ElasticSearch Result using NEST

Elastic Stack Elasticsearch
1

Hi all. I'm using NEST for ES in .net

 string wordInfoQuery = @"{
                ""query"": {
                    ""match_phrase"":{
                        ""Answer"":{
                                      ""query"": ""brown dog"",
                                      ""slop"": "3"
                                    }
                                }
                            }
                        }";

           

           try
                {
       
                    if (client != null)
                    {
                        var callResult = client.LowLevel.Search<string>(wordInfoQuery);
                        Response.Write(client.LowLevel);
                        Response.Write("query=" + wordInfoQuery);
                        Response.Write(callResult.Body);
                    }
                    
                }

In the above code, when i run the code in debug mode, I'm getting a successful post message with query result(for eg. max_Score = 0.28) where as if i run the code in browser mode, it is still making a call to ES , but the result is empty(max_score =""). I dont know why is this happening.
someone please help in solving this.

thanks in advance

2

A few observations

  1. You use "Answer" as the field name for the match_phrase query in your json but NEST by default will camel case all CLR property names when mapping, indexing, searching, etc. This should be "answer" or change the default field name inference on Connection Settings
  2. When there are no results for a match_phrase query, max_score will be null so you will need to handle this case. In your example, a slop of 3 produces no hits for the query so max_score is null. If you change slop to 5, you get the document back and a value for max_score.
  3. I'd recommend using the Fluent API or the Object Initializer Syntax in NEST unless you have good reason not to (and if you do have a reason, we'd love to know!). There are usage examples of all of the Query DSL for NEST 2.x that should hopefully help :slight_smile:

An example

void Main()
{
    var pool = new SingleNodeConnectionPool(new Uri("http://localhost:9200"));
    var defaultIndex = "zzz";

    var connectionSettings = new ConnectionSettings(pool)
            .DefaultIndex(defaultIndex)
            .MapDefaultTypeNames(m => m.Add(typeof(Class1), "omg"))
            .PrettyJson()
            .DisableDirectStreaming()
            .OnRequestCompleted(response =>
                {
                        // log out the request
                        if (response.RequestBodyInBytes != null)
                    {
                        Console.WriteLine(
                            $"{response.HttpMethod} {response.Uri} \n" +
                            $"{Encoding.UTF8.GetString(response.RequestBodyInBytes)}");
                    }
                    else
                    {
                        Console.WriteLine($"{response.HttpMethod} {response.Uri}");
                    }

                        // log out the response
                        if (response.ResponseBodyInBytes != null)
                    {
                        Console.WriteLine($"Status: {response.HttpStatusCode}\n" +
                                 $"{Encoding.UTF8.GetString(response.ResponseBodyInBytes)}\n" +
                                 $"{new string('-', 30)}\n");
                    }
                    else
                    {
                        Console.WriteLine($"Status: {response.HttpStatusCode}\n" +
                                 $"{new string('-', 30)}\n");
                    }
                });

    var client = new ElasticClient(connectionSettings);

    if (client.IndexExists(defaultIndex).Exists)
    {
        client.DeleteIndex(defaultIndex);
    }

    client.CreateIndex(defaultIndex);

    client.Index(new Class1
    {
        Id = 1,
        Answer = "The quick brown fox jumps over the lazy dog"
    }, i => i.Refresh());

    var searchResponse = client.Search<Class1>(s => s
        .Query(q => q
            .MatchPhrase(mp => mp
                .Field(f => f.Answer)
                .Query("brown dog")
                .Slop(5)
            )
        )
    );

    Console.WriteLine(searchResponse.MaxScore);
}

public class Class1
{
    public int Id { get; set; }
    public string Answer { get; set; }
}

Writes out the following to the console

HEAD http://localhost:9200/zzz?pretty=true
Status: 200

------------------------------

DELETE http://localhost:9200/zzz?pretty=true
Status: 200
{
  "acknowledged" : true
}

------------------------------

PUT http://localhost:9200/zzz?pretty=true 
{}
Status: 200
{
  "acknowledged" : true
}

------------------------------

PUT http://localhost:9200/zzz/omg/1?pretty=true&refresh=true 
{
  "id": 1,
  "answer": "The quick brown fox jumps over the lazy dog"
}
Status: 201
{
  "_index" : "zzz",
  "_type" : "omg",
  "_id" : "1",
  "_version" : 1,
  "_shards" : {
	"total" : 2,
	"successful" : 1,
	"failed" : 0
  },
  "created" : true
}

------------------------------

POST http://localhost:9200/zzz/omg/_search?pretty=true 
{
  "query": {
	"match": {
	  "answer": {
		"type": "phrase",
		"query": "brown dog",
		"slop": 5
	  }
	}
  }
}
Status: 200
{
  "took" : 1,
  "timed_out" : false,
  "_shards" : {
	"total" : 5,
	"successful" : 5,
	"failed" : 0
  },
  "hits" : {
	"total" : 1,
	"max_score" : 0.07829509,
	"hits" : [ {
	  "_index" : "zzz",
	  "_type" : "omg",
	  "_id" : "1",
	  "_score" : 0.07829509,
	  "_source" : {
		"id" : 1,
		"answer" : "The quick brown fox jumps over the lazy dog"
	  }
	} ]
  }
}

------------------------------ 
0.07829509
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