Question

我想在其C＃等价物中获得以下查询：

match(p:Person)-[r1:HAS]->(s:Shelf) 
optional match(s)-[r2:CONTAINS]->(l:Link) return p,s,l 
order by r2.time_modified;

我最初想过这个，但它不起作用：

var result = await this._graphClient.Cypher
                 .Match("(person:Person { person_id: {personId}})-[r1:HAS]->(shelf:Shelf)")
                 .OptionalMatch("(shelf)-[r2:CONTAINS]->(link:Link)")
                 .WithParams(new { personId = personId })
                 .Return((shelf, link) => new 
                  {
                     Shelf = shelf.As<Shelf>(),
                     Links = link.CollectAs<Link>()
                  })
                 .OrderBy("r2.time_modified")
                 .ResultsAsync;

我得到以下例外，即r2未定义

r2未定义...... ＆＃34; ORDER BY r2.time_modified＆＃34;

我对使用Neo4jClient C＃驱动程序比较陌生。任何人都可以帮助我并向我解释发生了什么？我也想知道如何解决这个问题。

这是堆栈跟踪：

at System.Threading.Tasks.Task.ThrowIfExceptional（Boolean includeTaskCanceledExceptions）在System.Threading.Tasks.Task 1.GetResultCore(Boolean waitCompletionNotification) at System.Threading.Tasks.Task 1.get_Result（）在Neo4jClient.GraphClient。＆lt;＆gt; c__85 1.<PrepareCypherRequest>b__85_1(Task 1回复）在D：\ temp \ d298ce3 \ Neo4jClient \ GraphClient.cs：第961行在System.Threading.Tasks.ContinuationResultTaskFromResultTask 2.InnerInvoke() at System.Threading.Tasks.Task.Execute() --- 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.ConfiguredTaskAwaitable 1.ConfiguredTaskAwaiter.GetResult（）在Neo4jClient.GraphClient.d__87 1.MoveNext() in D:\temp\d298ce3\Neo4jClient\GraphClient.cs:line 1022 --- 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.TaskAwaiter 1.GetResult（） at .... Repository.Neo4jRepository.d__23.MoveNext（）在C：\ Users \ Williams \ documents \ visual studio 2015 \ Projects ... \ Repository \ Neo4jRepository.cs：358行

Answer 1

由于您在Return声明中执行了r2，var query = gc.Cypher .Match("(p:Person { person_id: 'a'})-[r1:HAS]->(s:Shelf)") .OptionalMatch("(s)-[r2:CONTAINS]->(l:Link)") .With("p,s,l") .OrderBy("r2.time_modified") .Return((p,s,l) => new { Person = p.As<Person>(), Shelf = s.As<Shelf>(), Links = l.CollectAs<Link>() }); var res = query.Results;已不再存在。

您需要在返回前订购：

{{1}}

Answer 2

您需要先返回r2.time_modified，然后才能通过它订购结果。

match(p:Person)-[r1:HAS]->(s:Shelf) 
optional match(s)-[r2:CONTAINS]->(l:Link) 
return p,s,l,r2.time_modified
order by r2.time_modified;

如果返回，您可以将其用于ORDER BY。

[编辑]

未测试：

var result = await this._graphClient.Cypher
                 .Match("(person:Person { person_id: {personId}})-[r1:HAS]->(shelf:Shelf)")
                 .OptionalMatch("(shelf)-[r2:CONTAINS]->(link:Link)")
                 .WithParams(new { personId = personId })
                 .Return((shelf, link, r2) => new 
                  {
                     Shelf = shelf.As<Shelf>(),
                     Links = link.CollectAs<Link>()
                  })
                 .OrderBy("r2.time_modified")
                 .ResultsAsync;

使用Neo4jClient C＃按关系属性排序

2 个答案: