Open SearchRequest.Body for read-only access

This commit opens access to the SearchRequest body generated by the DSL.

Fix #548

client.go

@@ -26,7 +26,7 @@ import (
 
 const (
 	// Version is the current version of Elastic.
-	Version = "5.0.50"
+	Version = "5.0.51"
 
 	// DefaultURL is the default endpoint of Elasticsearch on the local machine.
 	// It is used e.g. when initializing a new Client without a specific URL.

msearch.go

@@ -68,7 +68,7 @@ func (s *MultiSearchService) Do(ctx context.Context) (*MultiSearchResult, error)
 		if err != nil {
 			return nil, err
 		}
-		body, err := json.Marshal(sr.body())
+		body, err := json.Marshal(sr.Body())
 		if err != nil {
 			return nil, err
 		}

search_request.go

@@ -194,9 +194,12 @@ func (r *SearchRequest) header() interface{} {
 	return h
 }
 
-// body is used by MultiSearch to get information about the search body
+// Body allows to access the search body of the request, as generated by the DSL.
+// Notice that Body is read-only. You must not change the request body.
+//
+// Body is used e.g. by MultiSearch to get information about the search body
 // of one SearchRequest.
-// See https://www.elastic.co/guide/en/elasticsearch/reference/5.2/search-multi-search.html
-func (r *SearchRequest) body() interface{} {
+// See https://www.elastic.co/guide/en/elasticsearch/reference/5.6/search-multi-search.html
+func (r *SearchRequest) Body() interface{} {
 	return r.source
 }