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Filters Aggregation Usage

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Filters Aggregation Usage

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Defines a multi bucket aggregations where each bucket is associated with a filter. Each bucket will collect all documents that match its associated filter. For documents that do not match any filter, these will be collected in the other bucket.

Be sure to read the Elasticsearch documentation Filters Aggregation

Named filters

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Fluent DSL example

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a => a
.Filters("projects_by_state", agg => agg
    .OtherBucket()
    .OtherBucketKey("other_states_of_being")
    .NamedFilters(filters => filters
        .Filter("belly_up", f => f.Term(p => p.State, StateOfBeing.BellyUp))
        .Filter("stable", f => f.Term(p => p.State, StateOfBeing.Stable))
        .Filter("very_active", f => f.Term(p => p.State, StateOfBeing.VeryActive))
    )
    .Aggregations(childAggs => childAggs
        .Terms("project_tags", avg => avg.Field(p => p.CuratedTags.First().Name.Suffix("keyword")))
    )
)

Object Initializer syntax example

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new FiltersAggregation("projects_by_state")
{
    OtherBucket = true,
    OtherBucketKey = "other_states_of_being",
    Filters = new NamedFiltersContainer
    {
        { "belly_up", Query<Project>.Term(p => p.State, StateOfBeing.BellyUp) },
        { "stable", Query<Project>.Term(p => p.State, StateOfBeing.Stable) },
        { "very_active", Query<Project>.Term(p => p.State, StateOfBeing.VeryActive) }
    },
    Aggregations =
        new TermsAggregation("project_tags") { Field = Field<Project>(p => p.CuratedTags.First().Name.Suffix("keyword")) }
}

Example json output.

{
  "projects_by_state": {
    "filters": {
      "other_bucket": true,
      "other_bucket_key": "other_states_of_being",
      "filters": {
        "belly_up": {
          "term": {
            "state": {
              "value": "BellyUp"
            }
          }
        },
        "stable": {
          "term": {
            "state": {
              "value": "Stable"
            }
          }
        },
        "very_active": {
          "term": {
            "state": {
              "value": "VeryActive"
            }
          }
        }
      }
    },
    "aggs": {
      "project_tags": {
        "terms": {
          "field": "curatedTags.name.keyword"
        }
      }
    }
  }
}

Handling Responses

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The AggregateDictionary found on `.Aggregations on SearchResponse<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.Filters("projects_by_state");
filterAgg.Should().NotBeNull();

var namedResult = filterAgg.NamedBucket("belly_up");
namedResult.Should().NotBeNull();
namedResult.DocCount.Should().BeGreaterThan(0);

namedResult = filterAgg.NamedBucket("stable");
namedResult.Should().NotBeNull();
namedResult.DocCount.Should().BeGreaterThan(0);

namedResult = filterAgg.NamedBucket("very_active");
namedResult.Should().NotBeNull();
namedResult.DocCount.Should().BeGreaterThan(0);

namedResult = filterAgg.NamedBucket("other_states_of_being");
namedResult.Should().NotBeNull();
namedResult.DocCount.Should().Be(0);

Anonymous filters

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Fluent DSL example

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a => a
.Filters("projects_by_state", agg => agg
    .OtherBucket()
    .AnonymousFilters(
        f => f.Term(p => p.State, StateOfBeing.BellyUp),
        f => f.Term(p => p.State, StateOfBeing.Stable),
        f => f.Term(p => p.State, StateOfBeing.VeryActive)
    )
    .Aggregations(childAggs => childAggs
        .Terms("project_tags", avg => avg.Field(p => p.CuratedTags.First().Name.Suffix("keyword")))
    )
)

Object Initializer syntax example

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new FiltersAggregation("projects_by_state")
{
    OtherBucket = true,
    Filters = new List<QueryContainer>
    {
        Query<Project>.Term(p => p.State, StateOfBeing.BellyUp),
        Query<Project>.Term(p => p.State, StateOfBeing.Stable),
        Query<Project>.Term(p => p.State, StateOfBeing.VeryActive)
    },
    Aggregations =
        new TermsAggregation("project_tags") { Field = Field<Project>(p => p.CuratedTags.First().Name.Suffix("keyword")) }
}

Example json output.

{
  "projects_by_state": {
    "filters": {
      "other_bucket": true,
      "filters": [
        {
          "term": {
            "state": {
              "value": "BellyUp"
            }
          }
        },
        {
          "term": {
            "state": {
              "value": "Stable"
            }
          }
        },
        {
          "term": {
            "state": {
              "value": "VeryActive"
            }
          }
        }
      ]
    },
    "aggs": {
      "project_tags": {
        "terms": {
          "field": "curatedTags.name.keyword"
        }
      }
    }
  }
}

Handling Responses

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response.ShouldBeValid();

var filterAgg = response.Aggregations.Filters("projects_by_state");
filterAgg.Should().NotBeNull();
var results = filterAgg.AnonymousBuckets();
results.Count.Should().Be(4);

foreach (var singleBucket in results.Take(3)) singleBucket.DocCount.Should().BeGreaterThan(0);

results.Last().DocCount.Should().Be(0);

The last bucket is the other bucket

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