Question

使用我有的快速入门示例：

[{
  "id": "thomas",
  "label": "person",
  "type": "vertex",
  "outE": {
    "knows": [
      {
        "id": "edd08c25-cd6d-43e6-ad10-e1806f63cb90",
        "inV": "mary"
      },
      {
        "id": "e30693c4-019c-42fc-8968-3b6cd37fb279",
        "inV": "ben"
      }
    ]
  },
  "properties": {
    "firstName": [
      {
        "id": "3c401844-d30a-4046-a833-3f378ee52a30",
        "value": "Thomas"
      }
    ],
    "age": [
      {
        "id": "1cacf839-daa3-415f-8930-f4bedd15f803",
        "value": 44
      }
    ]
  }
},{
  "id": "mary",
  "label": "person",
  "type": "vertex",
  "inE": {
    "knows": [
      {
        "id": "edd08c25-cd6d-43e6-ad10-e1806f63cb90",
        "outV": "thomas"
      }
    ]
  },
  "properties": {
    "firstName": [
      {
        "id": "c8edabe7-10d5-4ef9-922b-4e6382c7d902",
        "value": "Mary"
      }
    ],
    "lastName": [
      {
        "id": "64f60649-278d-40d5-a511-b28970facc1d",
        "value": "Andersen"
      }
    ],
    "age": [
      {
        "id": "d8bd7758-baf0-4f5f-bd07-fa96d125fcd8",
        "value": 39
      }
    ]
  }
},{
  "id": "ben",
  "label": "person",
  "type": "vertex",
  "inE": {
    "knows": [
      {
        "id": "e30693c4-019c-42fc-8968-3b6cd37fb279",
        "outV": "thomas"
      }
    ]
  },
  "outE": {
    "knows": [
      {
        "id": "f8f136b0-d698-49d9-bb0a-f6291454d99a",
        "inV": "robin"
      }
    ]
  },
  "properties": {
    "firstName": [
      {
        "id": "2e0e52ac-4890-42bc-bc9e-0594c093d72c",
        "value": "Ben"
      }
    ],
    "lastName": [
      {
        "id": "b0367dd4-e559-4421-9e92-bdae80e41d0f",
        "value": "Miller"
      }
    ]
  }
},{
  "id": "robin",
  "label": "person",
  "type": "vertex",
  "inE": {
    "knows": [
      {
        "id": "f8f136b0-d698-49d9-bb0a-f6291454d99a",
        "outV": "ben"
      }
    ]
  },
  "properties": {
    "firstName": [
      {
        "id": "3f9edd99-09ab-40cb-99e7-8ef280618aae",
        "value": "Robin"
      }
    ],
    "lastName": [
      {
        "id": "76327942-3fcc-46a7-9ebd-a8df1141ec57",
        "value": "Wakefield"
      }
    ]
  }
}]

当我尝试按年龄排序时，

g.V().hasLabel('person').order().by('age', decr)

发生此异常：

Gremlin查询执行错误：订单：下一步：订单提供的遍历或属性名称未映射到值。

System.InvalidOperationException: Failed to compare two elements in the array. ---> Microsoft.Azure.Graphs.Common.GraphRuntimeException: Gremlin Query Execution Error: Order: Next: The provided traversal or property name of Order does not map to a value.
   at Microsoft.Azure.Graphs.Runtime.Operators.OrderOperator.<ComputeNextRecordAsync>b__5_0(RawRecord x, RawRecord y)
   at System.Collections.Generic.ArraySortHelper`1.InsertionSort(T[] keys, Int32 lo, Int32 hi, IComparer`1 comparer)
   at System.Collections.Generic.ArraySortHelper`1.IntrospectiveSort(T[] keys, Int32 left, Int32 length, IComparer`1 comparer)
   at System.Collections.Generic.ArraySortHelper`1.Sort(T[] keys, Int32 index, Int32 length, IComparer`1 comparer)
   --- End of inner exception stack trace ---
   at System.Collections.Generic.ArraySortHelper`1.Sort(T[] keys, Int32 index, Int32 length, IComparer`1 comparer)
   at System.Array.Sort[T](T[] array, Int32 index, Int32 length, IComparer`1 comparer)
   at System.Collections.Generic.List`1.Sort(Comparison`1 comparison)
   at Microsoft.Azure.Graphs.Runtime.Operators.OrderOperator.<ComputeNextRecordAsync>d__5.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at Microsoft.Azure.Graphs.Runtime.Operators.GraphExecutionOperator.<NextAsync>d__9.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at Microsoft.Azure.Graphs.Runtime.TableValuedFunction.<ComputeNextRecordAsync>d__4.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at Microsoft.Azure.Graphs.Runtime.Operators.GraphExecutionOperator.<NextAsync>d__9.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at Microsoft.Azure.Graphs.Runtime.Operators.ProjectOperator.<ComputeNextRecordAsync>d__4.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at Microsoft.Azure.Graphs.Runtime.Operators.GraphExecutionOperator.<NextAsync>d__9.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at Microsoft.Azure.Graphs.GraphTraversal.GraphTraversalIterator.<CurrentOperatorNextAsync>d__17.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at Microsoft.Azure.Graphs.GraphTraversal.GraphTraversalIterator.<MoveNextAsync>d__7.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at Microsoft.Azure.Graphs.GraphTraversal.<MoveNextAsync>d__17.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at Microsoft.Azure.Graphs.GremlinDocumentQuery`1.<ExecuteNextAsync>d__15`1.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at Microsoft.Azure.Graphs.GremlinDocumentQuery`1.<ExecuteNextAsync>d__14.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at Microsoft.Azure.Documents.Portal.PlatformProxy.Graph.Controllers.GremlinQueriesController.<SubmitQueryAsync>d__6.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at Microsoft.Azure.Documents.Portal.PlatformProxy.Graph.Controllers.GremlinQueriesController.<Post>d__0.MoveNext()

如何按年龄订购，因为并非所有Vertex都设置了年龄属性？

Answer 1

只需过滤掉没有DIV属性的顶点：

age

所以在你的情况下：

gremlin> g.V().order().by('age', decr)
The property does not exist as the key has no associated value for the provided element: v[3]:age
Type ':help' or ':h' for help.
Display stack trace? [yN]n
gremlin> g.V().has('age').order().by('age', decr)
==>v[6]
==>v[4]
==>v[1]
==>v[2]