fix apply with nil value (#8)

Author: Mochamad Sohibul Iman

changeset.go

@@ -87,7 +87,7 @@ func (c *Changeset) Apply(doc *rel.Document, mut *rel.Mutation) {
 				c.applyAssocMany(doc, field, mut, v)
 			}
 		default:
-			if field != pField && v != nil && scannable(c.types[field]) {
+			if field != pField && scannable(c.types[field]) {
 				c.set(doc, mut, field, v)
 			}
 		}

changeset_test.go

@@ -19,6 +19,7 @@ type User struct {
 	Address      Address
 	CreatedAt    time.Time
 	UpdatedAt    time.Time
+	DeletedAt    *time.Time
 }
 
 type Transaction struct {
@@ -123,6 +124,7 @@ func TestChangesetApply(t *testing.T) {
 			rel.Set("age", 20),
 			rel.Set("created_at", now),
 			rel.Set("updated_at", now),
+			rel.Set("deleted_at", nil),
 		)
 		transaction1Mutation = rel.Apply(rel.NewDocument(&Transaction{}),
 			rel.Set("item", "Sword"),
@@ -149,6 +151,8 @@ func TestChangesetApply(t *testing.T) {
 		return ch
 	})
 
+	PutChange(ch, "deleted_at", nil)
+
 	userMutation.SetAssoc("transactions", transaction1Mutation, transaction2Mutation)
 	userMutation.SetAssoc("address", addressMutation)