Handle zip file modification (#877)

* Rescan zip if updating mod time
* Use inequality for mod time comparison
* Add sort by file_mod_time (fixes #469)

pkg/models/sqlite_timestamp.go

@@ -19,3 +19,31 @@ func (t *SQLiteTimestamp) Scan(value interface{}) error {
 func (t SQLiteTimestamp) Value() (driver.Value, error) {
 	return t.Timestamp.Format(time.RFC3339), nil
 }
+
+type NullSQLiteTimestamp struct {
+	Timestamp time.Time
+	Valid     bool
+}
+
+// Scan implements the Scanner interface.
+func (t *NullSQLiteTimestamp) Scan(value interface{}) error {
+	var ok bool
+	t.Timestamp, ok = value.(time.Time)
+	if !ok {
+		t.Timestamp = time.Time{}
+		t.Valid = false
+		return nil
+	}
+
+	t.Valid = true
+	return nil
+}
+
+// Value implements the driver Valuer interface.
+func (t NullSQLiteTimestamp) Value() (driver.Value, error) {
+	if t.Timestamp.IsZero() {
+		return nil, nil
+	}
+
+	return t.Timestamp.Format(time.RFC3339), nil
+}