197 lines
7.4 KiB
Python
197 lines
7.4 KiB
Python
from django.core.exceptions import ImproperlyConfigured
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from django.utils import lru_cache, six
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from django.utils.functional import cached_property
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from django.utils.module_loading import import_string
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from .base import Context, Template
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from .context import _builtin_context_processors
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from .exceptions import TemplateDoesNotExist
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from .library import import_library
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class Engine(object):
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default_builtins = [
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'django.template.defaulttags',
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'django.template.defaultfilters',
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'django.template.loader_tags',
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]
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def __init__(self, dirs=None, app_dirs=False, context_processors=None,
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debug=False, loaders=None, string_if_invalid='',
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file_charset='utf-8', libraries=None, builtins=None):
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if dirs is None:
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dirs = []
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if context_processors is None:
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context_processors = []
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if loaders is None:
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loaders = ['django.template.loaders.filesystem.Loader']
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if app_dirs:
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loaders += ['django.template.loaders.app_directories.Loader']
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else:
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if app_dirs:
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raise ImproperlyConfigured(
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"app_dirs must not be set when loaders is defined.")
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if libraries is None:
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libraries = {}
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if builtins is None:
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builtins = []
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self.dirs = dirs
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self.app_dirs = app_dirs
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self.context_processors = context_processors
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self.debug = debug
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self.loaders = loaders
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self.string_if_invalid = string_if_invalid
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self.file_charset = file_charset
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self.libraries = libraries
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self.template_libraries = self.get_template_libraries(libraries)
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self.builtins = self.default_builtins + builtins
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self.template_builtins = self.get_template_builtins(self.builtins)
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@staticmethod
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@lru_cache.lru_cache()
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def get_default():
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"""
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When only one DjangoTemplates backend is configured, returns it.
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Raises ImproperlyConfigured otherwise.
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This is required for preserving historical APIs that rely on a
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globally available, implicitly configured engine such as:
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>>> from django.template import Context, Template
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>>> template = Template("Hello {{ name }}!")
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>>> context = Context({'name': "world"})
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>>> template.render(context)
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'Hello world!'
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"""
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# Since Engine is imported in django.template and since
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# DjangoTemplates is a wrapper around this Engine class,
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# local imports are required to avoid import loops.
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from django.template import engines
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from django.template.backends.django import DjangoTemplates
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django_engines = [engine for engine in engines.all()
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if isinstance(engine, DjangoTemplates)]
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if len(django_engines) == 1:
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# Unwrap the Engine instance inside DjangoTemplates
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return django_engines[0].engine
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elif len(django_engines) == 0:
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raise ImproperlyConfigured(
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"No DjangoTemplates backend is configured.")
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else:
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raise ImproperlyConfigured(
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"Several DjangoTemplates backends are configured. "
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"You must select one explicitly.")
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@cached_property
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def template_context_processors(self):
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context_processors = _builtin_context_processors
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context_processors += tuple(self.context_processors)
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return tuple(import_string(path) for path in context_processors)
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def get_template_builtins(self, builtins):
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return [import_library(x) for x in builtins]
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def get_template_libraries(self, libraries):
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loaded = {}
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for name, path in libraries.items():
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loaded[name] = import_library(path)
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return loaded
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@cached_property
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def template_loaders(self):
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return self.get_template_loaders(self.loaders)
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def get_template_loaders(self, template_loaders):
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loaders = []
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for template_loader in template_loaders:
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loader = self.find_template_loader(template_loader)
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if loader is not None:
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loaders.append(loader)
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return loaders
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def find_template_loader(self, loader):
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if isinstance(loader, (tuple, list)):
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args = list(loader[1:])
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loader = loader[0]
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else:
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args = []
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if isinstance(loader, six.string_types):
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loader_class = import_string(loader)
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return loader_class(self, *args)
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else:
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raise ImproperlyConfigured(
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"Invalid value in template loaders configuration: %r" % loader)
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def find_template(self, name, dirs=None, skip=None):
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tried = []
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for loader in self.template_loaders:
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if loader.supports_recursion:
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try:
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template = loader.get_template(
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name, template_dirs=dirs, skip=skip,
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)
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return template, template.origin
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except TemplateDoesNotExist as e:
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tried.extend(e.tried)
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else:
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# RemovedInDjango20Warning: Use old api for non-recursive
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# loaders.
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try:
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return loader(name, dirs)
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except TemplateDoesNotExist:
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pass
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raise TemplateDoesNotExist(name, tried=tried)
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def from_string(self, template_code):
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"""
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Returns a compiled Template object for the given template code,
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handling template inheritance recursively.
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"""
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return Template(template_code, engine=self)
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def get_template(self, template_name):
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"""
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Returns a compiled Template object for the given template name,
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handling template inheritance recursively.
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"""
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template, origin = self.find_template(template_name)
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if not hasattr(template, 'render'):
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# template needs to be compiled
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template = Template(template, origin, template_name, engine=self)
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return template
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def render_to_string(self, template_name, context=None):
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"""
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Render the template specified by template_name with the given context.
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For use in Django's test suite.
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"""
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if isinstance(template_name, (list, tuple)):
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t = self.select_template(template_name)
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else:
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t = self.get_template(template_name)
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# Django < 1.8 accepted a Context in `context` even though that's
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# unintended. Preserve this ability but don't rewrap `context`.
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if isinstance(context, Context):
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return t.render(context)
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else:
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return t.render(Context(context))
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def select_template(self, template_name_list):
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"""
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Given a list of template names, returns the first that can be loaded.
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"""
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if not template_name_list:
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raise TemplateDoesNotExist("No template names provided")
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not_found = []
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for template_name in template_name_list:
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try:
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return self.get_template(template_name)
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except TemplateDoesNotExist as exc:
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if exc.args[0] not in not_found:
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not_found.append(exc.args[0])
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continue
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# If we get here, none of the templates could be loaded
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raise TemplateDoesNotExist(', '.join(not_found))
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