264 lines
9.7 KiB
Python
264 lines
9.7 KiB
Python
# -*- coding: utf-8 -*-
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"""
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flask.config
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~~~~~~~~~~~~
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Implements the configuration related objects.
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:copyright: (c) 2015 by Armin Ronacher.
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:license: BSD, see LICENSE for more details.
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"""
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import os
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import types
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import errno
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from werkzeug.utils import import_string
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from ._compat import string_types, iteritems
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from . import json
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class ConfigAttribute(object):
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"""Makes an attribute forward to the config"""
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def __init__(self, name, get_converter=None):
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self.__name__ = name
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self.get_converter = get_converter
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def __get__(self, obj, type=None):
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if obj is None:
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return self
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rv = obj.config[self.__name__]
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if self.get_converter is not None:
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rv = self.get_converter(rv)
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return rv
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def __set__(self, obj, value):
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obj.config[self.__name__] = value
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class Config(dict):
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"""Works exactly like a dict but provides ways to fill it from files
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or special dictionaries. There are two common patterns to populate the
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config.
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Either you can fill the config from a config file::
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app.config.from_pyfile('yourconfig.cfg')
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Or alternatively you can define the configuration options in the
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module that calls :meth:`from_object` or provide an import path to
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a module that should be loaded. It is also possible to tell it to
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use the same module and with that provide the configuration values
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just before the call::
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DEBUG = True
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SECRET_KEY = 'development key'
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app.config.from_object(__name__)
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In both cases (loading from any Python file or loading from modules),
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only uppercase keys are added to the config. This makes it possible to use
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lowercase values in the config file for temporary values that are not added
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to the config or to define the config keys in the same file that implements
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the application.
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Probably the most interesting way to load configurations is from an
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environment variable pointing to a file::
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app.config.from_envvar('YOURAPPLICATION_SETTINGS')
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In this case before launching the application you have to set this
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environment variable to the file you want to use. On Linux and OS X
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use the export statement::
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export YOURAPPLICATION_SETTINGS='/path/to/config/file'
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On windows use `set` instead.
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:param root_path: path to which files are read relative from. When the
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config object is created by the application, this is
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the application's :attr:`~flask.Flask.root_path`.
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:param defaults: an optional dictionary of default values
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"""
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def __init__(self, root_path, defaults=None):
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dict.__init__(self, defaults or {})
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self.root_path = root_path
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def from_envvar(self, variable_name, silent=False):
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"""Loads a configuration from an environment variable pointing to
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a configuration file. This is basically just a shortcut with nicer
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error messages for this line of code::
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app.config.from_pyfile(os.environ['YOURAPPLICATION_SETTINGS'])
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:param variable_name: name of the environment variable
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:param silent: set to ``True`` if you want silent failure for missing
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files.
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:return: bool. ``True`` if able to load config, ``False`` otherwise.
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"""
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rv = os.environ.get(variable_name)
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if not rv:
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if silent:
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return False
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raise RuntimeError('The environment variable %r is not set '
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'and as such configuration could not be '
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'loaded. Set this variable and make it '
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'point to a configuration file' %
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variable_name)
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return self.from_pyfile(rv, silent=silent)
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def from_pyfile(self, filename, silent=False):
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"""Updates the values in the config from a Python file. This function
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behaves as if the file was imported as module with the
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:meth:`from_object` function.
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:param filename: the filename of the config. This can either be an
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absolute filename or a filename relative to the
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root path.
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:param silent: set to ``True`` if you want silent failure for missing
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files.
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.. versionadded:: 0.7
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`silent` parameter.
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"""
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filename = os.path.join(self.root_path, filename)
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d = types.ModuleType('config')
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d.__file__ = filename
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try:
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with open(filename, mode='rb') as config_file:
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exec(compile(config_file.read(), filename, 'exec'), d.__dict__)
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except IOError as e:
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if silent and e.errno in (errno.ENOENT, errno.EISDIR):
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return False
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e.strerror = 'Unable to load configuration file (%s)' % e.strerror
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raise
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self.from_object(d)
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return True
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def from_object(self, obj):
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"""Updates the values from the given object. An object can be of one
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of the following two types:
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- a string: in this case the object with that name will be imported
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- an actual object reference: that object is used directly
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Objects are usually either modules or classes. :meth:`from_object`
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loads only the uppercase attributes of the module/class. A ``dict``
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object will not work with :meth:`from_object` because the keys of a
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``dict`` are not attributes of the ``dict`` class.
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Example of module-based configuration::
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app.config.from_object('yourapplication.default_config')
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from yourapplication import default_config
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app.config.from_object(default_config)
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You should not use this function to load the actual configuration but
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rather configuration defaults. The actual config should be loaded
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with :meth:`from_pyfile` and ideally from a location not within the
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package because the package might be installed system wide.
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See :ref:`config-dev-prod` for an example of class-based configuration
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using :meth:`from_object`.
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:param obj: an import name or object
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"""
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if isinstance(obj, string_types):
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obj = import_string(obj)
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for key in dir(obj):
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if key.isupper():
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self[key] = getattr(obj, key)
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def from_json(self, filename, silent=False):
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"""Updates the values in the config from a JSON file. This function
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behaves as if the JSON object was a dictionary and passed to the
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:meth:`from_mapping` function.
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:param filename: the filename of the JSON file. This can either be an
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absolute filename or a filename relative to the
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root path.
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:param silent: set to ``True`` if you want silent failure for missing
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files.
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.. versionadded:: 0.11
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"""
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filename = os.path.join(self.root_path, filename)
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try:
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with open(filename) as json_file:
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obj = json.loads(json_file.read())
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except IOError as e:
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if silent and e.errno in (errno.ENOENT, errno.EISDIR):
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return False
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e.strerror = 'Unable to load configuration file (%s)' % e.strerror
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raise
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return self.from_mapping(obj)
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def from_mapping(self, *mapping, **kwargs):
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"""Updates the config like :meth:`update` ignoring items with non-upper
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keys.
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.. versionadded:: 0.11
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"""
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mappings = []
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if len(mapping) == 1:
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if hasattr(mapping[0], 'items'):
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mappings.append(mapping[0].items())
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else:
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mappings.append(mapping[0])
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elif len(mapping) > 1:
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raise TypeError(
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'expected at most 1 positional argument, got %d' % len(mapping)
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)
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mappings.append(kwargs.items())
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for mapping in mappings:
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for (key, value) in mapping:
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if key.isupper():
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self[key] = value
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return True
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def get_namespace(self, namespace, lowercase=True, trim_namespace=True):
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"""Returns a dictionary containing a subset of configuration options
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that match the specified namespace/prefix. Example usage::
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app.config['IMAGE_STORE_TYPE'] = 'fs'
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app.config['IMAGE_STORE_PATH'] = '/var/app/images'
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app.config['IMAGE_STORE_BASE_URL'] = 'http://img.website.com'
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image_store_config = app.config.get_namespace('IMAGE_STORE_')
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The resulting dictionary `image_store_config` would look like::
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{
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'type': 'fs',
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'path': '/var/app/images',
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'base_url': 'http://img.website.com'
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}
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This is often useful when configuration options map directly to
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keyword arguments in functions or class constructors.
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:param namespace: a configuration namespace
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:param lowercase: a flag indicating if the keys of the resulting
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dictionary should be lowercase
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:param trim_namespace: a flag indicating if the keys of the resulting
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dictionary should not include the namespace
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.. versionadded:: 0.11
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"""
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rv = {}
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for k, v in iteritems(self):
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if not k.startswith(namespace):
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continue
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if trim_namespace:
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key = k[len(namespace):]
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else:
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key = k
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if lowercase:
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key = key.lower()
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rv[key] = v
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return rv
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def __repr__(self):
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return '<%s %s>' % (self.__class__.__name__, dict.__repr__(self))
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