From 6c0ee2700a1282fe0e2eb669cf57641f01fcf9bc Mon Sep 17 00:00:00 2001
From: Jinzhu <wosmvp@gmail.com>
Date: Wed, 30 Dec 2020 10:42:13 +0800
Subject: [PATCH] Allow to use Valuer with Eq expression, #3899

---
 clause/expression.go      |  4 ++++
 clause/expression_test.go | 11 ++++++-----
 2 files changed, 10 insertions(+), 5 deletions(-)

diff --git a/clause/expression.go b/clause/expression.go
index 3844d66b..7a4c09f4 100644
--- a/clause/expression.go
+++ b/clause/expression.go
@@ -301,6 +301,10 @@ func (like Like) NegationBuild(builder Builder) {
 }
 
 func eqNil(value interface{}) bool {
+	if valuer, ok := value.(driver.Valuer); ok {
+		value, _ = valuer.Value()
+	}
+
 	return value == nil || eqNilReflect(value)
 }
 
diff --git a/clause/expression_test.go b/clause/expression_test.go
index 9e3d7bad..4472bdb1 100644
--- a/clause/expression_test.go
+++ b/clause/expression_test.go
@@ -105,28 +105,29 @@ func TestNamedExpr(t *testing.T) {
 func TestExpression(t *testing.T) {
 	column := "column-name"
 	results := []struct {
-		Expressions    []clause.Expression
-		Result string
+		Expressions []clause.Expression
+		Result      string
 	}{{
 		Expressions: []clause.Expression{
 			clause.Eq{Column: column, Value: "column-value"},
 		},
 		Result: "`column-name` = ?",
-	},{
+	}, {
 		Expressions: []clause.Expression{
 			clause.Eq{Column: column, Value: nil},
 			clause.Eq{Column: column, Value: (*string)(nil)},
 			clause.Eq{Column: column, Value: (*int)(nil)},
 			clause.Eq{Column: column, Value: (*bool)(nil)},
 			clause.Eq{Column: column, Value: (interface{})(nil)},
+			clause.Eq{Column: column, Value: sql.NullString{String: "", Valid: false}},
 		},
 		Result: "`column-name` IS NULL",
-	},{
+	}, {
 		Expressions: []clause.Expression{
 			clause.Neq{Column: column, Value: "column-value"},
 		},
 		Result: "`column-name` <> ?",
-	},{
+	}, {
 		Expressions: []clause.Expression{
 			clause.Neq{Column: column, Value: nil},
 			clause.Neq{Column: column, Value: (*string)(nil)},