90 lines
3.5 KiB
Python
90 lines
3.5 KiB
Python
"""
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Wrapper class that takes a list of template loaders as an argument and attempts
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to load templates from them in order, caching the result.
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"""
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import hashlib
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from django.template.base import TemplateDoesNotExist
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from django.template.loader import get_template_from_string, find_template_loader, make_origin
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from django.utils.encoding import force_bytes
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from .base import Loader as BaseLoader
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class Loader(BaseLoader):
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is_usable = True
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def __init__(self, loaders):
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self.template_cache = {}
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self.find_template_cache = {}
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self._loaders = loaders
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self._cached_loaders = []
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@property
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def loaders(self):
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# Resolve loaders on demand to avoid circular imports
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if not self._cached_loaders:
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# Set self._cached_loaders atomically. Otherwise, another thread
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# could see an incomplete list. See #17303.
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cached_loaders = []
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for loader in self._loaders:
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cached_loaders.append(find_template_loader(loader))
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self._cached_loaders = cached_loaders
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return self._cached_loaders
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def cache_key(self, template_name, template_dirs):
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if template_dirs:
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# If template directories were specified, use a hash to differentiate
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return '-'.join([template_name, hashlib.sha1(force_bytes('|'.join(template_dirs))).hexdigest()])
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else:
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return template_name
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def find_template(self, name, dirs=None):
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"""
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Helper method. Lookup the template :param name: in all the configured loaders
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"""
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key = self.cache_key(name, dirs)
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try:
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result = self.find_template_cache[key]
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except KeyError:
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result = None
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for loader in self.loaders:
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try:
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template, display_name = loader(name, dirs)
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except TemplateDoesNotExist:
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pass
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else:
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result = (template, make_origin(display_name, loader, name, dirs))
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break
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self.find_template_cache[key] = result
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if result:
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return result
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else:
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self.template_cache[key] = TemplateDoesNotExist
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raise TemplateDoesNotExist(name)
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def load_template(self, template_name, template_dirs=None):
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key = self.cache_key(template_name, template_dirs)
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template_tuple = self.template_cache.get(key)
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# A cached previous failure:
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if template_tuple is TemplateDoesNotExist:
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raise TemplateDoesNotExist
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elif template_tuple is None:
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template, origin = self.find_template(template_name, template_dirs)
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if not hasattr(template, 'render'):
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try:
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template = get_template_from_string(template, origin, template_name)
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except TemplateDoesNotExist:
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# If compiling the template we found raises TemplateDoesNotExist,
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# back off to returning the source and display name for the template
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# we were asked to load. This allows for correct identification (later)
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# of the actual template that does not exist.
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self.template_cache[key] = (template, origin)
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self.template_cache[key] = (template, None)
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return self.template_cache[key]
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def reset(self):
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"Empty the template cache."
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self.template_cache.clear()
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self.find_template_cache.clear()
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