From d04a036fb5982f260c62ad949723d193d4e0722a Mon Sep 17 00:00:00 2001
From: Shi Han NG <shihanng@gmail.com>
Date: Fri, 2 Aug 2019 17:11:23 +0900
Subject: [PATCH] Implement unique=FieldName

---
 baked_in.go       | 18 ++++++++++++++++--
 validator_test.go | 43 +++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 59 insertions(+), 2 deletions(-)

diff --git a/baked_in.go b/baked_in.go
index 338cddd..fcfea88 100644
--- a/baked_in.go
+++ b/baked_in.go
@@ -224,14 +224,28 @@ func isOneOf(fl FieldLevel) bool {
 func isUnique(fl FieldLevel) bool {
 
 	field := fl.Field()
+	param := fl.Param()
 	v := reflect.ValueOf(struct{}{})
 
 	switch field.Kind() {
 	case reflect.Slice, reflect.Array:
-		m := reflect.MakeMap(reflect.MapOf(field.Type().Elem(), v.Type()))
+		if param == "" {
+			m := reflect.MakeMap(reflect.MapOf(field.Type().Elem(), v.Type()))
+
+			for i := 0; i < field.Len(); i++ {
+				m.SetMapIndex(field.Index(i), v)
+			}
+			return field.Len() == m.Len()
+		}
+
+		sf, ok := field.Type().Elem().FieldByName(param)
+		if !ok {
+			panic(fmt.Sprintf("Bad field name %s", param))
+		}
 
+		m := reflect.MakeMap(reflect.MapOf(sf.Type, v.Type()))
 		for i := 0; i < field.Len(); i++ {
-			m.SetMapIndex(field.Index(i), v)
+			m.SetMapIndex(field.Index(i).FieldByName(param), v)
 		}
 		return field.Len() == m.Len()
 	case reflect.Map:
diff --git a/validator_test.go b/validator_test.go
index a8ccfaa..11fb375 100644
--- a/validator_test.go
+++ b/validator_test.go
@@ -8160,6 +8160,49 @@ func TestUniqueValidation(t *testing.T) {
 	PanicMatches(t, func() { validate.Var(1.0, "unique") }, "Bad field type float64")
 }
 
+func TestUniqueValidationStructSlice(t *testing.T) {
+	testStructs := []struct {
+		A string
+		B string
+	}{
+		{A: "one", B: "two"},
+		{A: "one", B: "three"},
+	}
+
+	tests := []struct {
+		target   interface{}
+		param    string
+		expected bool
+	}{
+		{testStructs, "unique", true},
+		{testStructs, "unique=A", false},
+		{testStructs, "unique=B", true},
+	}
+
+	validate := New()
+
+	for i, test := range tests {
+
+		errs := validate.Var(test.target, test.param)
+
+		if test.expected {
+			if !IsEqual(errs, nil) {
+				t.Fatalf("Index: %d unique failed Error: %v", i, errs)
+			}
+		} else {
+			if IsEqual(errs, nil) {
+				t.Fatalf("Index: %d unique failed Error: %v", i, errs)
+			} else {
+				val := getError(errs, "", "")
+				if val.Tag() != "unique" {
+					t.Fatalf("Index: %d unique failed Error: %v", i, errs)
+				}
+			}
+		}
+	}
+	PanicMatches(t, func() { validate.Var(testStructs, "unique=C") }, "Bad field name C")
+}
+
 func TestHTMLValidation(t *testing.T) {
 	tests := []struct {
 		param    string