How to write the equivalent query in NEST,C# for the date_histogram by week

Question

I need to convert the following query into c# in using NEST.

"aggs": {
          "number_of_weeks": {
              "date_histogram": {
                    "field": "@timestamp",
                    "interval": "week"
                  }
                }
     }

in Kibana the output is

I wrote the following query but it give me zero bucket while in Kibana it return many result in buckets

var query3 = EsClient.Search<doc>(q => q
                      .Index("SomeIndex")
                      .Size(0)
                      .Aggregations(agg => agg.DateHistogram("group_by_week", e => e.Field(p => p.timestamp) .Interval(DateInterval.Week)
                  )) ;
var resultquery3 = query3.Aggregations.DateHistogram("group_by_week");

in vs studio the output is

Answer 1

The problem is likely that

e => e.Field(p => p.timestamp)

does not serialize to the "@timestamp" field in Elasticsearch. For this to work, you would need to either map it with an attribute on the POCO

public class Doc
{
    [Date(Name = "@timestamp")]
    public DateTime timestamp { get; set; }
}

or map it on ConnectionSettings

var pool = new SingleNodeConnectionPool(new Uri("http://localhost:9200"));
var settings = new ConnectionSettings(pool)
    .DefaultMappingFor<Doc>(m => m
        .PropertyName(e => e.timestamp, "@timestamp")
    );

var client = new ElasticClient(settings);

Alternatively, you can simply pass a string to .Field(), which implicitly converts

.Field("@timestamp")