Add support for custom JSON encoders

[tintoy]

Relates to #7 and #13.

SeqLogHander constructor now takes an additional (optional) keyword argument called json_encoder_class which is a class that derives from json.encoder.JSONEncoder (see here under "Extending JSONEncoder" for details).

CC: @snailkn @blint587

[snailkn]

the default handler config will just parse json_encoder_class to a str, so I think should add some specific code to parse the json_encoder_class to a class

[tintoy]

Oh, nice catch! I was under the (apparently mistaken) impression it was smart enough to recognise class names. I'll sort that out, thanks :)

[tintoy]

I think this might do it:

def get_logger_class_by_name(name):
  return reduce(getattr, name.split("."), sys.modules[__name__])

[tintoy]

Oops - need some sleep; that's trying to be too clever, but yeah I can see how to resolve the class name. Will add functionality for it.

[tintoy]

Something like this:

import importlib

def get_class_by_name(name):
    name_parts = name.split('.')
    module_name = '.'.join(
        name_parts[:-1]
    )
    target_module = importlib.import_module(module_name)

    class_name = name_parts[-1:]
    target_class = getattr(target_module, class_name)

    return target_class

Will have a proper look at it tomorrow though once I've had some sleep

[tintoy]

How does 167eb72 look?

[snailkn]

I have use several code to fix this bug:

def configure_from_file(file_name, override_root_logger=True, use_structured_logger=True):
    """your comment"""
    with open(file_name) as config_file:
        config = yaml.load(config_file)
    for name, handler in config.get('handlers', {}).items():
        if 'json_encoder_class' in handler:
            json_encoder_config = logging.config.BaseConfigurator({})
            config['handlers'][name]['json_encoder_class'] = json_encoder_config.resolve(handler['json_encoder_class'])

    configure_from_dict(config, override_root_logger)

I use the BaseConfigurator define in logging.config to replace the function get_class_by_name, because I think use the build_in module could avoid some unexpected bug

[tintoy]

Interesting, I'll give that a try, thanks!

[snailkn]

I think it's a good idea to confirm a class is a subclass of json.encoder.JSONEncoder,
I marked two lines which is not passed in my app and I hope you can confirm them.
I also run some test and it will raise the expected error when I use a class which is a invalid class string or it is not a subclass of json.encoder.JSONEncoder

thank you
by snailkn

[snailkn]

target_class_name will be a list, should be :
target_class_name = name_parts[-1]

[tintoy]

Oops! Yes, sorry I'll fix that up and merge this morning!

[tintoy]

I'll add some tests for this functionality as well.

[tintoy]

Published v0.3.11.