如何使用Gremlin收集沿路径的所有顶点和边属性 [英] How to collect all vertex and edge properties along path, with Gremlin

问题描述

这是一个非常简单的查询：

Here's a really simple query:

g.V('customerId').out().path()

此的JSON输出是

{  
   "requestId":"96b26c1d-d032-2004-d36e-c700bd6db2a2",
   "status":{  
      "message":"",
      "code":200,
      "attributes":{  
         "@type":"g:Map",
         "@value":[  

         ]
      }
   },
   "result":{  
      "data":{  
         "@type":"g:List",
         "@value":[  
            {  
               "@type":"g:Path",
               "@value":{  
                  "labels":{  
                     "@type":"g:List",
                     "@value":[  
                        {  
                           "@type":"g:Set",
                           "@value":[  

                           ]
                        },
                        {  
                           "@type":"g:Set",
                           "@value":[  

                           ]
                        }
                     ]
                  },
                  "objects":{  
                     "@type":"g:List",
                     "@value":[  
                        {  
                           "@type":"g:Vertex",
                           "@value":{  
                              "id":"customerId",
                              "label":"customer"
                           }
                        },
                        {  
                           "@type":"g:Vertex",
                           "@value":{  
                              "id":"e:[e-mail]",
                              "label":"email"
                           }
                        }
                     ]
                  }
               }
            }
         ]
      },
      "meta":{  
         "@type":"g:Map",
         "@value":[  

         ]
      }
   }
}

现在，客户顶点还包含属性名称和年龄。我想了解的是，如何（如果可能的话）形成我的gremlin查询，以使其嵌套图内的顶点属性。请注意，当我只运行gV（ customerId）时，响应确实包含这些属性。

Now, a customer vertex also contains the property name and age. What I would like to understand, is how to (simply, if possible) form my gremlin query such that it nests of the vertex properties within the graph. Note that when I just run g.V("customerId"), the response does contain these properties.

推荐答案

您应始终始终准确指定您想要遍历返回的数据。即使是简单的事情，也是如此：

You should always specific exactly the data that you want returned in a traversal. Even for something as simple as:

g.V('customerId')

您应该更喜欢：

g.V('customerId').valueMap('name','age')

在SQL中，实际上可能没有什么不同不会这样做

It's really no different in SQL where you likely wouldn't do

SELECT * FROM customer

，而是

SELECT name, age FROM customer

对于您的问题，您只需要指定要返回的数据，因此使用 by（） 调制器，用于 path（）：

As for your question, you just need to specify the data you want back, so use the by() modulator for the path():

g.V('customerId').
  out().
  path().
    by(valueMap('name','age'))

当然您的 out（）也是客户，如果没有，只需添加第二个 by（）为此所需的字段。 by（）调制器以循环方式应用。如果您想使用稍微干净一点的JSON，可以改用 project（），例如：

That of course assumes your out() is also a "customer", if not, just add a second by() with the specific fields required for that. The by() modulators are applied in round-robin fashion. If you'd like a slightly cleaner bit of JSON to deal with you might instead use project() like:

g.V('customerId').
  out().
  path().
    by(project('name','age').
         by('name').
         by('age'))

那样会杀死 valueMap（）添加的嵌入列表，以便正确地考虑多个-properties。

as that will kill out the embedded lists that valueMap() adds in to properly account for multi-properties.

从TinkerPop 3.4.4开始，您还可以考虑 elementMap（）步骤，其中包括更多

As of TinkerPop 3.4.4, you would also consider elementMap()-step which includes more of the structure of the graph element.

gremlin> g.V().has('person','name','marko').elementMap()
==>[id:1,label:person,name:marko,age:29]
gremlin> g.V().has('person','name','marko').elementMap('name')
==>[id:1,label:person,name:marko]
gremlin> g.V().has('person','name','marko').properties('name').elementMap()
==>[id:0,key:name,value:marko]
gremlin> g.E(11).elementMap()
==>[id:11,label:created,IN:[id:3,label:software],OUT:[id:4,label:person],weight:0.4]

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