Fix overwrite preloading associations, close #4134

callbacks/query.go

@@ -172,9 +172,11 @@ func Preload(db *gorm.DB) {
 			if name == clause.Associations {
 				for _, rel := range db.Statement.Schema.Relationships.Relations {
 					if rel.Schema == db.Statement.Schema {
+						if _, ok := preloadMap[rel.Name]; !ok {
 							preloadMap[rel.Name] = map[string][]interface{}{}
 						}
 					}
+				}
 			} else {
 				preloadFields := strings.Split(name, ".")
 				if _, ok := preloadMap[preloadFields[0]]; !ok {