.java:50)
    at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
    at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:47)
    at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)
    at org.junit.internal.runners.statements.RunBefores.evaluate(RunBefores.java:26)
    at org.springframework.test.context.junit4.statements.RunBeforeTestMethodCallbacks.evaluate(RunBeforeTestMethodCallbacks.java:74)
    at org.springframework.test.context.junit4.statements.RunAfterTestMethodCallbacks.evaluate(RunAfterTestMethodCallbacks.java:85)
    at org.springframework.test.context.junit4.statements.SpringRepeat.evaluate(SpringRepeat.java:86)
    at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:325)
    at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.runChild(SpringJUnit4ClassRunner.java:243)
    at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.runChild(SpringJUnit4ClassRunner.java:88)
    at org.junit.runners.ParentRunner.run(ParentRunner.java:290)
    at org.junit.runners.ParentRunner.schedule(ParentRunner.java:71)
    at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288)
    at org.junit.runners.ParentRunner.access[=12=]0(ParentRunner.java:58)
    at org.junit.runners.ParentRunner.evaluate(ParentRunner.java:268)
    at org.springframework.test.context.junit4.statements.RunBeforeTestClassCallbacks.evaluate(RunBeforeTestClassCallbacks.java:61)
    at org.springframework.test.context.junit4.statements.RunAfterTestClassCallbacks.evaluate(RunAfterTestClassCallbacks.java:70)
    at org.junit.runners.ParentRunner.run(ParentRunner.java:363)
    at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.run(SpringJUnit4ClassRunner.java:182)
    at org.junit.runners.Suite.runChild(Suite.java:128)
    at org.junit.runners.Suite.runChild(Suite.java:27)
    at org.junit.runners.ParentRunner.run(ParentRunner.java:290)
    at org.junit.runners.ParentRunner.schedule(ParentRunner.java:71)
    at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288)
    at org.junit.runners.ParentRunner.access[=12=]0(ParentRunner.java:58)
    at org.junit.runners.ParentRunner.evaluate(ParentRunner.java:268)
    at org.junit.runners.ParentRunner.run(ParentRunner.java:363)
    at org.junit.runners.Suite.runChild(Suite.java:128)
    at org.junit.runners.Suite.runChild(Suite.java:27)
    at org.junit.runners.ParentRunner.run(ParentRunner.java:290)
    at org.junit.runners.ParentRunner.schedule(ParentRunner.java:71)
    at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288)
    at org.junit.runners.ParentRunner.access[=12=]0(ParentRunner.java:58)
    at org.junit.runners.ParentRunner.evaluate(ParentRunner.java:268)
    at org.junit.runners.ParentRunner.run(ParentRunner.java:363)
    at org.junit.runners.Suite.runChild(Suite.java:128)
    at org.junit.runners.Suite.runChild(Suite.java:27)
    at org.junit.runners.ParentRunner.run(ParentRunner.java:290)
    at org.junit.runners.ParentRunner.schedule(ParentRunner.java:71)
    at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288)
    at org.junit.runners.ParentRunner.access[=12=]0(ParentRunner.java:58)
    at org.junit.runners.ParentRunner.evaluate(ParentRunner.java:268)
    at org.junit.runners.ParentRunner.run(ParentRunner.java:363)
    at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:50)
    at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:38)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:459)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:675)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:382)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:192)
Caused by: java.lang.ClassCastException: java.util.LinkedHashMap cannot be cast to com.example.server.model.neo4j.node.Item
    at com.sun.proxy.$Proxy178.getItem(Unknown Source)
    at com.example.server.controller.api.ItemDiscoveryController.searchItemsWithSuggestions(ItemDiscoveryController.java:150)
    at com.example.server.controller.api.ItemDiscoveryController$$FastClassBySpringCGLIB$$fae06b6a.invoke(<generated>)
    at org.springframework.cglib.proxy.MethodProxy.invoke(MethodProxy.java:204)
    at org.springframework.aop.framework.CglibAopProxy$CglibMethodInvocation.invokeJoinpoint(CglibAopProxy.java:717)
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:157)
    at org.springframework.transaction.interceptor.TransactionInterceptor.proceedWithInvocation(TransactionInterceptor.java:99)
    at org.springframework.transaction.interceptor.TransactionAspectSupport.invokeWithinTransaction(TransactionAspectSupport.java:281)
    at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:96)
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179)
    at org.springframework.aop.framework.CglibAopProxy$DynamicAdvisedInterceptor.intercept(CglibAopProxy.java:653)
    at com.example.server.controller.api.ItemDiscoveryController$$EnhancerBySpringCGLIB$54cd8.searchItemsWithSuggestions(<generated>)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:606)
    at org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:221)
    at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:137)
    at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:111)
    at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandleMethod(RequestMappingHandlerAdapter.java:799)
    at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:728)
    at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:85)
    at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:959)
    at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:893)
    at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:969)
    ... 64 more

代码（在 searchItemsWithSuggestions 方法中）：

List<ItemWithCount> itemAndPopularityList = IteratorUtil.asList(itemRepository.findPopularItemsPersonDoesNotHave(params.getPersonId(), NUM_ITEMS_TO_RETURN));

for(ItemWithCount itemAndPopularity : itemAndPopularityList) {
    Item item = itemAndPopularity.getItem(); // Error here
    // More code here.
}

查询：

@Query("MATCH (person:Person {uuid:{personUuid}}), (otherperson:Person)-[rel:HAS_ITEM]->(item:Item) "
        + "WHERE NOT (person)-[:HAS_ITEM]->(item) "
        + "RETURN DISTINCT item, COUNT(rel) "
        + "ORDER BY COUNT(rel) DESC, item.name "
        + "LIMIT {limit}")
Iterable<ItemWithCount> findPopularItemsPersonDoesNotHave(@Param("personUuid") String personUuid,
        @Param("limit") int limit);

ItemWithCount 接口:

@QueryResult
public interface ItemWithCount {
    @ResultColumn("item")
    Item getItem();

    @ResultColumn("COUNT(rel))")
    Long getCount();
}

Answer 1

映射到 @QueryResult 和 @ResultColumn 中的实体在 SDN 4 中尚不支持。您需要 return 项目的 ID，并使用存储库、会话或模板加载它。查询结果的示例可以在这里找到：

存储库：https://github.com/spring-projects/spring-data-neo4j/blob/4.0.x/spring-data-neo4j/src/test/java/org/springframework/data/neo4j/examples/movies/repo/UserRepository.java

查询结果：https://github.com/spring-projects/spring-data-neo4j/blob/4.0.x/spring-data-neo4j/src/test/java/org/springframework/data/neo4j/examples/movies/domain/queryresult/UserQueryResult.java

SDN 4：java.lang.ClassCastException：java.util.LinkedHashMap 无法转换为 [实体节点]

SDN4: java.lang.ClassCastException: java.util.LinkedHashMap cannot be cast to [EntityNode]

neo4j

spring-data-neo4j-4