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import six
import json
import copy
import warnings
from collections import MutableMapping
from importlib import import_module
from pprint import pformat
from scrapy.utils.deprecate import create_deprecated_class
from scrapy.exceptions import ScrapyDeprecationWarning
from . import default_settings
SETTINGS_PRIORITIES = {
'default': 0,
'command': 10,
'project': 20,
'spider': 30,
'cmdline': 40,
}
def get_settings_priority(priority):
"""
Small helper function that looks up a given string priority in the
:attr:`~scrapy.settings.SETTINGS_PRIORITIES` dictionary and returns its
numerical value, or directly returns a given numerical priority.
"""
if isinstance(priority, six.string_types):
return SETTINGS_PRIORITIES[priority]
else:
return priority
class SettingsAttribute(object):
"""Class for storing data related to settings attributes.
This class is intended for internal usage, you should try Settings class
for settings configuration, not this one.
"""
def __init__(self, value, priority):
self.value = value
if isinstance(self.value, BaseSettings):
self.priority = max(self.value.maxpriority(), priority)
else:
self.priority = priority
def set(self, value, priority):
"""Sets value if priority is higher or equal than current priority."""
if priority >= self.priority:
if isinstance(self.value, BaseSettings):
value = BaseSettings(value, priority=priority)
self.value = value
self.priority = priority
def __str__(self):
return "<SettingsAttribute value={self.value!r} " \
"priority={self.priority}>".format(self=self)
__repr__ = __str__
class BaseSettings(MutableMapping):
"""
Instances of this class behave like dictionaries, but store priorities
along with their ``(key, value)`` pairs, and can be frozen (i.e. marked
immutable).
Key-value entries can be passed on initialization with the ``values``
argument, and they would take the ``priority`` level (unless ``values`` is
already an instance of :class:`~scrapy.settings.BaseSettings`, in which
case the existing priority levels will be kept). If the ``priority``
argument is a string, the priority name will be looked up in
:attr:`~scrapy.settings.SETTINGS_PRIORITIES`. Otherwise, a specific integer
should be provided.
Once the object is created, new settings can be loaded or updated with the
:meth:`~scrapy.settings.BaseSettings.set` method, and can be accessed with
the square bracket notation of dictionaries, or with the
:meth:`~scrapy.settings.BaseSettings.get` method of the instance and its
value conversion variants. When requesting a stored key, the value with the
highest priority will be retrieved.
"""
def __init__(self, values=None, priority='project'):
self.frozen = False
self.attributes = {}
self.update(values, priority)
def __getitem__(self, opt_name):
if opt_name not in self:
return None
return self.attributes[opt_name].value
def __contains__(self, name):
return name in self.attributes
def get(self, name, default=None):
"""
Get a setting value without affecting its original type.
:param name: the setting name
:type name: string
:param default: the value to return if no setting is found
:type default: any
"""
return self[name] if self[name] is not None else default
def getbool(self, name, default=False):
"""
Get a setting value as a boolean.
``1``, ``'1'``, and ``True`` return ``True``, while ``0``, ``'0'``,
``False`` and ``None`` return ``False``.
For example, settings populated through environment variables set to
``'0'`` will return ``False`` when using this method.
:param name: the setting name
:type name: string
:param default: the value to return if no setting is found
:type default: any
"""
return bool(int(self.get(name, default)))
def getint(self, name, default=0):
"""
Get a setting value as an int.
:param name: the setting name
:type name: string
:param default: the value to return if no setting is found
:type default: any
"""
return int(self.get(name, default))
def getfloat(self, name, default=0.0):
"""
Get a setting value as a float.
:param name: the setting name
:type name: string
:param default: the value to return if no setting is found
:type default: any
"""
return float(self.get(name, default))
def getlist(self, name, default=None):
"""
Get a setting value as a list. If the setting original type is a list, a
copy of it will be returned. If it's a string it will be split by ",".
For example, settings populated through environment variables set to
``'one,two'`` will return a list ['one', 'two'] when using this method.
:param name: the setting name
:type name: string
:param default: the value to return if no setting is found
:type default: any
"""
value = self.get(name, default or [])
if isinstance(value, six.string_types):
value = value.split(',')
return list(value)
def getdict(self, name, default=None):
"""
Get a setting value as a dictionary. If the setting original type is a
dictionary, a copy of it will be returned. If it is a string it will be
evaluated as a JSON dictionary. In the case that it is a
:class:`~scrapy.settings.BaseSettings` instance itself, it will be
converted to a dictionary, containing all its current settings values
as they would be returned by :meth:`~scrapy.settings.BaseSettings.get`,
and losing all information about priority and mutability.
:param name: the setting name
:type name: string
:param default: the value to return if no setting is found
:type default: any
"""
value = self.get(name, default or {})
if isinstance(value, six.string_types):
value = json.loads(value)
return dict(value)
def getwithbase(self, name):
"""Get a composition of a dictionary-like setting and its `_BASE`
counterpart.
:param name: name of the dictionary-like setting
:type name: string
"""
compbs = BaseSettings()
compbs.update(self[name + '_BASE'])
compbs.update(self[name])
return compbs
def getpriority(self, name):
"""
Return the current numerical priority value of a setting, or ``None`` if
the given ``name`` does not exist.
:param name: the setting name
:type name: string
"""
if name not in self:
return None
return self.attributes[name].priority
def maxpriority(self):
"""
Return the numerical value of the highest priority present throughout
all settings, or the numerical value for ``default`` from
:attr:`~scrapy.settings.SETTINGS_PRIORITIES` if there are no settings
stored.
"""
if len(self) > 0:
return max(self.getpriority(name) for name in self)
else:
return get_settings_priority('default')
def __setitem__(self, name, value):
self.set(name, value)
def set(self, name, value, priority='project'):
"""
Store a key/value attribute with a given priority.
Settings should be populated *before* configuring the Crawler object
(through the :meth:`~scrapy.crawler.Crawler.configure` method),
otherwise they won't have any effect.
:param name: the setting name
:type name: string
:param value: the value to associate with the setting
:type value: any
:param priority: the priority of the setting. Should be a key of
:attr:`~scrapy.settings.SETTINGS_PRIORITIES` or an integer
:type priority: string or int
"""
self._assert_mutability()
priority = get_settings_priority(priority)
if name not in self:
if isinstance(value, SettingsAttribute):
self.attributes[name] = value
else:
self.attributes[name] = SettingsAttribute(value, priority)
else:
self.attributes[name].set(value, priority)
def setdict(self, values, priority='project'):
self.update(values, priority)
def setmodule(self, module, priority='project'):
"""
Store settings from a module with a given priority.
This is a helper function that calls
:meth:`~scrapy.settings.BaseSettings.set` for every globally declared
uppercase variable of ``module`` with the provided ``priority``.
:param module: the module or the path of the module
:type module: module object or string
:param priority: the priority of the settings. Should be a key of
:attr:`~scrapy.settings.SETTINGS_PRIORITIES` or an integer
:type priority: string or int
"""
self._assert_mutability()
if isinstance(module, six.string_types):
module = import_module(module)
for key in dir(module):
if key.isupper():
self.set(key, getattr(module, key), priority)
def update(self, values, priority='project'):
"""
Store key/value pairs with a given priority.
This is a helper function that calls
:meth:`~scrapy.settings.BaseSettings.set` for every item of ``values``
with the provided ``priority``.
If ``values`` is a string, it is assumed to be JSON-encoded and parsed
into a dict with ``json.loads()`` first. If it is a
:class:`~scrapy.settings.BaseSettings` instance, the per-key priorities
will be used and the ``priority`` parameter ignored. This allows
inserting/updating settings with different priorities with a single
command.
:param values: the settings names and values
:type values: dict or string or :class:`~scrapy.settings.BaseSettings`
:param priority: the priority of the settings. Should be a key of
:attr:`~scrapy.settings.SETTINGS_PRIORITIES` or an integer
:type priority: string or int
"""
self._assert_mutability()
if isinstance(values, six.string_types):
values = json.loads(values)
if values is not None:
if isinstance(values, BaseSettings):
for name, value in six.iteritems(values):
self.set(name, value, values.getpriority(name))
else:
for name, value in six.iteritems(values):
self.set(name, value, priority)
def delete(self, name, priority='project'):
self._assert_mutability()
priority = get_settings_priority(priority)
if priority >= self.getpriority(name):
del self.attributes[name]
def __delitem__(self, name):
self._assert_mutability()
del self.attributes[name]
def _assert_mutability(self):
if self.frozen:
raise TypeError("Trying to modify an immutable Settings object")
def copy(self):
"""
Make a deep copy of current settings.
This method returns a new instance of the :class:`Settings` class,
populated with the same values and their priorities.
Modifications to the new object won't be reflected on the original
settings.
"""
return copy.deepcopy(self)
def freeze(self):
"""
Disable further changes to the current settings.
After calling this method, the present state of the settings will become
immutable. Trying to change values through the :meth:`~set` method and
its variants won't be possible and will be alerted.
"""
self.frozen = True
def frozencopy(self):
"""
Return an immutable copy of the current settings.
Alias for a :meth:`~freeze` call in the object returned by :meth:`copy`.
"""
copy = self.copy()
copy.freeze()
return copy
def __iter__(self):
return iter(self.attributes)
def __len__(self):
return len(self.attributes)
def _to_dict(self):
return {k: (v._to_dict() if isinstance(v, BaseSettings) else v)
for k, v in six.iteritems(self)}
def copy_to_dict(self):
"""
Make a copy of current settings and convert to a dict.
This method returns a new dict populated with the same values
and their priorities as the current settings.
Modifications to the returned dict won't be reflected on the original
settings.
This method can be useful for example for printing settings
in Scrapy shell.
"""
settings = self.copy()
return settings._to_dict()
def _repr_pretty_(self, p, cycle):
if cycle:
p.text(repr(self))
else:
p.text(pformat(self.copy_to_dict()))
@property
def overrides(self):
warnings.warn("`Settings.overrides` attribute is deprecated and won't "
"be supported in Scrapy 0.26, use "
"`Settings.set(name, value, priority='cmdline')` instead",
category=ScrapyDeprecationWarning, stacklevel=2)
try:
o = self._overrides
except AttributeError:
self._overrides = o = _DictProxy(self, 'cmdline')
return o
@property
def defaults(self):
warnings.warn("`Settings.defaults` attribute is deprecated and won't "
"be supported in Scrapy 0.26, use "
"`Settings.set(name, value, priority='default')` instead",
category=ScrapyDeprecationWarning, stacklevel=2)
try:
o = self._defaults
except AttributeError:
self._defaults = o = _DictProxy(self, 'default')
return o
class _DictProxy(MutableMapping):
def __init__(self, settings, priority):
self.o = {}
self.settings = settings
self.priority = priority
def __len__(self):
return len(self.o)
def __getitem__(self, k):
return self.o[k]
def __setitem__(self, k, v):
self.settings.set(k, v, priority=self.priority)
self.o[k] = v
def __delitem__(self, k):
del self.o[k]
def __iter__(self, k, v):
return iter(self.o)
class Settings(BaseSettings):
"""
This object stores Scrapy settings for the configuration of internal
components, and can be used for any further customization.
It is a direct subclass and supports all methods of
:class:`~scrapy.settings.BaseSettings`. Additionally, after instantiation
of this class, the new object will have the global default settings
described on :ref:`topics-settings-ref` already populated.
"""
def __init__(self, values=None, priority='project'):
# Do not pass kwarg values here. We don't want to promote user-defined
# dicts, and we want to update, not replace, default dicts with the
# values given by the user
super(Settings, self).__init__()
self.setmodule(default_settings, 'default')
# Promote default dictionaries to BaseSettings instances for per-key
# priorities
for name, val in six.iteritems(self):
if isinstance(val, dict):
self.set(name, BaseSettings(val, 'default'), 'default')
self.update(values, priority)
class CrawlerSettings(Settings):
def __init__(self, settings_module=None, **kw):
self.settings_module = settings_module
Settings.__init__(self, **kw)
def __getitem__(self, opt_name):
if opt_name in self.overrides:
return self.overrides[opt_name]
if self.settings_module and hasattr(self.settings_module, opt_name):
return getattr(self.settings_module, opt_name)
if opt_name in self.defaults:
return self.defaults[opt_name]
return Settings.__getitem__(self, opt_name)
def __str__(self):
return "<CrawlerSettings module=%r>" % self.settings_module
CrawlerSettings = create_deprecated_class(
'CrawlerSettings', CrawlerSettings,
new_class_path='scrapy.settings.Settings')
def iter_default_settings():
"""Return the default settings as an iterator of (name, value) tuples"""
for name in dir(default_settings):
if name.isupper():
yield name, getattr(default_settings, name)
def overridden_settings(settings):
"""Return a dict of the settings that have been overridden"""
for name, defvalue in iter_default_settings():
value = settings[name]
if not isinstance(defvalue, dict) and value != defvalue:
yield name, value