Support for structs in document fields

goes.go

@@ -13,6 +13,7 @@ import (
 	"io/ioutil"
 	"net/http"
 	"net/url"
+	"reflect"
 	"strconv"
 	"strings"
 )
@@ -139,13 +140,25 @@ func (c *Connection) BulkSend(documents []Document) (Response, error) {
 		bulkData[i] = action
 		i++
 
-		if len(doc.Fields) > 0 {
-			fields := make(map[string]interface{}, len(doc.Fields))
-			for fieldName, fieldValue := range doc.Fields {
-				fields[fieldName] = fieldValue
+		if doc.Fields != nil {
+			if docFields, ok := doc.Fields.(map[string]interface{}); ok {
+				if len(docFields) == 0 {
+					continue
+				}
+			} else {
+				typeOfFields := reflect.TypeOf(doc.Fields)
+				if typeOfFields.Kind() == reflect.Ptr {
+					typeOfFields = typeOfFields.Elem()
+				}
+				if typeOfFields.Kind() != reflect.Struct {
+					return Response{}, fmt.Errorf("Document fields not in struct or map[string]interface{} format")
+				}
+				if typeOfFields.NumField() == 0 {
+					continue
+				}
 			}
 
-			sources, err := json.Marshal(fields)
+			sources, err := json.Marshal(doc.Fields)
 			if err != nil {
 				return Response{}, err
 			}

structs.go

@@ -102,7 +102,7 @@ type Document struct {
 	Type        string
 	Id          interface{}
 	BulkCommand string
-	Fields      map[string]interface{}
+	Fields      interface{}
 }
 
 // Represents the "items" field in a _bulk response