Fixing GetSourceRequest (#402)

* Fixing GetSourceRequest source field

Signed-off-by: Vacha Shah <vachshah@amazon.com>

* Adding sample code for get source api

Signed-off-by: Vacha Shah <vachshah@amazon.com>

* Adding changelog

Signed-off-by: Vacha Shah <vachshah@amazon.com>

---------

Signed-off-by: Vacha Shah <vachshah@amazon.com>

CHANGELOG.md

@@ -36,6 +36,7 @@ Inspired from [Keep a Changelog](https://keepachangelog.com/en/1.0.0/)
 ### Fixed
 
 - Corrects AWSv4 signature on DataStream Stats with no index name specified ([#338](https://github.com/opensearch-project/opensearch-go/pull/338))
+- Fixed GetSourceRequest `Source` field and deprecated the `Source` parameter ([#402](https://github.com/opensearch-project/opensearch-go/pull/402))
 
 ### Security
 

guides/search.md

@@ -186,6 +186,42 @@ log.Printf("deleted pits: [%+v]", delpits)
 
 Note that a point-in-time is associated with an index or a set of index. So, when performing a search with a point-in-time, you DO NOT specify the index in the search.
 
+## Source API
+
+The source API returns the source of the documents with included or excluded fields. The following example returns all fields from document source in the `movies` index:
+
+```go
+getSourceRequest := opensearchapi.GetSourceRequest{
+    Index:      "movies",
+    DocumentID: "1",
+}
+getSourceResponse, err := getSourceRequest.Do(context.Background(), client)
+if err != nil {
+    log.Printf("error occurred: [%s]", err.Error())
+}
+log.Printf("source: [%+v]", getSourceResponse)
+```
+
+To include certain fields in the source response, use `SourceIncludes` or `Source`(this field is deprecated and `SourceIncludes` is recommended to be used instead). To get only required fields:
+
+```go
+getSourceRequest = opensearchapi.GetSourceRequest{
+    Index:      "movies",
+    DocumentID: "1",
+    SourceIncludes:     []string{"title"},
+}
+```
+
+To exclude certain fields in the source response, use `SourceExcludes` as follows:
+
+```go
+getSourceRequest = opensearchapi.GetSourceRequest{
+    Index:      "movies",
+    DocumentID: "1",
+    SourceExcludes: []string{"title"},
+}
+```
+
 ## Cleanup
 
 ```go

opensearchapi/api.get_source.go

@@ -60,7 +60,8 @@ type GetSourceRequest struct {
 	Realtime       *bool
 	Refresh        *bool
 	Routing        string
-	Source         interface{}
+	// Deprecated: This parameter is similar to SourceIncludes, please use that instead.
+	Source         []string
 	SourceExcludes []string
 	SourceIncludes []string
 	Version        *int
@@ -113,12 +114,8 @@ func (r GetSourceRequest) Do(ctx context.Context, transport Transport) (*Respons
 		params["routing"] = r.Routing
 	}
 
-	if source, ok := r.Source.(bool); ok {
-		params["_source"] = strconv.FormatBool(source)
-	} else if source, ok := r.Source.(string); ok && source != "" {
-		params["_source"] = source
-	} else if sources, ok := r.Source.([]string); ok && len(sources) > 0 {
-		params["_source"] = strings.Join(sources, ",")
+	if len(r.Source) > 0 {
+		params["_source"] = strings.Join(r.Source, ",")
 	}
 
 	if len(r.SourceExcludes) > 0 {
@@ -236,9 +233,9 @@ func (f GetSource) WithRouting(v string) func(*GetSourceRequest) {
 	}
 }
 
-// WithSource - true or false to return the _source field or not, or a list of fields to return.
+// WithSource - a list of fields to return. This field is deprecated, please use SourceIncludes instead.
 //
-func (f GetSource) WithSource(v interface{}) func(*GetSourceRequest) {
+func (f GetSource) WithSource(v ...string) func(*GetSourceRequest) {
 	return func(r *GetSourceRequest) {
 		r.Source = v
 	}

opensearchapi/opensearchapi_integration_test.go

@@ -38,6 +38,7 @@ import (
 	"strings"
 	"testing"
 	"time"
+	"github.com/stretchr/testify/assert"
 
 	"github.com/opensearch-project/opensearch-go/v2"
 	"github.com/opensearch-project/opensearch-go/v2/opensearchapi"
@@ -123,6 +124,68 @@ func TestAPI(t *testing.T) {
 			t.Fatalf("Failed to index data: %s", err)
 		}
 
+		// Add a document to the index.
+		document := strings.NewReader(`{
+			"title": "Moneyball",
+			"director": "Bennett Miller",
+			"year": "2011"
+		}`)
+
+		docId := "1"
+		req := opensearchapi.IndexRequest{
+			Index:      "test",
+			DocumentID: docId,
+			Body:       document,
+		}
+		insertResponse, err := req.Do(context.Background(), client)
+		if err != nil {
+			fmt.Println("failed to insert document ", err)
+		}
+		defer insertResponse.Body.Close()
+
+		// Get the document with source filters
+		getSourceRequest := opensearchapi.GetSourceRequest{
+			Index:      "test",
+			DocumentID: "1",
+			Source:     []string{"title"},
+		}
+		getSourceResponse, err := getSourceRequest.Do(context.Background(), client)
+		if err != nil {
+			fmt.Println("failed to get source ", err)
+		}
+		assert.Equal(t, 200, getSourceResponse.StatusCode)
+		assert.Contains(t, getSourceResponse.String(), "title")
+		assert.NotContains(t, getSourceResponse.String(), "director")
+		defer getSourceResponse.Body.Close()
+
+		getSourceRequest = opensearchapi.GetSourceRequest{
+			Index:      "test",
+			DocumentID: "1",
+			SourceIncludes:     []string{"title"},
+		}
+		getSourceResponse, err = getSourceRequest.Do(context.Background(), client)
+		if err != nil {
+			fmt.Println("failed to get source ", err)
+		}
+		assert.Equal(t, 200, getSourceResponse.StatusCode)
+		assert.Contains(t, getSourceResponse.String(), "title")
+		assert.NotContains(t, getSourceResponse.String(), "director")
+		defer getSourceResponse.Body.Close()
+
+		getSourceRequest = opensearchapi.GetSourceRequest{
+			Index:      "test",
+			DocumentID: "1",
+			SourceExcludes: []string{"title"},
+		}
+		getSourceResponse, err = getSourceRequest.Do(context.Background(), client)
+		if err != nil {
+			fmt.Println("failed to get source ", err)
+		}
+		assert.Equal(t, 200, getSourceResponse.StatusCode)
+		assert.Contains(t, getSourceResponse.String(), "director")
+		assert.NotContains(t, getSourceResponse.String(), "title")
+		defer getSourceResponse.Body.Close()
+
 		// Launch reindexing task with wait_for_completion=false
 		//
 		res, err = client.Reindex(