Filter Aggregation Usageedit

Defines a single bucket of all the documents in the current document set context that match a specified filter. Often this will be used to narrow down the current aggregation context to a specific set of documents.

Be sure to read the Elasticsearch documentation on Filter Aggregation

Fluent DSL exampleedit

s => s
.Aggregations(aggs => aggs
    .Filter("bethels_projects", date => date
        .Filter(q => q.Term(p => p.LeadDeveloper.FirstName, FirstNameToFind))
        .Aggregations(childAggs => childAggs
            .Terms("project_tags", avg => avg.Field(p => p.CuratedTags.First().Name.Suffix("keyword")))
        )
    )
)

Object Initializer syntax exampleedit

new SearchRequest<Project>
{
    Aggregations = new FilterAggregation("bethels_projects")
    {
        Filter = new TermQuery {Field = Field<Project>(p => p.LeadDeveloper.FirstName), Value = FirstNameToFind},
        Aggregations =
            new TermsAggregation("project_tags") { Field = Field<Project>(p => p.CuratedTags.First().Name.Suffix("keyword")) }
    }
}

Example json output. 

{
  "aggs": {
    "bethels_projects": {
      "filter": {
        "term": {
          "leadDeveloper.firstName": {
            "value": "pierce"
          }
        }
      },
      "aggs": {
        "project_tags": {
          "terms": {
            "field": "curatedTags.name.keyword"
          }
        }
      }
    }
  }
}