From f159d05209d0018e492b9273e508c22a75523331 Mon Sep 17 00:00:00 2001
From: huydx <doxuanhuy@gmail.com>
Date: Mon, 18 Jul 2016 16:43:19 +0900
Subject: [PATCH] Support count distinct

---
 main.go  | 5 +++++
 scope.go | 7 +++++++
 2 files changed, 12 insertions(+)

diff --git a/main.go b/main.go
index 04f39228..f34458c5 100644
--- a/main.go
+++ b/main.go
@@ -298,6 +298,11 @@ func (s *DB) Count(value interface{}) *DB {
 	return s.NewScope(s.Value).count(value).db
 }
 
+// CountDistinct get how many distinct records for a model
+func (s *DB) CountDistinct(value interface{}, columnName string) *DB {
+	return s.NewScope(s.Value).countDistinct(value, columnName).db
+}
+
 // Related get related associations
 func (s *DB) Related(value interface{}, foreignKeys ...string) *DB {
 	return s.clone().NewScope(s.Value).related(value, foreignKeys...).db
diff --git a/scope.go b/scope.go
index 974ff035..5c03b3bc 100644
--- a/scope.go
+++ b/scope.go
@@ -921,6 +921,13 @@ func (scope *Scope) count(value interface{}) *Scope {
 	return scope
 }
 
+func (scope *Scope) countDistinct(value interface{}, column string) *Scope {
+	scope.Search.Select(fmt.Sprintf("count(%s)", column))
+	scope.Search.countingQuery = true
+	scope.Err(scope.row().Scan(value))
+	return scope
+}
+
 func (scope *Scope) typeName() string {
 	typ := scope.IndirectValue().Type()