Neo4jClient System.NullReferenceException

Question

有时在 Neo4jClient 中我会收到此错误。我试图调查问题出在哪里，但我没有找到任何原因。有没有人有同样的问题或者可以帮助我？

谢谢

{"Message":"An error has occurred.","ExceptionMessage":"Object reference not set to an instance of an object.","ExceptionType":"System.NullReferenceException","StackTrace":" 在 Neo4jClient.GraphClient.Neo4jClient.IRawGraphClient.ExecuteGetCypherResults[TResult](CypherQuery 查询) in D:\temp17fa3\Neo4jClient.Shared\GraphClient.cs:line 919\r\n at Mandarim.Storage.Neo4j.Manager.ManagerBase1.GetNodesRelatedOrderBy(String match, String id, String relationNodeType, String propertyOrderBy, Int32 skip, Int32 take, Direction direction, Boolean distinct, Expression1 其中）在 P:\Desenvolvimento\branchs\builder-3.0\Mandarim.Storage.Neo4j\Manager\ManagerBase.cs:line 2105\r\n在 Mandarim.Storage.Neo4j.Manager.ManagerBase1.GetNodesRelatedOrderBy(String id, Labels labelin, Labels labelout, String relationTypes, String propertyOrderBy, Int32 skip, Int32 take, Boolean distinct, Expression1 where, Direction direction) in P:\Desenvolvimento\branchs\builder-3.0\Mandarim.Storage.Neo4j\Manager\ManagerBase.cs:line 900\r\n 在 Mandarim.Factory.Base.FactoryBase1.GetNodesRelatedOrderBy(String id, Labels labelin, Labels labelout, String relationTypes, String propertyOrderBy, Int32 skip, Int32 take, Boolean distinct, Expression1 where, Direction direction) in P:\Desenvolvimento\branchs\builder-3.0\Mandarim.Factory\Base\FactoryBase.cs:line 177\r\n at PackDocs.Services.Storage.MandarimStorageServices1.GetNodesRelatedOrderBy(String id, Labels labelin, Labels labelout, String propertyOrderBy, Int32 skip, Int32 take, Boolean distinct, Expression1 其中，Direction 方向，RelationTypes[] relationNodeType) in P:\Desenvolvimento\branchs\builder-3.0\Packdocs.Services.Storage\MandarimStorageServices.cs:line 292\r\n
在 Mandarim.PackDocs.Services.ManagerObjects.ManagerProject.GetProjects(Int32 skip, Int32 take, String orderby, CreatedState state) in P:\Desenvolvimento\branchs\builder-3.0\PackDocs.Services\ManagerObjects\ManagerProject.cs:行 116\r\n 在 PackDocs.OWIN.Services.Host.Controllers.ProjectsController.GetProjects(Int32 skip, Int32 take, String orderby, CreatedState state) in P:\Desenvolvimento\branchs\builder-3.0\Packdocs.OWIN.Services.Host\Controllers\v2\ProjectsController.cs:line 103\r\n at lambda_method(Closure , Object , Object[] )\r\n at System.Web.Http.Controllers.ReflectedHttpActionDescriptor.ActionExecutor.<>c__DisplayClass10.b__9(Object instance, Object[] methodParameters)\r\n 在 System.Web.Http.Controllers.ReflectedHttpActionDescriptor.ExecuteAsync(HttpControllerContext controllerContext, IDictionary`2 arguments, CancellationToken cancellationToken)\r\n--- 从先前抛出异常的位置开始的堆栈跟踪结束 ---\r\n at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)\r\n at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification（任务任务）\r\n 在 System.Web.Http.Controllers.ApiControllerActionInvoker.d__0.MoveNext()\r\n--- 从先前抛出异常的位置开始的堆栈跟踪结束 ---\r\n at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess（任务任务）\r\n 在 System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification（任务任务）\r\n 在 System.Web.Http.Controllers.ActionFilterResult.d__2.MoveNext()\r\n--- 从先前抛出异常的位置开始的堆栈跟踪结束 ---\r\n at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess（任务任务）\r\n 在 System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification（任务任务）\r\n 在 System.Web.Http.Filters.AuthorizationFilterAttribute.d__2.MoveNext()\r\n--- 从先前抛出异常的位置开始的堆栈跟踪结束 ---\r\n 在 System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess（任务任务）\r\n 在 System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification（任务任务)\r\n 在 System.Web.Http.Dispatcher.HttpControllerDispatcher.d__1.MoveNext()"}

更新

            ContainerBuilder _builder = new ContainerBuilder();

            _builder
            .Register<ITransactionalGraphClient>(context =>
            {
                try
                {
                    var neo4jUri = GetNeo4jSettingValue("neo4jUri");
                    var user = GetNeo4jSettingValue("neo4jUser");
                    var pwd = GetNeo4jSettingValue("neo4jPassword");
                    ITransactionalGraphClient graphClient = new GraphClient(new Uri(neo4jUri), user, pwd);
                    graphClient.Connect();
                    graphClient.JsonConverters.Add(new DictionaryConverter());
                    graphClient.JsonConverters.Add(new DateTimeConverter());
                    graphClient.JsonConverters.Add(new CommonDeserializerMethods());


                    return graphClient;
                }
                catch (Exception e)
                {
                    Trace.TraceError(e.ToString());
                    throw e;
                }
            }).SingleInstance();

            _container = _builder.Build();

获取实例

           try
            {
                _myGraphClient = _myGraphClient ?? AutofacNeo4j.Container.Resolve<ITransactionalGraphClient>();
                if (_myGraphClient != null && !_myGraphClient.IsConnected)
                    _myGraphClient.Connect();
                return _myGraphClient;
            }
            catch (Exception e)
            {
                Trace.TraceError(e.ToString());
                _myGraphClient = _myGraphClient ?? AutofacNeo4j.Container.Resolve<ITransactionalGraphClient>();
                _myGraphClient.Connect();
                return _myGraphClient;
            }

我的查询：

                     MyGraphClient.Cypher
                    .Match(match).Where((T a) => a.UUID == id)
                    .With("b")
                    .CurrentUser(CurrentUsername)
                    .WhereReadClause("b", GetDomainsClause("b"),       CurrentUsername, CurrentRole, direction)
                    .Return(b => b.As<T>()).Results;

第二个异常：

Neo4jClient.Transactions.TransactionManager.EnqueueCypherRequest(String commandDescription, IGraphClient graphClient, CypherQuery query) in D:\temp17fa3\Neo4jClient.Full\Transactions\TransactionManager.cs:line 229 在 Neo4jClient.GraphClient.PrepareCypherRequest[TResult]（CypherQuery 查询，IExecutionPolicy 策略）在 D:\temp17fa3\Neo4jClient.Shared\GraphClient.cs:line 871 在 Neo4jClient.GraphClient.d__881.MoveNext() in D:\temp17fa3\Neo4jClient.Shared\GraphClient.cs:line 967 --- End of stack trace from previous location where exception was thrown --- at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task) at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task) at System.Runtime.CompilerServices.TaskAwaiter1.GetResult() 在 Mandarim.Storage.Neo4j.Manager.ManagerBase`1.d__113.MoveNext() 中 P:\Desenvolvimento\branchs\builder-3.0\Mandarim.Storage.Neo4j\Manager\ManagerBase.cs:line 2067

Answer 1

当我们在这里使用异步 api 进行多事务处理时会出现问题。 Neo4jClient 代码上的 [TreadStartic] 不能很好地使用异步方法...所以我改为使用 AsyncLocal。

更多信息可以在这里获取：https://github.com/Readify/Neo4jClient/pull/209

Neo4jClient System.NullReferenceException

Neo4jClient System.NullReferenceException

neo4j

neo4jclient