有没有办法让NEST直接反序列化成结果？

Question

我目前正在考虑编写一个ElasticSearch.Net/NEST客户端作为PlainElastic.Net的可能替代品(因为ElasticSearch.Net具有我想要使用的故障转移功能)

在PlainElastic我可以这样写:

var command = new SearchCommand(index, type);
var result = Connection.Post(command, query);
var searchResult = Serializer.ToSearchResult<T>(result);
return searchResult.Documents;

这将返回一个IEnumerable,其中每个结果都是T类型.我想在NEST中使用类似的东西,并且我作为初始测试开始的是:

var result = client.Search<T>("index", "type", query, null);

但我似乎无法像PlainElastic.Net使用ToSearchResult方法那样找到反序列化结果的方法.Elasticsearch.Net/NEST提供这样的方式吗？

2015年8月8日:道歉措辞严厉的问题.我最初尝试使用NEST的是无类型版本:

var result = client.Search("index", "type", query, null);

这会带回一个我试图单独反序列化的结果,因为原始尝试使用的是打字版本:

var result = client.Search<T>("index", "type", query, null);

抛出异常:

System.NullReferenceException was unhandled by user code
  HResult=-2147467261
  Message=Object reference not set to an instance of an object.
  Source=Elasticsearch.Net
  StackTrace:
       at     Elasticsearch.Net.Serialization.PocoJsonSerializerStrategy.DeserializeObject(    Object value, Type type) in C:\code\elasticsearch-    net\src\Elasticsearch.Net\Serialization\SimpleJson.cs:line 1370
       at Elasticsearch.Net.Serialization.SimpleJson.DeserializeObject(String json, Type type, IJsonSerializerStrategy jsonSerializerStrategy) in C:\code\elasticsearch-net\src\Elasticsearch.Net\Serialization\SimpleJson.cs:line 553
   at Elasticsearch.Net.Serialization.SimpleJson.DeserializeObject[T](String json) in C:\code\elasticsearch-net\src\Elasticsearch.Net\Serialization\SimpleJson.cs:line 570
   at Elasticsearch.Net.Serialization.ElasticsearchDefaultSerializer.Deserialize[T](Stream stream) in C:\code\elasticsearch-net\src\Elasticsearch.Net\Serialization\ElasticsearchDefaultSerializer.cs:line 27
   at Elasticsearch.Net.Connection.RequestHandlers.RequestHandler.StreamToTypedResponse[T](ElasticsearchResponse`1 streamResponse, ITransportRequestState requestState, Byte[] readBytes) in C:\code\elasticsearch-net\src\Elasticsearch.Net\Connection\RequestHandlers\RequestHandler.cs:line 254
   at Elasticsearch.Net.Connection.RequestHandlers.RequestHandler.ReturnTypedResponse[T](TransportRequestState`1 requestState, ElasticsearchResponse`1 streamResponse, ElasticsearchServerError& error) in C:\code\elasticsearch-net\src\Elasticsearch.Net\Connection\RequestHandlers\RequestHandler.cs:line 106
   at Elasticsearch.Net.Connection.RequestHandlers.RequestHandler.CoordinateRequest[T](TransportRequestState`1 requestState, Int32 maxRetries, Int32 retried, Boolean& aliveResponse) in C:\code\elasticsearch-net\src\Elasticsearch.Net\Connection\RequestHandlers\RequestHandler.cs:line 131
   at Elasticsearch.Net.Connection.RequestHandlers.RequestHandler.DoRequest[T](TransportRequestState`1 requestState) in C:\code\elasticsearch-net\src\Elasticsearch.Net\Connection\RequestHandlers\RequestHandler.cs:line 177
   at Elasticsearch.Net.Connection.RequestHandlers.RequestHandler.Request[T](TransportRequestState`1 requestState, Object data) in C:\code\elasticsearch-net\src\Elasticsearch.Net\Connection\RequestHandlers\RequestHandler.cs:line 34
   at Elasticsearch.Net.Connection.Transport.DoRequest[T](String method, String path, Object data, IRequestParameters requestParameters) in C:\code\elasticsearch-net\src\Elasticsearch.Net\Connection\Transport.cs:line 343
   at Elasticsearch.Net.ElasticsearchClient.DoRequest[T](String method, String path, Object data, IRequestParameters requestParameters) in C:\code\elasticsearch-net\src\Elasticsearch.Net\ElasticsearchClient.cs:line 65
   at Elasticsearch.Net.ElasticsearchClient.Search[T](String index, String type, Object body, Func`2 requestParameters) in C:\code\elasticsearch-net\src\Elasticsearch.Net\ElasticsearchClient.Generated.cs:line 33515

因此,我认为我的原始问题仍然相同,但更多的是尝试理解为什么NEST确实在非类型化版本中检索结果但未能在类型版本中进行序列化.

Answer 1

该SearchResponse<T>有一个点击属性(类型IEnumberable<IHit<T>>,如果我没记错的话).

然后每个匹配具有Source属性,其类型为T.

所以

var enumerable = results.Hits.Select(h => h.Source);

给你你的IEnumerable<T>.