pw_console/embedding.rst

.. _module-pw_console-embedding:

Embedding Guide
===============

Using embed()
-------------

``pw console`` is invoked by calling ``PwConsoleEmbed().embed()`` in your
own Python script.

.. automodule:: pw_console.embed
    :members: PwConsoleEmbed
    :undoc-members:
    :show-inheritance:

Adding Log Metadata
-------------------

``pw_console`` can display log messages in a table with justified columns for
metadata fields provided by :ref:`module-pw_log_tokenized`.

It is also possible to manually add values that should be displayed in columns
using the ``extra`` keyword argument when logging from Python. See the `Python's
logging documentation`_ for how ``extra`` works. A dict of name, value pairs can
be passed in as the ``extra_metadata_fields`` variable. For example, the
following code will create a log message with two custom columns titled
``module`` and ``timestamp``.

.. code-block:: python

  import logging

  LOG = logging.getLogger('log_source_1')

  LOG.info(
      'Hello there!',
      extra={
          'extra_metadata_fields': {
              'module': 'cool',
              'timestamp': 1.2345,
          }
      }
  )

.. _Python's logging documentation: https://docs.python.org/3/library/logging.html#logging.Logger.debug

Debugging Serial Data
---------------------

``pw_console`` is often used to communicate with devices using `pySerial
<https://pythonhosted.org/pyserial/>`_ and it may be necessary to monitor the
raw data flowing over the wire to help with debugging. ``pw_console`` provides a
simple wrapper for a pySerial instances that log data for each read and write
call.

.. code-block:: python

   # Instead of 'import serial' use this import:
   from pw_console.pyserial_wrapper import SerialWithLogging

   serial_device = SerialWithLogging('/dev/ttyUSB0', 115200, timeout=1)

With the above example each ``serial_device.read`` and ``write`` call will
create a log message to the ``pw_console.serial_debug_logger`` Python
logger. This logger can then be included as a log window pane in the
``PwConsoleEmbed()`` call.

.. code-block:: python

   import logging
   from pw_console import PwConsoleEmbed

   console = PwConsoleEmbed(
       global_vars=globals(),
       local_vars=locals(),
       loggers={
           'Host Logs': [
               # Root Python logger
               logging.getLogger(''),
               # Your current Python package logger.
               logging.getLogger(__package__)
           ],
           'Device Logs': [
               logging.getLogger('usb_gadget')
           ],
           'Serial Debug': [
               # New log window to display serial read and writes
               logging.getLogger('pw_console.serial_debug_logger')
           ],
       },
       app_title='CoolConsole',
   )
   # Then run the console with:
   console.embed()

.. figure:: images/serial_debug.svg
  :alt: Serial debug pw_console screenshot.

  Screenshot of issuing an Echo RPC with serial debug logging.