Neo4j客户端与返回一起"CASE WHEN"

Question

我试图弄清楚如何做这样的事情(简化(：

RETURN CASE WHEN groups IS NOT NULL THEN collect(groups) ELSE NULL END

在 C# 中使用 Neo4jClient。我试过这个：

.Return((groups) => new
{
Board = parentBoard.As<Board>(),
Groups = Return.As<Groups>("CASE WHEN groups IS NOT NULL THEN collect(groups) ELSE NULL END")
});

但它会引发异常。我找不到有关如何使用 neo4jclient 正确执行此操作的任何信息。我这样做的方式似乎确实返回了一个有效的 json 响应，但 neo4jclient 显然无法读取它。因此，我怀疑neo4jclient希望以其他方式完成此操作？基本上，如果groups为 null，我想返回 null，因为 collect(NULL( 不会只返回 null。有什么想法吗？

System.ArgumentException: Neo4j returned a valid response, however Neo4jClient was unable to deserialize into the object structure you supplied.
First, try and review the exception below to work out what broke.                                                                          
If it's not obvious, you can ask for help at http://stackoverflow.com/questions/tagged/neo4jclient                                          
Include the full text of this exception, including this message, the stack trace, and all of the inner exception details.                  
Include the full type definition of <>f__AnonymousType2`2[[Kolan.Models.Board, Kolan, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null],[Kolan.Models.Groups, Kolan, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null]].
Include this raw JSON, with any sensitive values replaced with non-sensitive equivalents:                                                   
{"columns":["Board","Groups"],"data":[[{"extensions":{},"metadata":{"id":370,"labels":["Board"]},"paged_traverse":"http://localhost:7474/db/data/node/370/paged/traverse/{returnType}{?pageSize,leaseTime}","outgoing_relationships":"http://localhost:7474/db/data/node/370/relationshi
ps/out","outgoing_typed_relationships":"http://localhost:7474/db/data/node/370/relationships/out/{-list|&|types}","create_relationship":"http://localhost:7474/db/data/node/370/relationships","labels":"http://localhost:7474/db/data/node/370/labels","traverse":"http://localhost:747
4/db/data/node/370/traverse/{returnType}","all_relationships":"http://localhost:7474/db/data/node/370/relationships/all","all_typed_relationships":"http://localhost:7474/db/data/node/370/relationships/all/{-list|&|types}","property":"http://localhost:7474/db/data/node/370/propert
ies/{key}","self":"http://localhost:7474/db/data/node/370","incoming_relationships":"http://localhost:7474/db/data/node/370/relationships/in","properties":"http://localhost:7474/db/data/node/370/properties","incoming_typed_relationships":"http://localhost:7474/db/data/node/370/re
lationships/in/{-list|&|types}","data":{"name":"empty","description":"An empty board.","id":"Mrw7M8myg"}},[{"boards":[],"group":null}]]]} (Parameter 'content')
---> System.ArgumentException: Accessed JArray values with invalid key value: "data". Int32 array index expected.                          
at Newtonsoft.Json.Linq.JArray.get_Item(Object key)
at Neo4jClient.Serialization.CommonDeserializerMethods.Map(DeserializationContext context, Object targetObject, JToken parentJsonToken, IEnumerable`1 typeMappings, Int32 nestingLevel)
at Neo4jClient.Serialization.CommonDeserializerMethods.CreateAndMap(DeserializationContext context, Type type, JToken element, IEnumerable`1 typeMappings, Int32 nestingLevel)
at Neo4jClient.Serialization.CommonDeserializerMethods.MutateObject(DeserializationContext context, JToken value, IEnumerable`1 typeMappings, Int32 nestingLevel, TypeMapping mapping, Type propertyType)
at Neo4jClient.Serialization.CommonDeserializerMethods.CoerceValue(DeserializationContext context, PropertyInfo propertyInfo, JToken value, IEnumerable`1 typeMappings, Int32 nestingLevel)
at Neo4jClient.Serialization.CypherJsonDeserializer`1.<>c__DisplayClass22_0.<ReadProjectionRowUsingCtor>b__0(JToken cell, Int32 cellIndex)
at System.Linq.Enumerable.SelectIterator[TSource,TResult](IEnumerable`1 source, Func`3 selector)+MoveNext()                              
at System.Collections.Generic.LargeArrayBuilder`1.AddRange(IEnumerable`1 items)                                                          
at System.Collections.Generic.EnumerableHelpers.ToArray[T](IEnumerable`1 source)                                                         
at System.Linq.Enumerable.ToArray[TSource](IEnumerable`1 source)
at Neo4jClient.Serialization.CypherJsonDeserializer`1.ReadProjectionRowUsingCtor(DeserializationContext context, JToken row, IDictionary`2 propertiesDictionary, IList`1 columnNames, IEnumerable`1 jsonTypeMappings, ConstructorInfo ctor)
at Neo4jClient.Serialization.CypherJsonDeserializer`1.<>c__DisplayClass21_1.<ParseInProjectionMode>b__5(JToken token)                    
at System.Linq.Enumerable.SelectEnumerableIterator`2.ToArray()
at System.Linq.Enumerable.ToArray[TSource](IEnumerable`1 source)
at Neo4jClient.Serialization.CypherJsonDeserializer`1.Deserialize(String content)                                                        
--- End of inner exception stack trace ---

董事会类：

public class Board
{
[JsonProperty("id")]
public string Id { get; set; }
[JsonProperty("name")]
public string Name { get; set; }
[JsonProperty("description")]
public string Description { get; set; }
}

组类：

public class Groups
{
[JsonProperty("group")]
public Group Group { get; set; }
[JsonProperty("boards")]
public IEnumerable<Board> Boards { get; set; }
}

编辑：我也尝试挤压三元条件：Groups = groups == null ? null : groups.CollectAs<Groups>()，但这抛出了一个NotSupportedException，说"不支持FullConditionalExpression">

Answer 1

啊，我解决了。解决方案最终非常明显！Return.As<Groups>需要Return.As<IEnumerable<Groups>>