Merge pull request #119 from math-nao/master

Add support to copy from a nil slice pointer to a slice field when DeepCopy is enabled

copier.go

@@ -436,6 +436,9 @@ func set(to, from reflect.Value, deepCopy bool) bool {
 					toKind = reflect.TypeOf(to.Interface()).Kind()
 				}
 			}
+			if from.Kind() == reflect.Ptr && from.IsNil() {
+				return true
+			}
 			if toKind == reflect.Struct || toKind == reflect.Map || toKind == reflect.Slice {
 				return false
 			}

copier_test.go

@@ -334,10 +334,14 @@ func TestStructField(t *testing.T) {
 	type UserWithDetailsPtr struct {
 		Details []*Detail
 		Detail  *Detail
+		Notes   *[]string
+		Notes2  *[]string
 	}
 	type UserWithDetails struct {
 		Details []Detail
 		Detail  Detail
+		Notes   []string
+		Notes2  []string
 	}
 	type UserWithSimilarDetailsPtr struct {
 		Detail *SimilarDetail
@@ -389,7 +393,7 @@ func TestStructField(t *testing.T) {
 				t.Fatalf("DeepCopy not enabled")
 			}
 
-			if len(to.Details) != len(to.Details) {
+			if len(from.Details) != len(to.Details) {
 				t.Fatalf("slice should be copied")
 			}
 
@@ -414,7 +418,7 @@ func TestStructField(t *testing.T) {
 				t.Fatalf("DeepCopy not enabled")
 			}
 
-			if len(to.Details) != len(to.Details) {
+			if len(from.Details) != len(to.Details) {
 				t.Fatalf("slice should be copied")
 			}
 
@@ -502,6 +506,27 @@ func TestStructField(t *testing.T) {
 				t.Errorf("should be different")
 			}
 		})
+
+		t.Run("Should work with from a nil ptr slice field to a slice field", func(t *testing.T) {
+			notes := []string{"hello", "world"}
+			from := UserWithDetailsPtr{Notes: &notes, Notes2: nil}
+			to := UserWithDetails{}
+			err := copier.Copy(&to, from)
+			if err != nil {
+				t.Errorf("should not return an error")
+				return
+			}
+
+			if len(to.Notes) != len(*from.Notes) {
+				t.Errorf("should be the same length")
+			}
+			if to.Notes[0] != (*from.Notes)[0] {
+				t.Errorf("should be the same")
+			}
+			if to.Notes[1] != (*from.Notes)[1] {
+				t.Errorf("should be the same")
+			}
+		})
 	})
 
 	t.Run("Should work with deepCopy", func(t *testing.T) {
@@ -521,7 +546,7 @@ func TestStructField(t *testing.T) {
 				t.Fatalf("DeepCopy enabled")
 			}
 
-			if len(to.Details) != len(to.Details) {
+			if len(from.Details) != len(to.Details) {
 				t.Fatalf("slice should be copied")
 			}
 
@@ -545,7 +570,7 @@ func TestStructField(t *testing.T) {
 				t.Fatalf("DeepCopy enabled")
 			}
 
-			if len(to.Details) != len(to.Details) {
+			if len(from.Details) != len(to.Details) {
 				t.Fatalf("slice should be copied")
 			}
 
@@ -633,6 +658,37 @@ func TestStructField(t *testing.T) {
 				t.Errorf("should be different")
 			}
 		})
+
+		t.Run("Should work with from a nil ptr slice field to a slice field", func(t *testing.T) {
+			notes := []string{"hello", "world"}
+			from := UserWithDetailsPtr{Notes: &notes, Notes2: nil}
+			to := UserWithDetails{}
+			err := copier.CopyWithOption(&to, from, optionsDeepCopy)
+			if err != nil {
+				t.Errorf("should not return an error")
+				return
+			}
+
+			if len(to.Notes) != len(*from.Notes) {
+				t.Errorf("should be the same length")
+			}
+			if to.Notes[0] != (*from.Notes)[0] {
+				t.Errorf("should be the same")
+			}
+			if to.Notes[1] != (*from.Notes)[1] {
+				t.Errorf("should be the same")
+			}
+
+			newValue := []string{"new", "value"}
+			to.Notes = newValue
+
+			if to.Notes[0] == (*from.Notes)[0] {
+				t.Errorf("should be different")
+			}
+			if to.Notes[1] == (*from.Notes)[1] {
+				t.Errorf("should be different")
+			}
+		})
 	})
 }