From cdeab1a0db29fa02acf7f8d01d70024869051100 Mon Sep 17 00:00:00 2001
From: Felix Sun <sunfmin@gmail.com>
Date: Sat, 11 Sep 2021 14:48:51 +0800
Subject: [PATCH] Be able to set nil

---
 example_test.go   |  2 +-
 go.mod            |  3 +++
 map_slice_test.go | 57 +++++++++++++++++++++++++++++++++++++++++++++++
 set.go            |  6 +++++
 4 files changed, 67 insertions(+), 1 deletion(-)
 create mode 100644 go.mod

diff --git a/example_test.go b/example_test.go
index 138f82f..6ddab35 100644
--- a/example_test.go
+++ b/example_test.go
@@ -303,7 +303,7 @@ func ExampleSet_7notexists() {
 
 	fmt.Println(err)
 	//Output:
-	// no such field.
+	// no such field
 }
 
 
diff --git a/go.mod b/go.mod
new file mode 100644
index 0000000..ff3743d
--- /dev/null
+++ b/go.mod
@@ -0,0 +1,3 @@
+module github.com/sunfmin/reflectutils
+
+go 1.17
diff --git a/map_slice_test.go b/map_slice_test.go
index 5628368..ee4619a 100644
--- a/map_slice_test.go
+++ b/map_slice_test.go
@@ -71,3 +71,60 @@ func TestSlices(t *testing.T) {
 	}
 
 }
+
+func TestMapSetNil(t *testing.T) {
+	m := make(map[string]int)
+	Set(&m, "", nil)
+	if m != nil {
+		t.Errorf("got non-nil (%p), want nil", m)
+	}
+}
+
+func TestSliceSetNil(t *testing.T) {
+	m := []int{1}
+	err := Set(&m, "", nil)
+	if err != nil {
+		panic(err)
+	}
+	if m != nil {
+		t.Errorf("got non-nil (%p), want nil", m)
+	}
+
+}
+
+func TestStructSetNil(t *testing.T) {
+	type S struct {
+		Val string
+	}
+	m := &S{Val: "123"}
+	err := Set(&m, "", nil)
+	if err != nil {
+		panic(err)
+	}
+
+
+	if m != nil {
+		t.Errorf("got non-nil (%#+v), want nil", m)
+	}
+}
+
+func TestSetFieldNil(t *testing.T) {
+
+	type S struct {
+		Value []int
+	}
+
+	var s = &S{
+		Value: []int{1, 2},
+	}
+
+	err := Set(s, "Value", nil)
+	if err != nil {
+		panic(err)
+	}
+
+	if s.Value != nil {
+		panic("s.Value is not nil")
+	}
+
+}
\ No newline at end of file
diff --git a/set.go b/set.go
index 5f14240..f994bf5 100644
--- a/set.go
+++ b/set.go
@@ -63,6 +63,12 @@ func Set(i interface{}, name string, value interface{}) (err error) {
 				return
 			}
 		default:
+			if value == nil {
+				vm := reflect.ValueOf(i)
+				vm.Elem().Set(reflect.Zero(vm.Elem().Type()))
+				return
+			}
+
 			valv := reflect.ValueOf(value)
 			for valv.Kind() == reflect.Ptr {
 				valv = valv.Elem()