[usage] Handle empty value varchar time, use ISO8601

components/usage/pkg/db/types.go

@@ -39,37 +39,36 @@ func (n *VarcharTime) Scan(value interface{}) error {
 
 	switch s := value.(type) {
 	case []uint8:
-		// Null value - empty string mean value is not set
-		if len(s) == 0 {
-			n.valid = false
-			return nil
-		}
-
-		parsed, err := iso8601.ParseString(string(s))
-		if err != nil {
-			return fmt.Errorf("failed to parse %v into ISO8601: %w", string(s), err)
-		}
-		n.valid = true
-		n.t = parsed.UTC()
-		return nil
+		return n.parseString(string(s))
 	case string:
-		if len(s) == 0 {
-			n.valid = false
-			return nil
-		}
-
-		parsed, err := iso8601.ParseString(s)
-		if err != nil {
-			return fmt.Errorf("failed to parse %v into ISO8601: %w", s, err)
-		}
-
-		n.valid = true
-		n.t = parsed.UTC()
-		return nil
+		return n.parseString(s)
 	}
 	return fmt.Errorf("unknown scan value for VarcharTime with value: %v", value)
 }
 
+func (n *VarcharTime) parseString(s string) error {
+	// Null value - empty string mean value is not set
+	if len(s) == 0 {
+		n.valid = false
+		return nil
+	}
+
+	parsed, err := iso8601.ParseString(s)
+	if err != nil {
+		return fmt.Errorf("failed to parse %v into ISO8601: %w", s, err)
+	}
+
+	if parsed.UTC().IsZero() {
+		n.t = time.Time{}.UTC()
+		n.valid = false
+		return nil
+	}
+
+	n.valid = true
+	n.t = parsed.UTC()
+	return nil
+}
+
 func (n VarcharTime) Time() time.Time {
 	return n.t
 }
@@ -80,9 +79,21 @@ func (n VarcharTime) IsSet() bool {
 
 // Value implements the driver Valuer interface.
 func (n VarcharTime) Value() (driver.Value, error) {
-	return n.t.UTC().Format(time.RFC3339Nano), nil
+	if n.IsSet() {
+		return TimeToISO8601(n.t), nil
+	}
+	return "", nil
 }
 
 func (n VarcharTime) String() string {
-	return n.t.Format(time.RFC3339Nano)
+	if n.IsSet() {
+		return TimeToISO8601(n.t)
+	}
+	return ""
+}
+
+const ISO8601Format = "2006-01-02T15:04:05.000Z"
+
+func TimeToISO8601(t time.Time) string {
+	return t.UTC().Format(ISO8601Format)
 }

components/usage/pkg/db/types_test.go

@@ -6,6 +6,7 @@ package db
 
 import (
 	"github.com/stretchr/testify/require"
+	"gorm.io/gorm"
 	"testing"
 	"time"
 )
@@ -77,3 +78,81 @@ func TestVarcharTime_Scan(t *testing.T) {
 		})
 	}
 }
+
+func TestVarcharTime_Value_ISO8601(t *testing.T) {
+	for _, scenario := range []struct {
+		Time     VarcharTime
+		Expected string
+	}{
+		{
+			Time:     NewVarcharTime(time.Date(2019, 05, 10, 9, 54, 28, 185000000, time.UTC)),
+			Expected: "2019-05-10T09:54:28.185Z",
+		},
+		{
+			Time:     VarcharTime{},
+			Expected: "",
+		},
+	} {
+		wireFormat, err := scenario.Time.Value()
+		require.NoError(t, err)
+		require.Equal(t, scenario.Expected, wireFormat)
+	}
+}
+
+func TestVarcharTime_String_ISO8601(t *testing.T) {
+	for _, scenario := range []struct {
+		Time     VarcharTime
+		Expected string
+	}{
+		{
+			Time:     NewVarcharTime(time.Date(2019, 05, 10, 9, 54, 28, 185000000, time.UTC)),
+			Expected: "2019-05-10T09:54:28.185Z",
+		},
+		{
+			Time:     VarcharTime{},
+			Expected: "",
+		},
+	} {
+		require.Equal(t, scenario.Expected, scenario.Time.String())
+	}
+}
+
+func TestVarcharTime_SerializeAndDeserialize(t *testing.T) {
+	// Custom table to be able to exercise serialization easily, independent of other models
+	type VarcharModel struct {
+		ID   int         `gorm:"primaryKey"`
+		Time VarcharTime `gorm:"column:time;type:varchar(255);"`
+	}
+
+	conn := ConnectForTests(t)
+	require.NoError(t, conn.AutoMigrate(&VarcharModel{}))
+
+	conn.Session(&gorm.Session{AllowGlobalUpdate: true}).Delete(&VarcharModel{})
+
+	for _, scenario := range []struct {
+		Description string
+		Input       VarcharModel
+		Expected    VarcharModel
+	}{
+		{
+			Description: "empty value for VarcharTime",
+			Input: VarcharModel{
+				ID:   1,
+				Time: VarcharTime{},
+			},
+			Expected: VarcharModel{
+				ID:   1,
+				Time: VarcharTime{},
+			},
+		},
+	} {
+		tx := conn.Create(scenario.Input)
+		require.NoError(t, tx.Error)
+
+		var read VarcharModel
+		tx = conn.First(&read, scenario.Input.ID)
+		require.NoError(t, tx.Error)
+
+		require.Equal(t, scenario.Expected, read)
+	}
+}