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Filter Aggregation Usage
editFilter Aggregation Usage
editDefines 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 example
edita => a .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 example
editnew 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.
{ "bethels_projects": { "filter": { "term": { "leadDeveloper.firstName": { "value": "pierce" } } }, "aggs": { "project_tags": { "terms": { "field": "curatedTags.name.keyword" } } } } }
Handling Responses
editThe AggregateDictionary found on `.Aggregations
on ISearchResponse<T>
has several helper methods
so we can fetch our aggregation results easily in the correct type.
Be sure to read more about these helper methods
response.ShouldBeValid(); var filterAgg = response.Aggregations.Filter("bethels_projects"); filterAgg.Should().NotBeNull(); filterAgg.DocCount.Should().BeGreaterThan(0); var tags = filterAgg.Terms("project_tags"); tags.Should().NotBeNull(); tags.Buckets.Should().NotBeEmpty();
Empty Filter
editWhen the collection of filters is empty or all are conditionless, NEST will serialize them to an empty object.
Fluent DSL example
edita => a .Filter("empty_filter", date => date .Filter(f => f .Bool(b => b .Filter(new QueryContainer[0]) ) ) )
Object Initializer syntax example
editnew FilterAggregation("empty_filter") { Filter = new BoolQuery { Filter = new List<QueryContainer>() } }
Example json output.
{ "empty_filter": { "filter": {} } }
Handling Responses
editresponse.ShouldNotBeValid()