feat: add support for search after

search.go

@@ -15,16 +15,17 @@ import (
 // Not all features of the search API are currently supported, but a request can
 // currently include a query, aggregations, and more.
 type SearchRequest struct {
-	aggs       []Aggregation
-	explain    *bool
-	from       *uint64
-	highlight  Mappable
-	postFilter Mappable
-	query      Mappable
-	size       *uint64
-	sort       Sort
-	source     Source
-	timeout    *time.Duration
+	aggs        []Aggregation
+	explain     *bool
+	from        *uint64
+	highlight   Mappable
+	searchAfter []string
+	postFilter  Mappable
+	query       Mappable
+	size        *uint64
+	sort        Sort
+	source      Source
+	timeout     *time.Duration
 }
 
 // Search creates a new SearchRequest object, to be filled via method chaining.
@@ -74,6 +75,12 @@ func (req *SearchRequest) Sort(name string, order Order) *SearchRequest {
 	return req
 }
 
+// SearchAfter retrieve the sorted result
+func (req *SearchRequest) SearchAfter(s ...string) *SearchRequest {
+	req.searchAfter = append(req.searchAfter, s...)
+	return req
+}
+
 // Explain sets whether the ElasticSearch API should return an explanation for
 // how each hit's score was calculated.
 func (req *SearchRequest) Explain(b bool) *SearchRequest {
@@ -105,7 +112,6 @@ func (req *SearchRequest) Highlight(highlight Mappable) *SearchRequest {
 	return req
 }
 
-
 // Map implements the Mappable interface. It converts the request to into a
 // nested map[string]interface{}, as expected by the go-elasticsearch library.
 func (req *SearchRequest) Map() map[string]interface{} {
@@ -142,6 +148,9 @@ func (req *SearchRequest) Map() map[string]interface{} {
 	if req.highlight != nil {
 		m["highlight"] = req.highlight.Map()
 	}
+	if req.searchAfter != nil {
+		m["search_after"] = req.searchAfter
+	}
 
 	source := req.source.Map()
 	if len(source) > 0 {