fix string to time conversion

Author: siherrmann

helper/time.go

@@ -24,32 +24,27 @@ func UnixStringToTime(in string) (time.Time, error) {
 }
 
 // ISO8601StringToTime converts an ISO8601 date string to a time.Time object.
-// It checks the format of the string and parses it accordingly.
-// It supports various formats including local time, UTC time, with and without microseconds.
+// It supports RFC3339 format timestamps including timezone offsets,
+// as well as database formats without timezone information.
 func ISO8601StringToTime(in string) (time.Time, error) {
-	layout := ""
-	// Iso8601 date string in local time (yyyy-MM-ddTHH:mm:ss.mmmuuu)
-	match, _ := regexp.MatchString("^[-:.T0-9]{26}$", in)
-	if match {
-		layout = "2006-01-02T15:04:05.000000"
+	// RFC3339Nano handles all formats with timezone (Z or +/-HH:MM) including nanoseconds
+	// Examples: 2026-01-19T14:37:45.673212+01:00, 2026-01-19T14:37:45.123Z, 2026-01-19T14:37:45Z
+	if date, err := time.Parse(time.RFC3339Nano, in); err == nil {
+		return date, nil
 	}
-
-	// Iso8601 date string in UTC time (yyyy-MM-ddTHH:mm:ss.mmmuuuZ)
-	match, _ = regexp.MatchString("^[-:.T0-9]{26}Z$", in)
-	if match {
-		layout = "2006-01-02T15:04:05.000000Z"
+	if date, err := time.Parse(time.RFC3339, in); err == nil {
+		return date, nil
 	}
 
-	// Iso8601 date string in local time without microseconds (yyyy-MM-ddTHH:mm:ss.mmm)
-	match, _ = regexp.MatchString("^[-:.T0-9]{23}$", in)
-	if match {
+	// Database formats without timezone - local time only
+	layout := ""
+	switch len(in) {
+	case 26: // yyyy-MM-ddTHH:mm:ss.mmmuuu (microseconds)
+		layout = "2006-01-02T15:04:05.000000"
+	case 23: // yyyy-MM-ddTHH:mm:ss.mmm (milliseconds)
 		layout = "2006-01-02T15:04:05.000"
-	}
-
-	// Iso8601 date string in UTC time without microseconds (yyyy-MM-ddTHH:mm:ss.mmmZ)
-	match, _ = regexp.MatchString("^[-:.T0-9]{23}Z$", in)
-	if match {
-		layout = "2006-01-02T15:04:05.000Z"
+	default:
+		return time.Time{}, fmt.Errorf("error parsing iso8601 string to time: unsupported format")
 	}
 
 	date, err := time.Parse(layout, in)

helper/time_test.go

@@ -0,0 +1,121 @@
+package helper
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestISO8601StringToTime(t *testing.T) {
+	tests := []struct {
+		name      string
+		input     string
+		wantError bool
+	}{
+		{
+			name:      "RFC3339 with timezone offset and nanoseconds",
+			input:     "2026-01-19T14:37:45.673212+01:00",
+			wantError: false,
+		},
+		{
+			name:      "RFC3339 with Z suffix",
+			input:     "2026-01-19T14:37:45Z",
+			wantError: false,
+		},
+		{
+			name:      "RFC3339 with Z suffix and nanoseconds",
+			input:     "2026-01-19T14:37:45.123456789Z",
+			wantError: false,
+		},
+		{
+			name:      "Zero time with Z suffix",
+			input:     "0001-01-01T00:00:00Z",
+			wantError: false,
+		},
+		{
+			name:      "RFC3339 with negative timezone offset",
+			input:     "2026-01-19T14:37:45-05:00",
+			wantError: false,
+		},
+		{
+			name:      "DB format - local time with microseconds",
+			input:     "2026-01-19T14:37:45.123456",
+			wantError: false,
+		},
+		{
+			name:      "DB format - UTC time with microseconds",
+			input:     "2026-01-19T14:37:45.123456Z",
+			wantError: false,
+		},
+		{
+			name:      "DB format - local time with milliseconds",
+			input:     "2026-01-19T14:37:45.123",
+			wantError: false,
+		},
+		{
+			name:      "DB format - UTC time with milliseconds",
+			input:     "2026-01-19T14:37:45.123Z",
+			wantError: false,
+		},
+		{
+			name:      "Invalid format",
+			input:     "not-a-date",
+			wantError: true,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			result, err := ISO8601StringToTime(tt.input)
+			if tt.wantError {
+				assert.Error(t, err)
+				return
+			}
+
+			assert.NoError(t, err)
+			assert.False(t, result.IsZero() && tt.input != "0001-01-01T00:00:00Z")
+		})
+	}
+}
+
+func TestUnixStringToTime(t *testing.T) {
+	tests := []struct {
+		name      string
+		input     string
+		wantError bool
+	}{
+		{
+			name:      "Valid Unix timestamp",
+			input:     "1737292665",
+			wantError: false,
+		},
+		{
+			name:      "Zero timestamp",
+			input:     "0",
+			wantError: false,
+		},
+		{
+			name:      "Invalid format with letters",
+			input:     "12345abc",
+			wantError: true,
+		},
+		{
+			name:      "Empty string",
+			input:     "",
+			wantError: true,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			result, err := UnixStringToTime(tt.input)
+			if tt.wantError {
+				assert.Error(t, err)
+				return
+			}
+
+			assert.NoError(t, err)
+			assert.False(t, result.IsZero() && tt.input != "0")
+		})
+	}
+}