rs · rs · Mar 31, 2019 · Mar 28, 2019
diff --git a/b/README.md b/b/README.md
@@ -0,0 +1,4 @@
+# Bytes storage
+
+This subpackage is there to allow storage of XIDs in a binary format in, for example, a database.
+It allows some data size optimisation as the 12 bytes will be smaller to store than a string.
diff --git a/b/id.go b/b/id.go
@@ -0,0 +1,38 @@
+package xidb
+
+import (
+	"database/sql/driver"
+	"fmt"
+
+	"github.com/rs/xid"
+)
+
+type ID struct {
+	xid.ID
+}
+
+// Value implements the driver.Valuer interface.
+func (id ID) Value() (driver.Value, error) {
+	if id.ID.IsNil() {
+		return nil, nil
+	}
+	return id.ID[:], nil
+}
+
+// Scan implements the sql.Scanner interface.
+func (id *ID) Scan(value interface{}) (err error) {
+	switch val := value.(type) {
+	case []byte:
+		i, err := xid.FromBytes(val)
+		if err != nil {
+			return err
+		}
+		*id = ID{ID: i}
+		return nil
+	case nil:
+		*id = ID{ID: xid.NilID()}
+		return nil
+	default:
+		return fmt.Errorf("xid: scanning unsupported type: %T", value)
+	}
+}
diff --git a/b/id_test.go b/b/id_test.go
@@ -0,0 +1,86 @@
+package xidb
+
+import (
+	"reflect"
+	"testing"
+
+	"github.com/rs/xid"
+)
+
+func TestIDValue(t *testing.T) {
+	i, _ := xid.FromString("9m4e2mr0ui3e8a215n4g")
+
+	tests := []struct {
+		name        string
+		id          ID
+		expectedVal interface{}
+	}{
+		{
+			name:        "non nil id",
+			id:          ID{ID: i},
+			expectedVal: i.Bytes(),
+		},
+		{
+			name:        "nil id",
+			id:          ID{ID: xid.NilID()},
+			expectedVal: nil,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got, _ := tt.id.Value()
+			if !reflect.DeepEqual(got, tt.expectedVal) {
+				t.Errorf("wanted %v, got %v", tt.expectedVal, got)
+			}
+		})
+	}
+}
+
+func TestIDScan(t *testing.T) {
+	i, _ := xid.FromString("9m4e2mr0ui3e8a215n4g")
+
+	tests := []struct {
+		name        string
+		val         interface{}
+		expectedID  ID
+		expectedErr bool
+	}{
+		{
+			name:       "bytes id",
+			val:        i.Bytes(),
+			expectedID: ID{ID: i},
+		},
+		{
+			name:       "nil id",
+			val:        nil,
+			expectedID: ID{ID: xid.NilID()},
+		},
+		{
+			name:        "wrong bytes",
+			val:         []byte{0x01},
+			expectedErr: true,
+		},
+		{
+			name:        "unknown type",
+			val:         1,
+			expectedErr: true,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			id := &ID{}
+			err := id.Scan(tt.val)
+			if (err != nil) != tt.expectedErr {
+				t.Errorf("error expected: %t, got %t", tt.expectedErr, (err != nil))
+			}
+			if err == nil {
+				if !reflect.DeepEqual(id.ID, tt.expectedID.ID) {
+					t.Errorf("wanted %v, got %v", tt.expectedID, id)
+				}
+			}
+
+		})
+	}
+}