Handle driver.Valuers inside Map.Encode

pgtype/pgtype.go

@@ -1720,6 +1720,17 @@ func (m *Map) Encode(oid uint32, formatCode int16, value interface{}, buf []byte
 
 	plan := m.PlanEncode(oid, formatCode, value)
 	if plan == nil {
+		if dv, ok := value.(driver.Valuer); ok {
+			if dv == nil {
+				return nil, nil
+			}
+			v, err := dv.Value()
+			if err != nil {
+				return nil, err
+			}
+			return m.Encode(oid, formatCode, v, buf)
+		}
+
 		return nil, fmt.Errorf("unable to encode %#v into OID %d", value, oid)
 	}
 	return plan.Encode(value, buf)