Cypher:使用Scala AnormCypher查找路径

Question

AnormCypher文档提供了一个如何使用Stream API检索数据的示例:http://anormcypher.org/

"访问返回查询结果的第一种方法是使用Stream API。

当你在任何Cypher语句上调用apply()时，你将收到CypherRow实例的惰性流，其中每一行都可以被视为一个字典:

 // Create Cypher query
 val allCountries = Cypher("start n=node(*) where n.type = 'Country' return n.code as code, n.name as name")
 // Transform the resulting Stream[CypherRow] to a List[(String,String)]
 val countries = allCountries.apply().map(row => 
   row[String]("code") -> row[String]("name")
 ).toList

我试图使用相同的方法来获取路径与以下Cypher查询:

MATCH p = (n {id: 'n5'})-[*]-(m) RETURN p;

然而，当运行这段代码时:

Cypher("MATCH p = (n {id: 'n5'})-[*]-(m) RETURN p;")().map {row  =>
  println(row[Option[org.anormcypher.NeoRelationship]]("p"))
}

我得到异常(见下文)。在这种情况下，如何从CypherRow获取路径信息?

 Exception in thread "main" java.lang.RuntimeException: TypeDoesNotMatch(Unexpected type while building a relationship)
    at org.anormcypher.MayErr$$anonfun$get$1.apply(Utils.scala:21)
    at org.anormcypher.MayErr$$anonfun$get$1.apply(Utils.scala:21)
    at scala.util.Either.fold(Either.scala:97)
    at org.anormcypher.MayErr.get(Utils.scala:21)
    at org.anormcypher.CypherRow$class.apply(AnormCypher.scala:303)
    at org.anormcypher.CypherResultRow.apply(AnormCypher.scala:309)
    at bigdata.test.n4j.Simple$$anonfun$main$1.apply(Simple.scala:31)
    at bigdata.test.n4j.Simple$$anonfun$main$1.apply(Simple.scala:29)
    at scala.collection.immutable.Stream.map(Stream.scala:376)
    at bigdata.test.n4j.Simple$.main(Simple.scala:29)

Answer 1

Cypher中的路径在2.0中发生了变化，因此您不能直接使用它们，因为它们不是集合。在AnormCypher中可能应该有一个新的路径类型，但现在你可以使用relationships()或nodes()路径。

例如，您可以这样做来提取关系:

Cypher("MATCH p = (n {id: 'n5'})-[*]-(m) RETURN relationships(p);")().map {row  =>
  println(row[Seq[NeoRelationship]]("relationships(p)"))
}