From 282f11af1900a36646b607797273056d76350223 Mon Sep 17 00:00:00 2001
From: gstvg <28798827+gstvg@users.noreply.github.com>
Date: Sun, 9 Sep 2018 19:52:32 -0300
Subject: [PATCH] Support only preloading  (#1926)

* add support for only preloading relations on an already populated model

* Update callback_query.go

comments
---
 callback_query.go | 5 +++++
 main.go           | 5 +++++
 2 files changed, 10 insertions(+)

diff --git a/callback_query.go b/callback_query.go
index ba10cc7d..593e5d30 100644
--- a/callback_query.go
+++ b/callback_query.go
@@ -18,6 +18,11 @@ func queryCallback(scope *Scope) {
 	if _, skip := scope.InstanceGet("gorm:skip_query_callback"); skip {
 		return
 	}
+	
+	//we are only preloading relations, dont touch base model
+	if _, skip := scope.InstanceGet("gorm:only_preload"); skip {
+		return
+	}
 
 	defer scope.trace(NowFunc())
 
diff --git a/main.go b/main.go
index 364d8e8e..4dbda61e 100644
--- a/main.go
+++ b/main.go
@@ -314,6 +314,11 @@ func (s *DB) Find(out interface{}, where ...interface{}) *DB {
 	return s.NewScope(out).inlineCondition(where...).callCallbacks(s.parent.callbacks.queries).db
 }
 
+//Preloads preloads relations, don`t touch out
+func (s *DB) Preloads(out interface{}) *DB {
+	return s.NewScope(out).InstanceSet("gorm:only_preload", 1).callCallbacks(s.parent.callbacks.queries).db
+}
+
 // Scan scan value to a struct
 func (s *DB) Scan(dest interface{}) *DB {
 	return s.NewScope(s.Value).Set("gorm:query_destination", dest).callCallbacks(s.parent.callbacks.queries).db