Question

我是Neo4j场景的新手，但在尝试创建播放列表和歌曲之间的关系时，我收到以下C＃错误：

An unhandled exception of type 'System.NullReferenceException' occurred in Neo4jClient.dll

Additional information: Object reference not set to an instance of an object.

C＃代码：

client.Cypher
    .Match("(song1:Song)", "(playlist1:Playlist)")
    .Where((Song song1) => song1.Name == newSong.Name)
    .AndWhere((Playlist playlist1) => playlist1.Name == newPlaylist.Name)
    .Create("(playlist1)-[r:CONTAINS_SONG]->(song1)")
    .ExecuteWithoutResults();

对象newSong和newPlaylist用来自文件的数据播种，并且已存在于Neo4j数据库中。使用实时调试器时，我看到newSong.Name等于“在她眼中再见”，newPlaylist.Name等于“Adam Country”。这些值都存在于Neo4j数据库中（如下）。使用.Query.QueryText也会产生相同的错误。我正在使用neo4j-community-3.0.0-M03和Neo4jClient 1.1.0.28。

我创建了自己的查询，但我觉得C＃代码和正在输出的实际查询之间存在脱节。以下作品：

MATCH (song1:Song),(playlist1:Playlist)
WHERE song1.Name = 'Goodbye In Her Eyes' AND playlist1.Name = 'Adam Country'
CREATE (playlist1)-[r:CONTAINS_SONG]->(song1)

Neo4j浏览器文本输出：

+==============================+
|n                             |
+==============================+
|FullName: Adam Country.txt    |
|Name: Adam Country            |
+------------------------------+
|Artist: Zac Brown Band        |
|FullName: Goodbye In Her Eyes |
|Name: Goodbye In Her Eyes     |
+------------------------------+

我的C＃代码应该如何实现这种关系？

[Playlist "Adam Country"] CONTAINS_SONG [Song "Goodbye In Her Eyes"]

Answer 1

如果初始化newSong和newPlaylist，最可能的解释是客户端未初始化。您是否创建了GraphClient实例，然后调用Connect？

var client = new GraphClient(new Uri("http://localhost:7474/db/data"));
client.Connect();

如何使用C＃Neo4jClient在两个节点之间创建关系？

1 个答案: