/usr/lib/python3/dist-packages/cement/ext/ext_json.py is in python3-cement 2.10.0-1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 | """
The JSON Extension adds the :class:`JsonOutputHandler` to render
output in pure JSON, as well as the :class:`JsonConfigHandler` that allows
applications to use JSON configuration files as a drop-in replacement of
the default :class:`cement.ext.ext_configparser.ConfigParserConfigHandler`.
Requirements
------------
* No external dependencies.
Configuration
-------------
This extension does not support any configuration settings.
Usage
_____
**myapp.conf**
.. code-block:: json
{
"myapp": {
"foo": "bar"
}
}
**myapp.py**
.. code-block:: python
from cement.core.foundation import CementApp
class MyApp(CementApp):
class Meta:
label = 'myapp'
extensions = ['json']
config_handler = 'json'
# you probably don't want this to be json by default.. but you can
# output_handler = 'json'
with MyApp() as app:
app.run()
# create some data
data = dict(foo=app.config.get('myapp', 'foo'))
app.render(data)
In general, you likely would not set ``output_handler`` to ``json``, but
rather another type of output handler that display readable output to the
end-user (i.e. Mustache, Genshi, or Tabulate). By default Cement
adds the ``-o`` command line option to allow the end user to override the
output handler. For example: passing ``-o json`` will override the default
output handler and set it to ``JsonOutputHandler``.
See ``CementApp.Meta.handler_override_options``.
.. code-block:: console
$ python myapp.py -o json
{"foo": "bar"}
What if I Want To Use UltraJson or Something Else?
--------------------------------------------------
It is possible to override the backend ``json`` library module to use, for
example if you wanted to use UltraJson (``ujson``) or another
**drop-in replacement** library. The recommended solution would be to
override the ``JsonOutputHandler`` with you're own sub-classed version, and
modify the ``json_module`` meta-data option.
.. code-block:: python
from cement.ext.ext_json import JsonOutputHandler
class MyJsonHandler(JsonOutputHandler):
class Meta:
json_module = 'ujson'
# then, the class must be replaced via a 'post_setup' hook
def override_json(app):
app.handler.register(MyJsonHandler, force=True)
app.hook.register('post_setup', override_json)
"""
from ..core import output
from ..utils.misc import minimal_logger
from ..ext.ext_configparser import ConfigParserConfigHandler
LOG = minimal_logger(__name__)
def suppress_output_before_run(app):
"""
This is a ``post_argument_parsing`` hook that suppresses console output if
the ``JsonOutputHandler`` is triggered via command line.
:param app: The application object.
"""
if not hasattr(app.pargs, 'output_handler_override'):
return
elif app.pargs.output_handler_override == 'json':
app._suppress_output()
def unsuppress_output_before_render(app, data):
"""
This is a ``pre_render`` that unsuppresses console output if
the ``JsonOutputHandler`` is triggered via command line so that the JSON
is the only thing in the output.
:param app: The application object.
"""
if not hasattr(app.pargs, 'output_handler_override'):
return
elif app.pargs.output_handler_override == 'json':
app._unsuppress_output()
def suppress_output_after_render(app, out_text):
"""
This is a ``post_render`` hook that suppresses console output again after
rendering, only if the ``JsonOutputHandler`` is triggered via command
line.
:param app: The application object.
"""
if not hasattr(app.pargs, 'output_handler_override'):
return
elif app.pargs.output_handler_override == 'json':
app._suppress_output()
class JsonOutputHandler(output.CementOutputHandler):
"""
This class implements the :ref:`IOutput <cement.core.output>`
interface. It provides JSON output from a data dictionary using the
`json <http://docs.python.org/library/json.html>`_ module of the standard
library. Please see the developer documentation on
:ref:`Output Handling <dev_output_handling>`.
This handler forces Cement to suppress console output until
``app.render`` is called (keeping the output pure JSON). If
troubleshooting issues, you will need to pass the ``--debug`` option in
order to unsuppress output and see what's happening.
"""
class Meta:
"""Handler meta-data"""
interface = output.IOutput
"""The interface this class implements."""
label = 'json'
"""The string identifier of this handler."""
#: Whether or not to include ``json`` as an available choice
#: to override the ``output_handler`` via command line options.
overridable = True
#: Backend JSON library module to use (`json`, `ujson`)
json_module = 'json'
def __init__(self, *args, **kw):
super(JsonOutputHandler, self).__init__(*args, **kw)
self._json = None
def _setup(self, app):
super(JsonOutputHandler, self)._setup(app)
self._json = __import__(self._meta.json_module,
globals(), locals(), [], 0)
def render(self, data_dict, template=None, **kw):
"""
Take a data dictionary and render it as Json output. Note that the
template option is received here per the interface, however this
handler just ignores it. Additional keyword arguments passed to
``json.dumps()``.
:param data_dict: The data dictionary to render.
:keyword template: This option is completely ignored.
:returns: A JSON encoded string.
:rtype: ``str``
"""
LOG.debug("rendering output as Json via %s" % self.__module__)
return self._json.dumps(data_dict, **kw)
class JsonConfigHandler(ConfigParserConfigHandler):
"""
This class implements the :ref:`IConfig <cement.core.config>`
interface, and provides the same functionality of
:ref:`ConfigParserConfigHandler <cement.ext.ext_configparser>`
but with JSON configuration files.
"""
class Meta:
"""Handler meta-data."""
label = 'json'
#: Backend JSON library module to use (`json`, `ujson`).
json_module = 'json'
def __init__(self, *args, **kw):
super(JsonConfigHandler, self).__init__(*args, **kw)
self._json = None
def _setup(self, app):
super(JsonConfigHandler, self)._setup(app)
self._json = __import__(self._meta.json_module,
globals(), locals(), [], 0)
def _parse_file(self, file_path):
"""
Parse JSON configuration file settings from file_path, overwriting
existing config settings. If the file does not exist, returns False.
:param file_path: The file system path to the JSON configuration file.
:returns: boolean
"""
self.merge(self._json.load(open(file_path)))
# FIX ME: Should check that file was read properly, however if not it
# will likely raise an exception anyhow.
return True
def load(app):
app.hook.register('post_argument_parsing', suppress_output_before_run)
app.hook.register('pre_render', unsuppress_output_before_render)
app.hook.register('post_render', suppress_output_after_render)
app.handler.register(JsonOutputHandler)
app.handler.register(JsonConfigHandler)
|