Add offset option to histogram aggregation

CHANGELOG-3.0.md

@@ -332,6 +332,10 @@ The combination of `Metric(string)` and `Metrics(...string)` has been replaced b
 
 Services generally return a typed response from a `Do` func. Those structs are exported so that they can be passed around in your own application. In Elastic 3.0 however, we changed that (most) sub-structs are now unexported, meaning: You can only pass around the whole response, not sub-structures of it. This makes it easier for restructuring responses according to the Elasticsearch API. See [`ClusterStateResponse`](https://github.com/olivere/elastic/blob/release-branch.v3/cluster_state.go#L182) as an example.
 
+## Add offset to Histogram aggregation
+
+Histogram aggregations now have an [offset](https://github.com/elastic/elasticsearch/pull/9505) option.
+
 ## Services
 
 ### REST API specification

search_aggs_bucket_histogram.go

@@ -21,6 +21,7 @@ type HistogramAggregation struct {
 	minDocCount       *int64
 	extendedBoundsMin *int64
 	extendedBoundsMax *int64
+	offset            *int64
 }
 
 func NewHistogramAggregation() *HistogramAggregation {
@@ -141,6 +142,12 @@ func (a *HistogramAggregation) MinDocCount(minDocCount int64) *HistogramAggregat
 	return a
 }
 
+func (a *HistogramAggregation) ExtendedBounds(min, max int64) *HistogramAggregation {
+	a.extendedBoundsMin = &min
+	a.extendedBoundsMax = &max
+	return a
+}
+
 func (a *HistogramAggregation) ExtendedBoundsMin(min int64) *HistogramAggregation {
 	a.extendedBoundsMin = &min
 	return a
@@ -151,6 +158,11 @@ func (a *HistogramAggregation) ExtendedBoundsMax(max int64) *HistogramAggregatio
 	return a
 }
 
+func (a *HistogramAggregation) Offset(offset int64) *HistogramAggregation {
+	a.offset = &offset
+	return a
+}
+
 func (a *HistogramAggregation) Source() (interface{}, error) {
 	// Example:
 	// {
@@ -192,6 +204,9 @@ func (a *HistogramAggregation) Source() (interface{}, error) {
 		}
 		opts["order"] = o
 	}
+	if a.offset != nil {
+		opts["offset"] = *a.offset
+	}
 	if a.minDocCount != nil {
 		opts["min_doc_count"] = *a.minDocCount
 	}

search_aggs_bucket_histogram_test.go

@@ -27,7 +27,7 @@ func TestHistogramAggregation(t *testing.T) {
 }
 
 func TestHistogramAggregationWithMetaData(t *testing.T) {
-	agg := NewHistogramAggregation().Field("price").Interval(50).Meta(map[string]interface{}{"name": "Oliver"})
+	agg := NewHistogramAggregation().Field("price").Offset(10).Interval(50).Meta(map[string]interface{}{"name": "Oliver"})
 	src, err := agg.Source()
 	if err != nil {
 		t.Fatal(err)
@@ -37,7 +37,7 @@ func TestHistogramAggregationWithMetaData(t *testing.T) {
 		t.Fatalf("marshaling to JSON failed: %v", err)
 	}
 	got := string(data)
-	expected := `{"histogram":{"field":"price","interval":50},"meta":{"name":"Oliver"}}`
+	expected := `{"histogram":{"field":"price","interval":50,"offset":10},"meta":{"name":"Oliver"}}`
 	if got != expected {
 		t.Errorf("expected\n%s\n,got:\n%s", expected, got)
 	}