ElasticSearch NEST - all fields are NULL

Question

I'm trying to retrieve data from elastic search with NEST. Everything would be good, but NEST all fields return null. However, in debug mode I see that it counts the documents correctly but not showing the value of fields.

What I already did:

checked mapping and its seems fine to me
tried string query
tried to get source and then read data
tried NEST returns null instead of fields those solution did not help either
Renamed Product.cs field names to camelCase did not help either

Here's my code right now

public class ElasticSearch
{
    private ElasticClient _client;

    public ElasticSearch()
    {
        var node = new Uri("http://localhost:9200");
        var settings = new ConnectionSettings(node);
        settings.DefaultIndex("logsystem.logs");
        _client = new ElasticClient(settings);
    }

    public void searchResults()
    {
        var searchResults = _client.Search<Product>(s => s.AllIndices());


    }
}

Product.cs

    [BsonIgnoreExtraElements]
    public class Product
    {
        [BsonId]
        [BsonIgnore]
        public ObjectId Id { get; set; }
        [Required]
        public string Name { get; set; }
        [Required]
        public string ProductLicenseKey { get; set; }
        [Required]
        public string Action { get; set; }
        [Required]
        public string ActionName { get; set; }
        [Required]
        public string MachineId { get; set; }
    }

Mapping in ElasticSearch:

{
"logsystem.logs": {
    "mappings": {
        "properties": {
            "Action": {
                "type": "text",
                "fields": {
                    "keyword": {
                        "type": "keyword",
                        "ignore_above": 256
                    }
                }
            },
            "ActionName": {
                "type": "text",
                "fields": {
                    "keyword": {
                        "type": "keyword",
                        "ignore_above": 256
                    }
                }
            },
            "MachineId": {
                "type": "text",
                "fields": {
                    "keyword": {
                        "type": "keyword",
                        "ignore_above": 256
                    }
                }
            },
            "Name": {
                "type": "text",
                "fields": {
                    "keyword": {
                        "type": "keyword",
                        "ignore_above": 256
                    }
                }
            },
            "ProductLicenseKey": {
                "type": "text",
                "fields": {
                    "keyword": {
                        "type": "keyword",
                        "ignore_above": 256
                    }
                }
            }
        }
    }
}
}

Maybe my mapping is not right? any answer would help. Thanks.

EDIT ElasticSearch Documents get via postman:

{
"took": 11,
"timed_out": false,
"_shards": {
    "total": 1,
    "successful": 1,
    "skipped": 0,
    "failed": 0
},
"hits": {
    "total": {
        "value": 6,
        "relation": "eq"
    },
    "max_score": 1.0,
    "hits": [
        {
            "_index": "logsystem.logs",
            "_type": "_doc",
            "_id": "5e5c1ca2aaa6f1245cc38895",
            "_score": 1.0,
            "_source": {
                "Action": "Button",
                "ActionName": "Fixed Single Generation",
                "MachineId": "987-654-321",
                "Name": "System",
                "ProductLicenseKey": "123-456-789"
            }
        },
        {
            "_index": "logsystem.logs",
            "_type": "_doc",
            "_id": "5e5c1cb0aaa6f1245cc38896",
            "_score": 1.0,
            "_source": {
                "Action": "Button",
                "ActionName": "Fixed Multiple Generation",
                "MachineId": "987-654-321",
                "Name": "System",
                "ProductLicenseKey": "123-456-789"
            }
        },
        {
            "_index": "logsystem.logs",
            "_type": "_doc",
            "_id": "5e5c1cbdaaa6f1245cc38897",
            "_score": 1.0,
            "_source": {
                "Action": "Button",
                "ActionName": "Trackers Single Generation",
                "MachineId": "987-654-321",
                "Name": "System",
                "ProductLicenseKey": "123-456-789"
            }
        },
        {
            "_index": "logsystem.logs",
            "_type": "_doc",
            "_id": "5e5c1ccbaaa6f1245cc38898",
            "_score": 1.0,
            "_source": {
                "Action": "Button",
                "ActionName": "Trackers Multiple Generation",
                "MachineId": "987-654-321",
                "Name": "System",
                "ProductLicenseKey": "123-456-789"
            }
        },
        {
            "_index": "logsystem.logs",
            "_type": "_doc",
            "_id": "5e5c1cd3aaa6f1245cc38899",
            "_score": 1.0,
            "_source": {
                "Action": "Button",
                "ActionName": "Fixed Multiple Generation",
                "MachineId": "987-654-321",
                "Name": "System",
                "ProductLicenseKey": "123-456-789"
            }
        },
        {
            "_index": "logsystem.logs",
            "_type": "_doc",
            "_id": "5e5c1ce0aaa6f1245cc3889a",
            "_score": 1.0,
            "_source": {
                "Action": "Button",
                "ActionName": "Tree Generation",
                "MachineId": "987-654-321",
                "Name": "System",
                "ProductLicenseKey": "123-456-789"
            }
        }
    ]
 }
}

Could you post how the records looks like in the elastic search ? — Viresh Mathad

Julius Julius · Accepted Answer · 2020-03-03T07:50:51

So the problem was that client tried to deserialize camelCased JSON objects keys to the POCO properties and is strict for casting.

Solution: When creating ES client add settings property DefaultFieldNameInferrer on ConnectionSettings.

    public ElasticSearch()
    {
        var node = new Uri("http://localhost:9200");
        var settings = new ConnectionSettings(node);
        settings.DefaultIndex("logsystem.logs");
        settings.DefaultFieldNameInferrer(p => p);
        _client = new ElasticClient(settings);
    }

ElasticSearch NEST - all fields are NULL

1 Answers