"""
This is the Django template system.
How it works:
The Lexer.tokenize() function converts a template string (i.e., a string containing
markup with custom template tags) to tokens, which can be either plain text
(TOKEN_TEXT), variables (TOKEN_VAR) or block statements (TOKEN_BLOCK).
The Parser() class takes a list of tokens in its constructor, and its parse()
method returns a compiled template -- which is, under the hood, a list of
Node objects.
Each Node is responsible for creating some sort of output -- e.g. simple text
(TextNode), variable values in a given context (VariableNode), results of basic
logic (IfNode), results of looping (ForNode), or anything else. The core Node
types are TextNode, VariableNode, IfNode and ForNode, but plugin modules can
define their own custom node types.
Each Node has a render() method, which takes a Context and returns a string of
the rendered node. For example, the render() method of a Variable Node returns
the variable's value as a string. The render() method of a ForNode returns the
rendered output of whatever was inside the loop, recursively.
The Template class is a convenient wrapper that takes care of template
compilation and rendering.
Usage:
The only thing you should ever use directly in this file is the Template class.
Create a compiled template object with a template_string, then call render()
with a context. In the compilation stage, the TemplateSyntaxError exception
will be raised if the template doesn't have proper syntax.
Sample code:
>>> from django import template
>>> s = u'{% if test %}{{ varvalue }}
{% endif %}'
>>> t = template.Template(s)
(t is now a compiled template, and its render() method can be called multiple
times with multiple contexts)
>>> c = template.Context({'test':True, 'varvalue': 'Hello'})
>>> t.render(c)
u'Hello
'
>>> c = template.Context({'test':False, 'varvalue': 'Hello'})
>>> t.render(c)
u''
"""
from __future__ import unicode_literals
import logging
import re
import warnings
from functools import partial
from importlib import import_module
from inspect import getargspec, getcallargs
from django.apps import apps
from django.template.context import ( # NOQA: imported for backwards compatibility
BaseContext, Context, ContextPopException, RequestContext,
)
from django.utils import lru_cache, six
from django.utils.deprecation import (
RemovedInDjango20Warning, RemovedInDjango21Warning,
)
from django.utils.encoding import (
force_str, force_text, python_2_unicode_compatible,
)
from django.utils.formats import localize
from django.utils.html import conditional_escape, escape
from django.utils.itercompat import is_iterable
from django.utils.module_loading import module_has_submodule
from django.utils.safestring import (
EscapeData, SafeData, mark_for_escaping, mark_safe,
)
from django.utils.text import (
get_text_list, smart_split, unescape_string_literal,
)
from django.utils.timezone import template_localtime
from django.utils.translation import pgettext_lazy, ugettext_lazy
TOKEN_TEXT = 0
TOKEN_VAR = 1
TOKEN_BLOCK = 2
TOKEN_COMMENT = 3
TOKEN_MAPPING = {
TOKEN_TEXT: 'Text',
TOKEN_VAR: 'Var',
TOKEN_BLOCK: 'Block',
TOKEN_COMMENT: 'Comment',
}
# template syntax constants
FILTER_SEPARATOR = '|'
FILTER_ARGUMENT_SEPARATOR = ':'
VARIABLE_ATTRIBUTE_SEPARATOR = '.'
BLOCK_TAG_START = '{%'
BLOCK_TAG_END = '%}'
VARIABLE_TAG_START = '{{'
VARIABLE_TAG_END = '}}'
COMMENT_TAG_START = '{#'
COMMENT_TAG_END = '#}'
TRANSLATOR_COMMENT_MARK = 'Translators'
SINGLE_BRACE_START = '{'
SINGLE_BRACE_END = '}'
ALLOWED_VARIABLE_CHARS = ('abcdefghijklmnopqrstuvwxyz'
'ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789_.')
# what to report as the origin for templates that come from non-loader sources
# (e.g. strings)
UNKNOWN_SOURCE = ''
# match a variable or block tag and capture the entire tag, including start/end
# delimiters
tag_re = (re.compile('(%s.*?%s|%s.*?%s|%s.*?%s)' %
(re.escape(BLOCK_TAG_START), re.escape(BLOCK_TAG_END),
re.escape(VARIABLE_TAG_START), re.escape(VARIABLE_TAG_END),
re.escape(COMMENT_TAG_START), re.escape(COMMENT_TAG_END))))
# global dictionary of libraries that have been loaded using get_library
libraries = {}
# global list of libraries to load by default for a new parser
builtins = []
logger = logging.getLogger('django.template')
class TemplateSyntaxError(Exception):
pass
class TemplateDoesNotExist(Exception):
pass
class TemplateEncodingError(Exception):
pass
@python_2_unicode_compatible
class VariableDoesNotExist(Exception):
def __init__(self, msg, params=()):
self.msg = msg
self.params = params
def __str__(self):
return self.msg % tuple(force_text(p, errors='replace') for p in self.params)
class InvalidTemplateLibrary(Exception):
pass
class Origin(object):
def __init__(self, name):
self.name = name
def reload(self):
raise NotImplementedError('subclasses of Origin must provide a reload() method')
def __str__(self):
return self.name
class StringOrigin(Origin):
def __init__(self, source):
super(StringOrigin, self).__init__(UNKNOWN_SOURCE)
self.source = source
def reload(self):
return self.source
class Template(object):
def __init__(self, template_string, origin=None, name=None, engine=None):
try:
template_string = force_text(template_string)
except UnicodeDecodeError:
raise TemplateEncodingError("Templates can only be constructed "
"from unicode or UTF-8 strings.")
# If Template is instantiated directly rather than from an Engine and
# exactly one Django template engine is configured, use that engine.
# This is required to preserve backwards-compatibility for direct use
# e.g. Template('...').render(Context({...}))
if engine is None:
from .engine import Engine
engine = Engine.get_default()
if origin is None:
origin = StringOrigin(template_string)
self.name = name
self.origin = origin
self.engine = engine
self.source = template_string
self.nodelist = self.compile_nodelist()
def __iter__(self):
for node in self.nodelist:
for subnode in node:
yield subnode
def _render(self, context):
return self.nodelist.render(context)
def render(self, context):
"Display stage -- can be called many times"
context.render_context.push()
try:
if context.template is None:
with context.bind_template(self):
context.template_name = self.name
return self._render(context)
else:
return self._render(context)
finally:
context.render_context.pop()
def compile_nodelist(self):
"""
Parse and compile the template source into a nodelist. If debug
is True and an exception occurs during parsing, the exception is
is annotated with contextual line information where it occurred in the
template source.
"""
if self.engine.debug:
lexer = DebugLexer(self.source)
else:
lexer = Lexer(self.source)
tokens = lexer.tokenize()
parser = Parser(tokens)
try:
return parser.parse()
except Exception as e:
if self.engine.debug:
e.template_debug = self.get_exception_info(e, e.token)
raise
def get_exception_info(self, exception, token):
"""
Return a dictionary containing contextual line information of where
the exception occurred in the template. The following information is
provided:
message
The message of the exception raised.
source_lines
The lines before, after, and including the line the exception
occurred on.
line
The line number the exception occurred on.
before, during, after
The line the exception occurred on split into three parts:
1. The content before the token that raised the error.
2. The token that raised the error.
3. The content after the token that raised the error.
total
The number of lines in source_lines.
top
The line number where source_lines starts.
bottom
The line number where source_lines ends.
start
The start position of the token in the template source.
end
The end position of the token in the template source.
"""
start, end = token.position
context_lines = 10
line = 0
upto = 0
source_lines = []
before = during = after = ""
for num, next in enumerate(linebreak_iter(self.source)):
if start >= upto and end <= next:
line = num
before = escape(self.source[upto:start])
during = escape(self.source[start:end])
after = escape(self.source[end:next])
source_lines.append((num, escape(self.source[upto:next])))
upto = next
total = len(source_lines)
top = max(1, line - context_lines)
bottom = min(total, line + 1 + context_lines)
# In some rare cases exc_value.args can be empty or an invalid
# unicode string.
try:
message = force_text(exception.args[0])
except (IndexError, UnicodeDecodeError):
message = '(Could not get exception message)'
return {
'message': message,
'source_lines': source_lines[top:bottom],
'before': before,
'during': during,
'after': after,
'top': top,
'bottom': bottom,
'total': total,
'line': line,
'name': self.origin.name,
'start': start,
'end': end,
}
def linebreak_iter(template_source):
yield 0
p = template_source.find('\n')
while p >= 0:
yield p + 1
p = template_source.find('\n', p + 1)
yield len(template_source) + 1
class Token(object):
def __init__(self, token_type, contents, position=None, lineno=None):
"""
A token representing a string from the template.
token_type
One of TOKEN_TEXT, TOKEN_VAR, TOKEN_BLOCK, or TOKEN_COMMENT.
contents
The token source string.
position
An optional tuple containing the start and end index of the token
in the template source. This is used for traceback information
when debug is on.
lineno
The line number the token appears on in the template source.
This is used for traceback information and gettext files.
"""
self.token_type, self.contents = token_type, contents
self.lineno = lineno
self.position = position
def __str__(self):
token_name = TOKEN_MAPPING[self.token_type]
return ('<%s token: "%s...">' %
(token_name, self.contents[:20].replace('\n', '')))
def split_contents(self):
split = []
bits = iter(smart_split(self.contents))
for bit in bits:
# Handle translation-marked template pieces
if bit.startswith(('_("', "_('")):
sentinal = bit[2] + ')'
trans_bit = [bit]
while not bit.endswith(sentinal):
bit = next(bits)
trans_bit.append(bit)
bit = ' '.join(trans_bit)
split.append(bit)
return split
class Lexer(object):
def __init__(self, template_string):
self.template_string = template_string
self.verbatim = False
def tokenize(self):
"""
Return a list of tokens from a given template_string.
"""
in_tag = False
lineno = 1
result = []
for bit in tag_re.split(self.template_string):
if bit:
result.append(self.create_token(bit, None, lineno, in_tag))
in_tag = not in_tag
lineno += bit.count('\n')
return result
def create_token(self, token_string, position, lineno, in_tag):
"""
Convert the given token string into a new Token object and return it.
If in_tag is True, we are processing something that matched a tag,
otherwise it should be treated as a literal string.
"""
if in_tag and token_string.startswith(BLOCK_TAG_START):
# The [2:-2] ranges below strip off *_TAG_START and *_TAG_END.
# We could do len(BLOCK_TAG_START) to be more "correct", but we've
# hard-coded the 2s here for performance. And it's not like
# the TAG_START values are going to change anytime, anyway.
block_content = token_string[2:-2].strip()
if self.verbatim and block_content == self.verbatim:
self.verbatim = False
if in_tag and not self.verbatim:
if token_string.startswith(VARIABLE_TAG_START):
token = Token(TOKEN_VAR, token_string[2:-2].strip(), position, lineno)
elif token_string.startswith(BLOCK_TAG_START):
if block_content[:9] in ('verbatim', 'verbatim '):
self.verbatim = 'end%s' % block_content
token = Token(TOKEN_BLOCK, block_content, position, lineno)
elif token_string.startswith(COMMENT_TAG_START):
content = ''
if token_string.find(TRANSLATOR_COMMENT_MARK):
content = token_string[2:-2].strip()
token = Token(TOKEN_COMMENT, content, position, lineno)
else:
token = Token(TOKEN_TEXT, token_string, position, lineno)
return token
class DebugLexer(Lexer):
def tokenize(self):
"""
Split a template string into tokens and annotates each token with its
start and end position in the source. This is slower than the default
lexer so we only use it when debug is True.
"""
lineno = 1
result = []
upto = 0
for match in tag_re.finditer(self.template_string):
start, end = match.span()
if start > upto:
token_string = self.template_string[upto:start]
result.append(self.create_token(token_string, (upto, start), lineno, in_tag=False))
lineno += token_string.count('\n')
upto = start
token_string = self.template_string[start:end]
result.append(self.create_token(token_string, (start, end), lineno, in_tag=True))
lineno += token_string.count('\n')
upto = end
last_bit = self.template_string[upto:]
if last_bit:
result.append(self.create_token(last_bit, (upto, upto + len(last_bit)), lineno, in_tag=False))
return result
class Parser(object):
def __init__(self, tokens):
self.tokens = tokens
self.tags = {}
self.filters = {}
self.command_stack = []
for lib in builtins:
self.add_library(lib)
def parse(self, parse_until=None):
"""
Iterate through the parser tokens and compils each one into a node.
If parse_until is provided, parsing will stop once one of the
specified tokens has been reached. This is formatted as a list of
tokens, e.g. ['elif', 'else', 'endif']. If no matching token is
reached, raise an exception with the unclosed block tag details.
"""
if parse_until is None:
parse_until = []
nodelist = NodeList()
while self.tokens:
token = self.next_token()
# Use the raw values here for TOKEN_* for a tiny performance boost.
if token.token_type == 0: # TOKEN_TEXT
self.extend_nodelist(nodelist, TextNode(token.contents), token)
elif token.token_type == 1: # TOKEN_VAR
if not token.contents:
raise self.error(token, 'Empty variable tag')
try:
filter_expression = self.compile_filter(token.contents)
except TemplateSyntaxError as e:
raise self.error(token, e)
var_node = VariableNode(filter_expression)
self.extend_nodelist(nodelist, var_node, token)
elif token.token_type == 2: # TOKEN_BLOCK
try:
command = token.contents.split()[0]
except IndexError:
raise self.error(token, 'Empty block tag')
if command in parse_until:
# A matching token has been reached. Return control to
# the caller. Put the token back on the token list so the
# caller knows where it terminated.
self.prepend_token(token)
return nodelist
# Add the token to the command stack. This is used for error
# messages if further parsing fails due to an unclosed block
# tag.
self.command_stack.append((command, token))
# Get the tag callback function from the ones registered with
# the parser.
try:
compile_func = self.tags[command]
except KeyError:
self.invalid_block_tag(token, command, parse_until)
# Compile the callback into a node object and add it to
# the node list.
try:
compiled_result = compile_func(self, token)
except Exception as e:
raise self.error(token, e)
self.extend_nodelist(nodelist, compiled_result, token)
# Compile success. Remove the token from the command stack.
self.command_stack.pop()
if parse_until:
self.unclosed_block_tag(parse_until)
return nodelist
def skip_past(self, endtag):
while self.tokens:
token = self.next_token()
if token.token_type == TOKEN_BLOCK and token.contents == endtag:
return
self.unclosed_block_tag([endtag])
def extend_nodelist(self, nodelist, node, token):
# Check that non-text nodes don't appear before an extends tag.
if node.must_be_first and nodelist.contains_nontext:
raise self.error(
token, '%r must be the first tag in the template.' % node,
)
if isinstance(nodelist, NodeList) and not isinstance(node, TextNode):
nodelist.contains_nontext = True
# Set token here since we can't modify the node __init__ method
node.token = token
nodelist.append(node)
def error(self, token, e):
"""
Return an exception annotated with the originating token. Since the
parser can be called recursively, check if a token is already set. This
ensures the innermost token is highlighted if an exception occurs,
e.g. a compile error within the body of an if statement.
"""
if not isinstance(e, Exception):
e = TemplateSyntaxError(e)
if not hasattr(e, 'token'):
e.token = token
return e
def invalid_block_tag(self, token, command, parse_until=None):
if parse_until:
raise self.error(token, "Invalid block tag: '%s', expected %s" %
(command, get_text_list(["'%s'" % p for p in parse_until])))
raise self.error(token, "Invalid block tag: '%s'" % command)
def unclosed_block_tag(self, parse_until):
command, token = self.command_stack.pop()
msg = "Unclosed tag '%s'. Looking for one of: %s." % (command, ', '.join(parse_until))
raise self.error(token, msg)
def next_token(self):
return self.tokens.pop(0)
def prepend_token(self, token):
self.tokens.insert(0, token)
def delete_first_token(self):
del self.tokens[0]
def add_library(self, lib):
self.tags.update(lib.tags)
self.filters.update(lib.filters)
def compile_filter(self, token):
"""
Convenient wrapper for FilterExpression
"""
return FilterExpression(token, self)
def find_filter(self, filter_name):
if filter_name in self.filters:
return self.filters[filter_name]
else:
raise TemplateSyntaxError("Invalid filter: '%s'" % filter_name)
# This only matches constant *strings* (things in quotes or marked for
# translation). Numbers are treated as variables for implementation reasons
# (so that they retain their type when passed to filters).
constant_string = r"""
(?:%(i18n_open)s%(strdq)s%(i18n_close)s|
%(i18n_open)s%(strsq)s%(i18n_close)s|
%(strdq)s|
%(strsq)s)
""" % {
'strdq': r'"[^"\\]*(?:\\.[^"\\]*)*"', # double-quoted string
'strsq': r"'[^'\\]*(?:\\.[^'\\]*)*'", # single-quoted string
'i18n_open': re.escape("_("),
'i18n_close': re.escape(")"),
}
constant_string = constant_string.replace("\n", "")
filter_raw_string = r"""
^(?P%(constant)s)|
^(?P[%(var_chars)s]+|%(num)s)|
(?:\s*%(filter_sep)s\s*
(?P\w+)
(?:%(arg_sep)s
(?:
(?P%(constant)s)|
(?P[%(var_chars)s]+|%(num)s)
)
)?
)""" % {
'constant': constant_string,
'num': r'[-+\.]?\d[\d\.e]*',
'var_chars': "\w\.",
'filter_sep': re.escape(FILTER_SEPARATOR),
'arg_sep': re.escape(FILTER_ARGUMENT_SEPARATOR),
}
filter_re = re.compile(filter_raw_string, re.UNICODE | re.VERBOSE)
class FilterExpression(object):
"""
Parses a variable token and its optional filters (all as a single string),
and return a list of tuples of the filter name and arguments.
Sample::
>>> token = 'variable|default:"Default value"|date:"Y-m-d"'
>>> p = Parser('')
>>> fe = FilterExpression(token, p)
>>> len(fe.filters)
2
>>> fe.var
"""
def __init__(self, token, parser):
self.token = token
matches = filter_re.finditer(token)
var_obj = None
filters = []
upto = 0
for match in matches:
start = match.start()
if upto != start:
raise TemplateSyntaxError("Could not parse some characters: "
"%s|%s|%s" %
(token[:upto], token[upto:start],
token[start:]))
if var_obj is None:
var, constant = match.group("var", "constant")
if constant:
try:
var_obj = Variable(constant).resolve({})
except VariableDoesNotExist:
var_obj = None
elif var is None:
raise TemplateSyntaxError("Could not find variable at "
"start of %s." % token)
else:
var_obj = Variable(var)
else:
filter_name = match.group("filter_name")
args = []
constant_arg, var_arg = match.group("constant_arg", "var_arg")
if constant_arg:
args.append((False, Variable(constant_arg).resolve({})))
elif var_arg:
args.append((True, Variable(var_arg)))
filter_func = parser.find_filter(filter_name)
self.args_check(filter_name, filter_func, args)
filters.append((filter_func, args))
upto = match.end()
if upto != len(token):
raise TemplateSyntaxError("Could not parse the remainder: '%s' "
"from '%s'" % (token[upto:], token))
self.filters = filters
self.var = var_obj
def resolve(self, context, ignore_failures=False):
if isinstance(self.var, Variable):
try:
obj = self.var.resolve(context)
except VariableDoesNotExist:
if ignore_failures:
obj = None
else:
string_if_invalid = context.template.engine.string_if_invalid
if string_if_invalid:
if '%s' in string_if_invalid:
return string_if_invalid % self.var
else:
return string_if_invalid
else:
obj = string_if_invalid
else:
obj = self.var
for func, args in self.filters:
arg_vals = []
for lookup, arg in args:
if not lookup:
arg_vals.append(mark_safe(arg))
else:
arg_vals.append(arg.resolve(context))
if getattr(func, 'expects_localtime', False):
obj = template_localtime(obj, context.use_tz)
if getattr(func, 'needs_autoescape', False):
new_obj = func(obj, autoescape=context.autoescape, *arg_vals)
else:
new_obj = func(obj, *arg_vals)
if getattr(func, 'is_safe', False) and isinstance(obj, SafeData):
obj = mark_safe(new_obj)
elif isinstance(obj, EscapeData):
obj = mark_for_escaping(new_obj)
else:
obj = new_obj
return obj
def args_check(name, func, provided):
provided = list(provided)
# First argument, filter input, is implied.
plen = len(provided) + 1
# Check to see if a decorator is providing the real function.
func = getattr(func, '_decorated_function', func)
args, varargs, varkw, defaults = getargspec(func)
alen = len(args)
dlen = len(defaults or [])
# Not enough OR Too many
if plen < (alen - dlen) or plen > alen:
raise TemplateSyntaxError("%s requires %d arguments, %d provided" %
(name, alen - dlen, plen))
return True
args_check = staticmethod(args_check)
def __str__(self):
return self.token
def resolve_variable(path, context):
"""
Returns the resolved variable, which may contain attribute syntax, within
the given context.
Deprecated; use the Variable class instead.
"""
warnings.warn("resolve_variable() is deprecated. Use django.template."
"Variable(path).resolve(context) instead",
RemovedInDjango20Warning, stacklevel=2)
return Variable(path).resolve(context)
class Variable(object):
"""
A template variable, resolvable against a given context. The variable may
be a hard-coded string (if it begins and ends with single or double quote
marks)::
>>> c = {'article': {'section':u'News'}}
>>> Variable('article.section').resolve(c)
u'News'
>>> Variable('article').resolve(c)
{'section': u'News'}
>>> class AClass: pass
>>> c = AClass()
>>> c.article = AClass()
>>> c.article.section = u'News'
(The example assumes VARIABLE_ATTRIBUTE_SEPARATOR is '.')
"""
def __init__(self, var):
self.var = var
self.literal = None
self.lookups = None
self.translate = False
self.message_context = None
if not isinstance(var, six.string_types):
raise TypeError(
"Variable must be a string or number, got %s" % type(var))
try:
# First try to treat this variable as a number.
#
# Note that this could cause an OverflowError here that we're not
# catching. Since this should only happen at compile time, that's
# probably OK.
self.literal = float(var)
# So it's a float... is it an int? If the original value contained a
# dot or an "e" then it was a float, not an int.
if '.' not in var and 'e' not in var.lower():
self.literal = int(self.literal)
# "2." is invalid
if var.endswith('.'):
raise ValueError
except ValueError:
# A ValueError means that the variable isn't a number.
if var.startswith('_(') and var.endswith(')'):
# The result of the lookup should be translated at rendering
# time.
self.translate = True
var = var[2:-1]
# If it's wrapped with quotes (single or double), then
# we're also dealing with a literal.
try:
self.literal = mark_safe(unescape_string_literal(var))
except ValueError:
# Otherwise we'll set self.lookups so that resolve() knows we're
# dealing with a bonafide variable
if var.find(VARIABLE_ATTRIBUTE_SEPARATOR + '_') > -1 or var[0] == '_':
raise TemplateSyntaxError("Variables and attributes may "
"not begin with underscores: '%s'" %
var)
self.lookups = tuple(var.split(VARIABLE_ATTRIBUTE_SEPARATOR))
def resolve(self, context):
"""Resolve this variable against a given context."""
if self.lookups is not None:
# We're dealing with a variable that needs to be resolved
value = self._resolve_lookup(context)
else:
# We're dealing with a literal, so it's already been "resolved"
value = self.literal
if self.translate:
if self.message_context:
return pgettext_lazy(self.message_context, value)
else:
return ugettext_lazy(value)
return value
def __repr__(self):
return "<%s: %r>" % (self.__class__.__name__, self.var)
def __str__(self):
return self.var
def _resolve_lookup(self, context):
"""
Performs resolution of a real variable (i.e. not a literal) against the
given context.
As indicated by the method's name, this method is an implementation
detail and shouldn't be called by external code. Use Variable.resolve()
instead.
"""
current = context
try: # catch-all for silent variable failures
for bit in self.lookups:
try: # dictionary lookup
current = current[bit]
# ValueError/IndexError are for numpy.array lookup on
# numpy < 1.9 and 1.9+ respectively
except (TypeError, AttributeError, KeyError, ValueError, IndexError):
try: # attribute lookup
# Don't return class attributes if the class is the context:
if isinstance(current, BaseContext) and getattr(type(current), bit):
raise AttributeError
current = getattr(current, bit)
except (TypeError, AttributeError) as e:
# Reraise an AttributeError raised by a @property
if (isinstance(e, AttributeError) and
not isinstance(current, BaseContext) and bit in dir(current)):
raise
try: # list-index lookup
current = current[int(bit)]
except (IndexError, # list index out of range
ValueError, # invalid literal for int()
KeyError, # current is a dict without `int(bit)` key
TypeError): # unsubscriptable object
raise VariableDoesNotExist("Failed lookup for key "
"[%s] in %r",
(bit, current)) # missing attribute
if callable(current):
if getattr(current, 'do_not_call_in_templates', False):
pass
elif getattr(current, 'alters_data', False):
current = context.template.engine.string_if_invalid
else:
try: # method call (assuming no args required)
current = current()
except TypeError:
try:
getcallargs(current)
except TypeError: # arguments *were* required
current = context.template.engine.string_if_invalid # invalid method call
else:
raise
except Exception as e:
template_name = getattr(context, 'template_name', 'unknown')
logger.debug('{} - {}'.format(template_name, e))
if getattr(e, 'silent_variable_failure', False):
current = context.template.engine.string_if_invalid
else:
raise
return current
class Node(object):
# Set this to True for nodes that must be first in the template (although
# they can be preceded by text nodes.
must_be_first = False
child_nodelists = ('nodelist',)
token = None
def render(self, context):
"""
Return the node rendered as a string.
"""
pass
def render_annotated(self, context):
"""
Render the node. If debug is True and an exception occurs during
rendering, the exception is annotated with contextual line information
where it occurred in the template. For internal usage this method is
preferred over using the render method directly.
"""
try:
return self.render(context)
except Exception as e:
if context.template.engine.debug and not hasattr(e, 'template_debug'):
e.template_debug = context.template.get_exception_info(e, self.token)
raise
def __iter__(self):
yield self
def get_nodes_by_type(self, nodetype):
"""
Return a list of all nodes (within this node and its nodelist)
of the given type
"""
nodes = []
if isinstance(self, nodetype):
nodes.append(self)
for attr in self.child_nodelists:
nodelist = getattr(self, attr, None)
if nodelist:
nodes.extend(nodelist.get_nodes_by_type(nodetype))
return nodes
class NodeList(list):
# Set to True the first time a non-TextNode is inserted by
# extend_nodelist().
contains_nontext = False
def render(self, context):
bits = []
for node in self:
if isinstance(node, Node):
bit = node.render_annotated(context)
else:
bit = node
bits.append(force_text(bit))
return mark_safe(''.join(bits))
def get_nodes_by_type(self, nodetype):
"Return a list of all nodes of the given type"
nodes = []
for node in self:
nodes.extend(node.get_nodes_by_type(nodetype))
return nodes
class TextNode(Node):
def __init__(self, s):
self.s = s
def __repr__(self):
return force_str("" % self.s[:25], 'ascii',
errors='replace')
def render(self, context):
return self.s
def render_value_in_context(value, context):
"""
Converts any value to a string to become part of a rendered template. This
means escaping, if required, and conversion to a unicode object. If value
is a string, it is expected to have already been translated.
"""
value = template_localtime(value, use_tz=context.use_tz)
value = localize(value, use_l10n=context.use_l10n)
value = force_text(value)
if ((context.autoescape and not isinstance(value, SafeData)) or
isinstance(value, EscapeData)):
return conditional_escape(value)
else:
return value
class VariableNode(Node):
def __init__(self, filter_expression):
self.filter_expression = filter_expression
def __repr__(self):
return "" % self.filter_expression
def render(self, context):
try:
output = self.filter_expression.resolve(context)
except UnicodeDecodeError:
# Unicode conversion can fail sometimes for reasons out of our
# control (e.g. exception rendering). In that case, we fail
# quietly.
return ''
return render_value_in_context(output, context)
# Regex for token keyword arguments
kwarg_re = re.compile(r"(?:(\w+)=)?(.+)")
def token_kwargs(bits, parser, support_legacy=False):
"""
A utility method for parsing token keyword arguments.
:param bits: A list containing remainder of the token (split by spaces)
that is to be checked for arguments. Valid arguments will be removed
from this list.
:param support_legacy: If set to true ``True``, the legacy format
``1 as foo`` will be accepted. Otherwise, only the standard ``foo=1``
format is allowed.
:returns: A dictionary of the arguments retrieved from the ``bits`` token
list.
There is no requirement for all remaining token ``bits`` to be keyword
arguments, so the dictionary will be returned as soon as an invalid
argument format is reached.
"""
if not bits:
return {}
match = kwarg_re.match(bits[0])
kwarg_format = match and match.group(1)
if not kwarg_format:
if not support_legacy:
return {}
if len(bits) < 3 or bits[1] != 'as':
return {}
kwargs = {}
while bits:
if kwarg_format:
match = kwarg_re.match(bits[0])
if not match or not match.group(1):
return kwargs
key, value = match.groups()
del bits[:1]
else:
if len(bits) < 3 or bits[1] != 'as':
return kwargs
key, value = bits[2], bits[0]
del bits[:3]
kwargs[key] = parser.compile_filter(value)
if bits and not kwarg_format:
if bits[0] != 'and':
return kwargs
del bits[:1]
return kwargs
def parse_bits(parser, bits, params, varargs, varkw, defaults,
takes_context, name):
"""
Parses bits for template tag helpers simple_tag and inclusion_tag, in
particular by detecting syntax errors and by extracting positional and
keyword arguments.
"""
if takes_context:
if params[0] == 'context':
params = params[1:]
else:
raise TemplateSyntaxError(
"'%s' is decorated with takes_context=True so it must "
"have a first argument of 'context'" % name)
args = []
kwargs = {}
unhandled_params = list(params)
for bit in bits:
# First we try to extract a potential kwarg from the bit
kwarg = token_kwargs([bit], parser)
if kwarg:
# The kwarg was successfully extracted
param, value = list(six.iteritems(kwarg))[0]
if param not in params and varkw is None:
# An unexpected keyword argument was supplied
raise TemplateSyntaxError(
"'%s' received unexpected keyword argument '%s'" %
(name, param))
elif param in kwargs:
# The keyword argument has already been supplied once
raise TemplateSyntaxError(
"'%s' received multiple values for keyword argument '%s'" %
(name, param))
else:
# All good, record the keyword argument
kwargs[str(param)] = value
if param in unhandled_params:
# If using the keyword syntax for a positional arg, then
# consume it.
unhandled_params.remove(param)
else:
if kwargs:
raise TemplateSyntaxError(
"'%s' received some positional argument(s) after some "
"keyword argument(s)" % name)
else:
# Record the positional argument
args.append(parser.compile_filter(bit))
try:
# Consume from the list of expected positional arguments
unhandled_params.pop(0)
except IndexError:
if varargs is None:
raise TemplateSyntaxError(
"'%s' received too many positional arguments" %
name)
if defaults is not None:
# Consider the last n params handled, where n is the
# number of defaults.
unhandled_params = unhandled_params[:-len(defaults)]
if unhandled_params:
# Some positional arguments were not supplied
raise TemplateSyntaxError(
"'%s' did not receive value(s) for the argument(s): %s" %
(name, ", ".join("'%s'" % p for p in unhandled_params)))
return args, kwargs
def generic_tag_compiler(parser, token, params, varargs, varkw, defaults,
name, takes_context, node_class):
"""
Returns a template.Node subclass.
"""
bits = token.split_contents()[1:]
args, kwargs = parse_bits(parser, bits, params, varargs, varkw,
defaults, takes_context, name)
return node_class(takes_context, args, kwargs)
class TagHelperNode(Node):
"""
Base class for tag helper nodes such as SimpleNode and InclusionNode.
Manages the positional and keyword arguments to be passed to the decorated
function.
"""
def __init__(self, takes_context, args, kwargs):
self.takes_context = takes_context
self.args = args
self.kwargs = kwargs
def get_resolved_arguments(self, context):
resolved_args = [var.resolve(context) for var in self.args]
if self.takes_context:
resolved_args = [context] + resolved_args
resolved_kwargs = {k: v.resolve(context) for k, v in self.kwargs.items()}
return resolved_args, resolved_kwargs
class Library(object):
def __init__(self):
self.filters = {}
self.tags = {}
def tag(self, name=None, compile_function=None):
if name is None and compile_function is None:
# @register.tag()
return self.tag_function
elif name is not None and compile_function is None:
if callable(name):
# @register.tag
return self.tag_function(name)
else:
# @register.tag('somename') or @register.tag(name='somename')
def dec(func):
return self.tag(name, func)
return dec
elif name is not None and compile_function is not None:
# register.tag('somename', somefunc)
self.tags[name] = compile_function
return compile_function
else:
raise InvalidTemplateLibrary("Unsupported arguments to "
"Library.tag: (%r, %r)", (name, compile_function))
def tag_function(self, func):
self.tags[getattr(func, "_decorated_function", func).__name__] = func
return func
def filter(self, name=None, filter_func=None, **flags):
if name is None and filter_func is None:
# @register.filter()
def dec(func):
return self.filter_function(func, **flags)
return dec
elif name is not None and filter_func is None:
if callable(name):
# @register.filter
return self.filter_function(name, **flags)
else:
# @register.filter('somename') or @register.filter(name='somename')
def dec(func):
return self.filter(name, func, **flags)
return dec
elif name is not None and filter_func is not None:
# register.filter('somename', somefunc)
self.filters[name] = filter_func
for attr in ('expects_localtime', 'is_safe', 'needs_autoescape'):
if attr in flags:
value = flags[attr]
# set the flag on the filter for FilterExpression.resolve
setattr(filter_func, attr, value)
# set the flag on the innermost decorated function
# for decorators that need it e.g. stringfilter
if hasattr(filter_func, "_decorated_function"):
setattr(filter_func._decorated_function, attr, value)
filter_func._filter_name = name
return filter_func
else:
raise InvalidTemplateLibrary("Unsupported arguments to "
"Library.filter: (%r, %r)", (name, filter_func))
def filter_function(self, func, **flags):
name = getattr(func, "_decorated_function", func).__name__
return self.filter(name, func, **flags)
def simple_tag(self, func=None, takes_context=None, name=None):
def dec(func):
params, varargs, varkw, defaults = getargspec(func)
class SimpleNode(TagHelperNode):
def __init__(self, takes_context, args, kwargs, target_var):
super(SimpleNode, self).__init__(takes_context, args, kwargs)
self.target_var = target_var
def render(self, context):
resolved_args, resolved_kwargs = self.get_resolved_arguments(context)
output = func(*resolved_args, **resolved_kwargs)
if self.target_var is not None:
context[self.target_var] = output
return ''
return output
function_name = (name or
getattr(func, '_decorated_function', func).__name__)
def compile_func(parser, token):
bits = token.split_contents()[1:]
target_var = None
if len(bits) >= 2 and bits[-2] == 'as':
target_var = bits[-1]
bits = bits[:-2]
args, kwargs = parse_bits(parser, bits, params,
varargs, varkw, defaults, takes_context, function_name)
return SimpleNode(takes_context, args, kwargs, target_var)
compile_func.__doc__ = func.__doc__
self.tag(function_name, compile_func)
return func
if func is None:
# @register.simple_tag(...)
return dec
elif callable(func):
# @register.simple_tag
return dec(func)
else:
raise TemplateSyntaxError("Invalid arguments provided to simple_tag")
def assignment_tag(self, func=None, takes_context=None, name=None):
warnings.warn(
"assignment_tag() is deprecated. Use simple_tag() instead",
RemovedInDjango21Warning,
stacklevel=2,
)
return self.simple_tag(func, takes_context, name)
def inclusion_tag(self, file_name, takes_context=False, name=None):
def dec(func):
params, varargs, varkw, defaults = getargspec(func)
class InclusionNode(TagHelperNode):
def render(self, context):
"""
Renders the specified template and context. Caches the
template object in render_context to avoid reparsing and
loading when used in a for loop.
"""
resolved_args, resolved_kwargs = self.get_resolved_arguments(context)
_dict = func(*resolved_args, **resolved_kwargs)
t = context.render_context.get(self)
if t is None:
if isinstance(file_name, Template):
t = file_name
elif isinstance(getattr(file_name, 'template', None), Template):
t = file_name.template
elif not isinstance(file_name, six.string_types) and is_iterable(file_name):
t = context.template.engine.select_template(file_name)
else:
t = context.template.engine.get_template(file_name)
context.render_context[self] = t
new_context = context.new(_dict)
# Copy across the CSRF token, if present, because
# inclusion tags are often used for forms, and we need
# instructions for using CSRF protection to be as simple
# as possible.
csrf_token = context.get('csrf_token', None)
if csrf_token is not None:
new_context['csrf_token'] = csrf_token
return t.render(new_context)
function_name = (name or
getattr(func, '_decorated_function', func).__name__)
compile_func = partial(generic_tag_compiler,
params=params, varargs=varargs, varkw=varkw,
defaults=defaults, name=function_name,
takes_context=takes_context, node_class=InclusionNode)
compile_func.__doc__ = func.__doc__
self.tag(function_name, compile_func)
return func
return dec
def is_library_missing(name):
"""Check if library that failed to load cannot be found under any
templatetags directory or does exist but fails to import.
Non-existing condition is checked recursively for each subpackage in cases
like /templatetags/subpackage/package/module.py.
"""
# Don't bother to check if '.' is in name since any name will be prefixed
# with some template root.
path, module = name.rsplit('.', 1)
try:
package = import_module(path)
return not module_has_submodule(package, module)
except ImportError:
return is_library_missing(path)
def import_library(taglib_module):
"""
Load a template tag library module.
Verifies that the library contains a 'register' attribute, and
returns that attribute as the representation of the library
"""
try:
mod = import_module(taglib_module)
except ImportError as e:
# If the ImportError is because the taglib submodule does not exist,
# that's not an error that should be raised. If the submodule exists
# and raised an ImportError on the attempt to load it, that we want
# to raise.
if is_library_missing(taglib_module):
return None
else:
raise InvalidTemplateLibrary("ImportError raised loading %s: %s" %
(taglib_module, e))
try:
return mod.register
except AttributeError:
raise InvalidTemplateLibrary("Template library %s does not have "
"a variable named 'register'" %
taglib_module)
@lru_cache.lru_cache()
def get_templatetags_modules():
"""
Return the list of all available template tag modules.
Caches the result for faster access.
"""
templatetags_modules_candidates = ['django.templatetags']
templatetags_modules_candidates.extend(
'%s.templatetags' % app_config.name
for app_config in apps.get_app_configs())
templatetags_modules = []
for templatetag_module in templatetags_modules_candidates:
try:
import_module(templatetag_module)
except ImportError:
continue
else:
templatetags_modules.append(templatetag_module)
return templatetags_modules
def get_library(library_name):
"""
Load the template library module with the given name.
If library is not already loaded loop over all templatetags modules
to locate it.
{% load somelib %} and {% load someotherlib %} loops twice.
Subsequent loads eg. {% load somelib %} in the same process will grab
the cached module from libraries.
"""
lib = libraries.get(library_name, None)
if not lib:
templatetags_modules = get_templatetags_modules()
tried_modules = []
for module in templatetags_modules:
taglib_module = '%s.%s' % (module, library_name)
tried_modules.append(taglib_module)
lib = import_library(taglib_module)
if lib:
libraries[library_name] = lib
break
if not lib:
raise InvalidTemplateLibrary("Template library %s not found, "
"tried %s" %
(library_name,
','.join(tried_modules)))
return lib
def add_to_builtins(module):
builtins.append(import_library(module))
add_to_builtins('django.template.defaulttags')
add_to_builtins('django.template.defaultfilters')
add_to_builtins('django.template.loader_tags')