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# Wrapper for loading templates from storage of some sort (e.g. filesystem, database). |
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# |
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# This uses the TEMPLATE_LOADERS setting, which is a list of loaders to use. |
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# Each loader is expected to have this interface: |
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# |
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# callable(name, dirs=[]) |
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# |
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# name is the template name. |
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# dirs is an optional list of directories to search instead of TEMPLATE_DIRS. |
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# |
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# The loader should return a tuple of (template_source, path). The path returned |
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# might be shown to the user for debugging purposes, so it should identify where |
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# the template was loaded from. |
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# |
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# A loader may return an already-compiled template instead of the actual |
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# template source. In that case the path returned should be None, since the |
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# path information is associated with the template during the compilation, |
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# which has already been done. |
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# |
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# Each loader should have an "is_usable" attribute set. This is a boolean that |
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# specifies whether the loader can be used in this Python installation. Each |
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# loader is responsible for setting this when it's initialized. |
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# |
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# For example, the eggs loader (which is capable of loading templates from |
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# Python eggs) sets is_usable to False if the "pkg_resources" module isn't |
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# installed, because pkg_resources is necessary to read eggs. |
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from django.core.exceptions import ImproperlyConfigured |
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from django.template import Origin, Template, Context, TemplateDoesNotExist, add_to_builtins |
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from django.utils.importlib import import_module |
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from django.conf import settings |
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template_source_loaders = None |
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class BaseLoader(object): |
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is_usable = False |
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def __init__(self, *args, **kwargs): |
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pass |
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def __call__(self, template_name, template_dirs=None): |
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return self.load_template(template_name, template_dirs) |
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def load_template(self, template_name, template_dirs=None): |
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source, display_name = self.load_template_source(template_name, template_dirs) |
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origin = make_origin(display_name, self.load_template_source, template_name, template_dirs) |
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try: |
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template = get_template_from_string(source, origin, template_name) |
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return template, None |
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except TemplateDoesNotExist: |
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# If compiling the template we found raises TemplateDoesNotExist, back off to |
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# returning the source and display name for the template we were asked to load. |
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# This allows for correct identification (later) of the actual template that does |
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# not exist. |
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return source, display_name |
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def load_template_source(self, template_name, template_dirs=None): |
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""" |
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Returns a tuple containing the source and origin for the given template |
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name. |
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""" |
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raise NotImplementedError |
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def reset(self): |
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""" |
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Resets any state maintained by the loader instance (e.g., cached |
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templates or cached loader modules). |
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""" |
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pass |
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class LoaderOrigin(Origin): |
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def __init__(self, display_name, loader, name, dirs): |
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super(LoaderOrigin, self).__init__(display_name) |
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self.loader, self.loadname, self.dirs = loader, name, dirs |
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def reload(self): |
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return self.loader(self.loadname, self.dirs)[0] |
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def make_origin(display_name, loader, name, dirs): |
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if settings.TEMPLATE_DEBUG and display_name: |
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return LoaderOrigin(display_name, loader, name, dirs) |
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else: |
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return None |
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def find_template_loader(loader): |
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if isinstance(loader, (tuple, list)): |
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loader, args = loader[0], loader[1:] |
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else: |
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args = [] |
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if isinstance(loader, basestring): |
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module, attr = loader.rsplit('.', 1) |
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try: |
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mod = import_module(module) |
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except ImportError, e: |
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raise ImproperlyConfigured('Error importing template source loader %s: "%s"' % (loader, e)) |
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try: |
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TemplateLoader = getattr(mod, attr) |
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except AttributeError, e: |
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raise ImproperlyConfigured('Error importing template source loader %s: "%s"' % (loader, e)) |
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if hasattr(TemplateLoader, 'load_template_source'): |
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func = TemplateLoader(*args) |
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else: |
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# Try loading module the old way - string is full path to callable |
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if args: |
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raise ImproperlyConfigured("Error importing template source loader %s - can't pass arguments to function-based loader." % loader) |
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func = TemplateLoader |
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if not func.is_usable: |
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import warnings |
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warnings.warn("Your TEMPLATE_LOADERS setting includes %r, but your Python installation doesn't support that type of template loading. Consider removing that line from TEMPLATE_LOADERS." % loader) |
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return None |
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else: |
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return func |
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else: |
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raise ImproperlyConfigured('Loader does not define a "load_template" callable template source loader') |
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def find_template(name, dirs=None): |
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# Calculate template_source_loaders the first time the function is executed |
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# because putting this logic in the module-level namespace may cause |
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# circular import errors. See Django ticket #1292. |
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global template_source_loaders |
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if template_source_loaders is None: |
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loaders = [] |
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for loader_name in settings.TEMPLATE_LOADERS: |
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loader = find_template_loader(loader_name) |
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if loader is not None: |
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loaders.append(loader) |
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template_source_loaders = tuple(loaders) |
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for loader in template_source_loaders: |
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try: |
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source, display_name = loader(name, dirs) |
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return (source, make_origin(display_name, loader, name, dirs)) |
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except TemplateDoesNotExist: |
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pass |
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raise TemplateDoesNotExist(name) |
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def find_template_source(name, dirs=None): |
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# For backward compatibility |
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import warnings |
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warnings.warn( |
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"`django.template.loaders.find_template_source` is deprecated; use `django.template.loaders.find_template` instead.", |
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PendingDeprecationWarning |
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) |
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template, origin = find_template(name, dirs) |
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if hasattr(template, 'render'): |
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raise Exception("Found a compiled template that is incompatible with the deprecated `django.template.loaders.find_template_source` function.") |
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return template, origin |
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def get_template(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 = 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 = get_template_from_string(template, origin, template_name) |
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return template |
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def get_template_from_string(source, origin=None, name=None): |
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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(source, origin, name) |
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def render_to_string(template_name, dictionary=None, context_instance=None): |
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""" |
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Loads the given template_name and renders it with the given dictionary as |
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context. The template_name may be a string to load a single template using |
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get_template, or it may be a tuple to use select_template to find one of |
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the templates in the list. Returns a string. |
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""" |
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dictionary = dictionary or {} |
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if isinstance(template_name, (list, tuple)): |
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t = select_template(template_name) |
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else: |
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t = get_template(template_name) |
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if context_instance: |
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context_instance.update(dictionary) |
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else: |
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context_instance = Context(dictionary) |
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return t.render(context_instance) |
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def select_template(template_name_list): |
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"Given a list of template names, returns the first that can be loaded." |
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for template_name in template_name_list: |
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try: |
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return get_template(template_name) |
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except TemplateDoesNotExist: |
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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(template_name_list)) |
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add_to_builtins('django.template.loader_tags') |