"DataMember" attribute is not applied when deserializing searching query

[QuanTran91]

NEST/Elasticsearch.Net version: 6.0.1

Elasticsearch version: 6.0.1

Description of the problem including expected versus actual behavior:

I have a document model as below:

[DataContract(Name = "source_entity")]
public class SourceEntity
{
    [DataMember(Name = "name")]
    public string Name { get; set; }
    
    [DataMember(Name = "display_name")]
    public string DisplayName { get; set; }
}

And here is the code for inserting random source entities:

public class AddEntitySample
{
    private ElasticClient elasticClient;

    public AddEntitySample()
    {
        var node = new Uri("http://localhost:9200");
        var pool = new SingleNodeConnectionPool(new Uri("http://localhost:9200"));
        var settings = new ConnectionSettings(pool);
        
        settings.DefaultMappingFor<SourceEntity>(t => t.IndexName("source_entity_fun"));
        settings.DisableDirectStreaming();
        settings.OnRequestCompleted((t) =>
        {
            var a = t.DebugInformation;
        });
        elasticClient = new ElasticClient(settings);
    }

    public void AddSampleData()
    {
        elasticClient.DeleteIndex(Indices.Index<SourceEntity>());
        var enumberation = Enumerable.Range(0, 1000).Select(index => new SourceEntity
        {
            Name = "Name " + index,
            DisplayName = "DisplayName" + index
        });        
        var response = elasticClient.BulkAsync(t => t.IndexMany(enumberation), 
            new System.Threading.CancellationToken()).Result;
    }        
}

After insert some items in elastic db, I use this command "GET source_entity_fun/_mapping" (in Kibana dev console) to get the schemas of SourceEntity in elastic db.
And here is the json format of the document

{
  "source_entity_test": {
    "mappings": {
      "sourceentity": {
        "properties": {
          "display_name": {
            "type": "text",
            "fields": {
              "keyword": {
                "type": "keyword",
                "ignore_above": 256
              }
            }
          },
          "name": {
            "type": "text",
            "fields": {
              "keyword": {
                "type": "keyword",
                "ignore_above": 256
              }
            }
          }
        }
      }
    }
  }
}

When I make a simple query:

var query = elasticClient.Search<SourceEntity>(t => t.Query(u => u.Terms(k => k.Field(h => h.DisplayName).Terms("23"))));

And here is the json query generated (using DebugInformation):

{"query":{"terms":{"displayName":["23"]}}}

As the result, there are no documents returned.
I would expected is should be :

{"query":{"terms":{"display_name":["23"]}}}

(with underscore)

I tried to use NEST.JsonNetSerializer but it did not work.
Could you help me, please?
Thanks.

[russcam]

Hey @QuanTran91, if you use

[ElasticsearchType(Name = "source_entity")]
public class SourceEntity
{
    [PropertyName("name")]
    public string Name { get; set; }

    [PropertyName("display_name")]
    public string DisplayName { get; set; }
}

It will work as expected.

[QuanTran91]

Hi @russcam
Actually, I have several ways to fix it. But what I'm mentioning here is the inconsistent implementation in entity serializing in Nest. Hope you guys think about it.

[russcam]

inconsistent implementation in entity serializing in Nest

What is serialization inconsistent with?

NEST has never supported DataContract and DataMember attributes as far as I can see; it has always had its own attributes to support entity and property naming.

One of the reasons for not using DataContract and DataMember attributes is that it creates a dependency on System.Runtime.Serialization, a dependency that is required only to support these attributes, and this would be forced on all NEST consumers. There are abstractions within the client for a consumer to add support for these attributes, or any other attributes, if they need to.

[QuanTran91]

If Nest does not support DataContract and DataMember, why does the property name of "DisplayName" is "display_name" not "displayName" in json format document as I expected. That's confusing me.

[russcam]

By default, NEST camel cases property names. This behaviour can be changed with .DefaultFieldNameInferrer(Func<string,string>) on ConnectionSettings.

[QuanTran91]

Hi @russcam , when I removed DataContract and DataMember from entity, the property names are showed in camel cases format as default (correct behavior). However, when I put DataContract and DataMember into it (with snake case style), it somehow affects to json format of document ("displayName" now turn to "display_name"). That is the issue I concern about.

[russcam]

Can you provide a reproducible example?

[QuanTran91]

I have already post at first, you can take a look at it:

{
  "source_entity_test": {
    "mappings": {
      "sourceentity": {
        "properties": {
          "`**display_name**`": {
            "type": "text",
            "fields": {
              "keyword": {
                "type": "keyword",
                "ignore_above": 256
              }
            }
          },
          "name": {
            "type": "text",
            "fields": {
              "keyword": {
                "type": "keyword",
                "ignore_above": 256
              }
            }
          }
        }
      }
    }
  }
}

[russcam]

Could you please provide a reproducible example that demonstrates how the mapping you have posted is generated from the DataMember attributed type

[QuanTran91]

Hi @russcam , I have updated my top post. Could you take a look at it? Thanks.

[russcam]

Thank you for the reproducible example @QuanTran91, this is a bug.