Change in pysim[master]: extend JSONEncoder to serialze 'bytes' style objects as hex strings

laforge gerrit-no-reply at
Sat Apr 10 16:41:27 UTC 2021

laforge has uploaded this change for review. ( )

Change subject: extend JSONEncoder to serialze 'bytes' style objects as hex strings

extend JSONEncoder to serialze 'bytes' style objects as hex strings

This means we can skip a lot of code that manually converts from
bytes to hex before JSON serialization.

Change-Id: I9c9eff0556d9d196e64553b5276e162f69d0c18f
M pySim/
2 files changed, 13 insertions(+), 3 deletions(-)

  git pull ssh:// refs/changes/02/23702/1

diff --git a/ b/
index ce1b3bf..1d81eb8 100755
--- a/
+++ b/
@@ -39,7 +39,7 @@
 from pySim.commands import SimCardCommands
 from pySim.transport import init_reader, ApduTracer
 from import card_detect, Card
-from pySim.utils import h2b, swap_nibbles, rpad, h2s
+from pySim.utils import h2b, swap_nibbles, rpad, h2s, JsonEncoder
 from pySim.utils import dec_st, sanitize_pin_adm, tabulate_str_list, is_hex
 from pySim.card_handler import card_handler
@@ -81,9 +81,9 @@
 	def poutput_json(self, data, force_no_pretty = False):
 		"""line cmd2.putput() but for a json serializable dict."""
 		if force_no_pretty or self.json_pretty_print == False:
-			output = json.dumps(data)
+			output = json.dumps(data, cls=JsonEncoder)
-			output = json.dumps(data, indent=4)
+			output = json.dumps(data, cls=JsonEncoder, indent=4)
 	def _onchange_numeric_path(self, param_name, old, new):
diff --git a/pySim/ b/pySim/
index 6a093fa..5f66170 100644
--- a/pySim/
+++ b/pySim/
@@ -3,9 +3,12 @@
 """ pySim: various utilities
+import json
+from io import BytesIO
 from typing import Optional, List, Dict, Any, Tuple
 # Copyright (C) 2009-2010  Sylvain Munaut <tnt at>
+# Copyright (C) 2021 Harald Welte <laforge at>
 # This program is free software: you can redistribute it and/or modify
 # it under the terms of the GNU General Public License as published by
@@ -831,3 +834,10 @@
 		format_str_row = (" " * lspace) + format_str_row
 		table.append(format_str_row % tuple(str_list_row))
 	return '\n'.join(table)
+class JsonEncoder(json.JSONEncoder):
+    """Extend the standard library JSONEncoder with support for more types."""
+    def default(self, o):
+        if isinstance(o, BytesIO) or isinstance(o, bytes) or isinstance(o, bytearray):
+            return b2h(o)
+        return json.JSONEncoder.default(self, o)

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Gerrit-Project: pysim
Gerrit-Branch: master
Gerrit-Change-Id: I9c9eff0556d9d196e64553b5276e162f69d0c18f
Gerrit-Change-Number: 23702
Gerrit-PatchSet: 1
Gerrit-Owner: laforge <laforge at>
Gerrit-MessageType: newchange
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