图表 - 显示朋友的朋友（以及 1 级普通朋友）

Question

我找到了一个“朋友的朋友”遍历查询，可以满足我获取朋友的朋友的基本需求（friends of friend Query in ArangoDB 3.0）。我对其稍作修改，使其与文档中的“Knows_Graph”示例一起使用，并且我添加了一些额外的人员 (https://docs.arangodb.com/3.1/Manual/Graphs/)

我的查询使用 Dave 作为起点，并通过 Bob 和 Lucy 查找他的二年级朋友。该脚本工作正常，但我也希望它在查询结果中包含 1 级朋友（鲍勃和露西）。我可以通过将最小深度设置为 1 来做到这一点，但是如果我这样做，我不会区分 Bob 和 Lucy 的深度（参见 json 输出），所以我将无法在更大的图表上判断谁是 1 度和谁是二级

最小深度为 2 的示例代码

LET person = DOCUMENT("persons/@persons/dave")
LET foaf = (
  FOR v IN 2..2 ANY person knows      
    RETURN v
)
RETURN MERGE(person, { foaf } )

示例使用“knows”边集合和“person”集合

如果我的最小深度为 1，最大深度为 2，那么这里是 json 输出。如您所见，bob 和 lucy 显示在与其他人相同的集合级别上。我想找到一种方法以某种方式将它们显示为第一级，而不会使查询过于复杂或导致性能问题。

[
  {
    "_id": "persons/dave",
    "_key": "dave",
    "_rev": "_U7wRsJG--_",
    "name": "Dave",
    "foaf": [
      {
        "_key": "lucy",
        "_id": "persons/lucy",
        "_rev": "_U8--wPq---",
        "name": "Lucy"
      },
      {
        "_key": "henry",
        "_id": "persons/henry",
        "_rev": "_U8-_FNa---",
        "name": "Henry"
      },
      {
        "_key": "bob",
        "_id": "persons/bob",
        "_rev": "_U7wRsJC--_",
        "name": "Bob"
      },
      {
        "_key": "charlie",
        "_id": "persons/charlie",
        "_rev": "_U7wRsJG---",
        "name": "Charlie"
      },
      {
        "_key": "alice",
        "_id": "persons/alice",
        "_rev": "_U7wRsJC---",
        "name": "Alice"
      },
      {
        "_key": "eve",
        "_id": "persons/eve",
        "_rev": "_U7wRsJG--A",
        "name": "Eve"
      }
    ]
  }
]

Answer 1

通过以下查询，您可以获得每个朋友的深度信息。

LET person = DOCUMENT("persons/@persons/dave")
LET foaf = (
  FOR v, e, p IN 1..2 ANY person knows      
    RETURN {v, depth: LENGTH(p.edges)}
)
RETURN MERGE(person, { foaf } )

输出应如下所示：

[
  {
    "_id": "persons/dave",
    "_key": "dave",
    "_rev": "_U8e0Ube---",
    "foaf": [
      {
        "v": {
          "_key": "lucy",
          "_id": "persons/lucy",
          "_rev": "_U8e0Y2u---"
        },
        "depth": 1
      },
      {
        "v": {
          "_key": "bob",
          "_id": "persons/bob",
          "_rev": "_U8ezwCm---"
        },
        "depth": 1
      },
      {
        "v": {
          "_key": "charlie",
          "_id": "persons/charlie",
          "_rev": "_U8e0-Oe---"
        },
        "depth": 2
      },
      {
        "v": {
          "_key": "eve",
          "_id": "persons/eve",
          "_rev": "_U8e0loy---"
        },
        "depth": 2
      },
      {
        "v": {
          "_key": "alice",
          "_id": "persons/alice",
          "_rev": "_U8e0ptu---"
        },
        "depth": 2
      }
    ]
  }
]

如果您想将各个深度的朋友分组在一起，您的查询可能如下所示：

LET person = DOCUMENT("persons/@persons/dave")
LET foaf = (
  FOR v, e, p IN 1..2 ANY person knows      
    COLLECT depth = LENGTH(p.edges) INTO s KEEP v
    RETURN {depth, foaf: s[*].v}
)
RETURN MERGE(person, { foaf } )

输出应如下所示：

[
  {
    "_id": "persons/dave",
    "_key": "dave",
    "_rev": "_U8e0Ube---",
    "foaf": [
      {
        "depth": 1,
        "foaf": [
          {
            "_key": "lucy",
            "_id": "persons/lucy",
            "_rev": "_U8e0Y2u---"
          },
          {
            "_key": "bob",
            "_id": "persons/bob",
            "_rev": "_U8ezwCm---"
          }
        ]
      },
      {
        "depth": 2,
        "foaf": [
          {
            "_key": "charlie",
            "_id": "persons/charlie",
            "_rev": "_U8e0-Oe---"
          },
          {
            "_key": "eve",
            "_id": "persons/eve",
            "_rev": "_U8e0loy---"
          },
          {
            "_key": "alice",
            "_id": "persons/alice",
            "_rev": "_U8e0ptu---"
          }
        ]
      }
    ]
  }
]

更新

如果您需要有关人与人之间关系的更多信息，您可以返回路径而不是顶点。路径 (p) 包括所有访问的边（知道关系）和所有顶点（人）。 有关 AQL 遍历语法的更多信息：请参阅docs。

LET person = DOCUMENT("persons/@persons/dave")
LET foaf = (
  FOR v, e, p IN 1..2 ANY person knows      
    COLLECT depth = LENGTH(p.edges) INTO s KEEP p
    RETURN {depth, foaf: s[*].p}
)
RETURN MERGE(person, { foaf } )