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"""Default tags used by the template system, available to all templates."""
from __future__ import unicode_literals
import sys
import re
from datetime import datetime
from itertools import groupby, cycle as itertools_cycle
from django.conf import settings
from django.template.base import (Node, NodeList, Template, Context, Library,
TemplateSyntaxError, VariableDoesNotExist, InvalidTemplateLibrary,
BLOCK_TAG_START, BLOCK_TAG_END, VARIABLE_TAG_START, VARIABLE_TAG_END,
SINGLE_BRACE_START, SINGLE_BRACE_END, COMMENT_TAG_START, COMMENT_TAG_END,
VARIABLE_ATTRIBUTE_SEPARATOR, get_library, token_kwargs, kwarg_re)
from django.template.smartif import IfParser, Literal
from django.template.defaultfilters import date
from django.utils.encoding import smart_unicode
from django.utils.safestring import mark_safe
from django.utils.html import format_html
from django.utils import timezone
register = Library()
class AutoEscapeControlNode(Node):
"""Implements the actions of the autoescape tag."""
def __init__(self, setting, nodelist):
self.setting, self.nodelist = setting, nodelist
def render(self, context):
old_setting = context.autoescape
context.autoescape = self.setting
output = self.nodelist.render(context)
context.autoescape = old_setting
if self.setting:
return mark_safe(output)
else:
return output
class CommentNode(Node):
def render(self, context):
return ''
class CsrfTokenNode(Node):
def render(self, context):
csrf_token = context.get('csrf_token', None)
if csrf_token:
if csrf_token == 'NOTPROVIDED':
return format_html("")
else:
return format_html("<div><input type='hidden' name='csrfmiddlewaretoken' value='{0}' /></div>", csrf_token)
else:
# It's very probable that the token is missing because of
# misconfiguration, so we raise a warning
from django.conf import settings
if settings.DEBUG:
import warnings
warnings.warn("A {% csrf_token %} was used in a template, but the context did not provide the value. This is usually caused by not using RequestContext.")
return ''
class CycleNode(Node):
def __init__(self, cyclevars, variable_name=None, silent=False):
self.cyclevars = cyclevars
self.variable_name = variable_name
self.silent = silent
def render(self, context):
if self not in context.render_context:
# First time the node is rendered in template
context.render_context[self] = itertools_cycle(self.cyclevars)
cycle_iter = context.render_context[self]
value = next(cycle_iter).resolve(context)
if self.variable_name:
context[self.variable_name] = value
if self.silent:
return ''
return value
class DebugNode(Node):
def render(self, context):
from pprint import pformat
output = [pformat(val) for val in context]
output.append('\n\n')
output.append(pformat(sys.modules))
return ''.join(output)
class FilterNode(Node):
def __init__(self, filter_expr, nodelist):
self.filter_expr, self.nodelist = filter_expr, nodelist
def render(self, context):
output = self.nodelist.render(context)
# Apply filters.
context.update({'var': output})
filtered = self.filter_expr.resolve(context)
context.pop()
return filtered
class FirstOfNode(Node):
def __init__(self, vars):
self.vars = vars
def render(self, context):
for var in self.vars:
value = var.resolve(context, True)
if value:
return smart_unicode(value)
return ''
class ForNode(Node):
child_nodelists = ('nodelist_loop', 'nodelist_empty')
def __init__(self, loopvars, sequence, is_reversed, nodelist_loop, nodelist_empty=None):
self.loopvars, self.sequence = loopvars, sequence
self.is_reversed = is_reversed
self.nodelist_loop = nodelist_loop
if nodelist_empty is None:
self.nodelist_empty = NodeList()
else:
self.nodelist_empty = nodelist_empty
def __repr__(self):
reversed_text = self.is_reversed and ' reversed' or ''
return "<For Node: for %s in %s, tail_len: %d%s>" % \
(', '.join(self.loopvars), self.sequence, len(self.nodelist_loop),
reversed_text)
def __iter__(self):
for node in self.nodelist_loop:
yield node
for node in self.nodelist_empty:
yield node
def render(self, context):
if 'forloop' in context:
parentloop = context['forloop']
else:
parentloop = {}
context.push()
try:
values = self.sequence.resolve(context, True)
except VariableDoesNotExist:
values = []
if values is None:
values = []
if not hasattr(values, '__len__'):
values = list(values)
len_values = len(values)
if len_values < 1:
context.pop()
return self.nodelist_empty.render(context)
nodelist = NodeList()
if self.is_reversed:
values = reversed(values)
unpack = len(self.loopvars) > 1
# Create a forloop value in the context. We'll update counters on each
# iteration just below.
loop_dict = context['forloop'] = {'parentloop': parentloop}
for i, item in enumerate(values):
# Shortcuts for current loop iteration number.
loop_dict['counter0'] = i
loop_dict['counter'] = i+1
# Reverse counter iteration numbers.
loop_dict['revcounter'] = len_values - i
loop_dict['revcounter0'] = len_values - i - 1
# Boolean values designating first and last times through loop.
loop_dict['first'] = (i == 0)
loop_dict['last'] = (i == len_values - 1)
pop_context = False
if unpack:
# If there are multiple loop variables, unpack the item into
# them.
try:
unpacked_vars = dict(zip(self.loopvars, item))
except TypeError:
pass
else:
pop_context = True
context.update(unpacked_vars)
else:
context[self.loopvars[0]] = item
# In TEMPLATE_DEBUG mode provide source of the node which
# actually raised the exception
if settings.TEMPLATE_DEBUG:
for node in self.nodelist_loop:
try:
nodelist.append(node.render(context))
except Exception as e:
if not hasattr(e, 'django_template_source'):
e.django_template_source = node.source
raise
else:
for node in self.nodelist_loop:
nodelist.append(node.render(context))
if pop_context:
# The loop variables were pushed on to the context so pop them
# off again. This is necessary because the tag lets the length
# of loopvars differ to the length of each set of items and we
# don't want to leave any vars from the previous loop on the
# context.
context.pop()
context.pop()
return nodelist.render(context)
class IfChangedNode(Node):
child_nodelists = ('nodelist_true', 'nodelist_false')
def __init__(self, nodelist_true, nodelist_false, *varlist):
self.nodelist_true, self.nodelist_false = nodelist_true, nodelist_false
self._last_seen = None
self._varlist = varlist
self._id = str(id(self))
def render(self, context):
if 'forloop' in context and self._id not in context['forloop']:
self._last_seen = None
context['forloop'][self._id] = 1
try:
if self._varlist:
# Consider multiple parameters. This automatically behaves
# like an OR evaluation of the multiple variables.
compare_to = [var.resolve(context, True) for var in self._varlist]
else:
compare_to = self.nodelist_true.render(context)
except VariableDoesNotExist:
compare_to = None
if compare_to != self._last_seen:
self._last_seen = compare_to
content = self.nodelist_true.render(context)
return content
elif self.nodelist_false:
return self.nodelist_false.render(context)
return ''
class IfEqualNode(Node):
child_nodelists = ('nodelist_true', 'nodelist_false')
def __init__(self, var1, var2, nodelist_true, nodelist_false, negate):
self.var1, self.var2 = var1, var2
self.nodelist_true, self.nodelist_false = nodelist_true, nodelist_false
self.negate = negate
def __repr__(self):
return "<IfEqualNode>"
def render(self, context):
val1 = self.var1.resolve(context, True)
val2 = self.var2.resolve(context, True)
if (self.negate and val1 != val2) or (not self.negate and val1 == val2):
return self.nodelist_true.render(context)
return self.nodelist_false.render(context)
class IfNode(Node):
def __init__(self, conditions_nodelists):
self.conditions_nodelists = conditions_nodelists
def __repr__(self):
return "<IfNode>"
def __iter__(self):
for _, nodelist in self.conditions_nodelists:
for node in nodelist:
yield node
@property
def nodelist(self):
return NodeList(node for _, nodelist in self.conditions_nodelists for node in nodelist)
def render(self, context):
for condition, nodelist in self.conditions_nodelists:
if condition is not None: # if / elif clause
try:
match = condition.eval(context)
except VariableDoesNotExist:
match = None
else: # else clause
match = True
if match:
return nodelist.render(context)
return ''
class RegroupNode(Node):
def __init__(self, target, expression, var_name):
self.target, self.expression = target, expression
self.var_name = var_name
def resolve_expression(self, obj, context):
# This method is called for each object in self.target. See regroup()
# for the reason why we temporarily put the object in the context.
context[self.var_name] = obj
return self.expression.resolve(context, True)
def render(self, context):
obj_list = self.target.resolve(context, True)
if obj_list == None:
# target variable wasn't found in context; fail silently.
context[self.var_name] = []
return ''
# List of dictionaries in the format:
# {'grouper': 'key', 'list': [list of contents]}.
context[self.var_name] = [
{'grouper': key, 'list': list(val)}
for key, val in
groupby(obj_list, lambda obj: self.resolve_expression(obj, context))
]
return ''
def include_is_allowed(filepath):
for root in settings.ALLOWED_INCLUDE_ROOTS:
if filepath.startswith(root):
return True
return False
class SsiNode(Node):
def __init__(self, filepath, parsed):
self.filepath = filepath
self.parsed = parsed
def render(self, context):
filepath = self.filepath.resolve(context)
if not include_is_allowed(filepath):
if settings.DEBUG:
return "[Didn't have permission to include file]"
else:
return '' # Fail silently for invalid includes.
try:
with open(filepath, 'r') as fp:
output = fp.read()
except IOError:
output = ''
if self.parsed:
try:
t = Template(output, name=filepath)
return t.render(context)
except TemplateSyntaxError as e:
if settings.DEBUG:
return "[Included template had syntax error: %s]" % e
else:
return '' # Fail silently for invalid included templates.
return output
class LoadNode(Node):
def render(self, context):
return ''
class NowNode(Node):
def __init__(self, format_string):
self.format_string = format_string
def render(self, context):
tzinfo = timezone.get_current_timezone() if settings.USE_TZ else None
return date(datetime.now(tz=tzinfo), self.format_string)
class SpacelessNode(Node):
def __init__(self, nodelist):
self.nodelist = nodelist
def render(self, context):
from django.utils.html import strip_spaces_between_tags
return strip_spaces_between_tags(self.nodelist.render(context).strip())
class TemplateTagNode(Node):
mapping = {'openblock': BLOCK_TAG_START,
'closeblock': BLOCK_TAG_END,
'openvariable': VARIABLE_TAG_START,
'closevariable': VARIABLE_TAG_END,
'openbrace': SINGLE_BRACE_START,
'closebrace': SINGLE_BRACE_END,
'opencomment': COMMENT_TAG_START,
'closecomment': COMMENT_TAG_END,
}
def __init__(self, tagtype):
self.tagtype = tagtype
def render(self, context):
return self.mapping.get(self.tagtype, '')
class URLNode(Node):
def __init__(self, view_name, args, kwargs, asvar):
self.view_name = view_name
self.args = args
self.kwargs = kwargs
self.asvar = asvar
def render(self, context):
from django.core.urlresolvers import reverse, NoReverseMatch
args = [arg.resolve(context) for arg in self.args]
kwargs = dict([(smart_unicode(k, 'ascii'), v.resolve(context))
for k, v in self.kwargs.items()])
view_name = self.view_name.resolve(context)
# Try to look up the URL twice: once given the view name, and again
# relative to what we guess is the "main" app. If they both fail,
# re-raise the NoReverseMatch unless we're using the
# {% url ... as var %} construct in which cause return nothing.
url = ''
try:
url = reverse(view_name, args=args, kwargs=kwargs, current_app=context.current_app)
except NoReverseMatch as e:
if settings.SETTINGS_MODULE:
project_name = settings.SETTINGS_MODULE.split('.')[0]
try:
url = reverse(project_name + '.' + view_name,
args=args, kwargs=kwargs,
current_app=context.current_app)
except NoReverseMatch:
if self.asvar is None:
# Re-raise the original exception, not the one with
# the path relative to the project. This makes a
# better error message.
raise e
else:
if self.asvar is None:
raise e
if self.asvar:
context[self.asvar] = url
return ''
else:
return url
class VerbatimNode(Node):
def __init__(self, content):
self.content = content
def render(self, context):
return self.content
class WidthRatioNode(Node):
def __init__(self, val_expr, max_expr, max_width):
self.val_expr = val_expr
self.max_expr = max_expr
self.max_width = max_width
def render(self, context):
try:
value = self.val_expr.resolve(context)
max_value = self.max_expr.resolve(context)
max_width = int(self.max_width.resolve(context))
except VariableDoesNotExist:
return ''
except ValueError:
raise TemplateSyntaxError("widthratio final argument must be an number")
try:
value = float(value)
max_value = float(max_value)
ratio = (value / max_value) * max_width
except ZeroDivisionError:
return '0'
except ValueError:
return ''
return str(int(round(ratio)))
class WithNode(Node):
def __init__(self, var, name, nodelist, extra_context=None):
self.nodelist = nodelist
# var and name are legacy attributes, being left in case they are used
# by third-party subclasses of this Node.
self.extra_context = extra_context or {}
if name:
self.extra_context[name] = var
def __repr__(self):
return "<WithNode>"
def render(self, context):
values = dict([(key, val.resolve(context)) for key, val in
self.extra_context.iteritems()])
context.update(values)
output = self.nodelist.render(context)
context.pop()
return output
@register.tag
def autoescape(parser, token):
"""
Force autoescape behavior for this block.
"""
args = token.contents.split()
if len(args) != 2:
raise TemplateSyntaxError("'autoescape' tag requires exactly one argument.")
arg = args[1]
if arg not in ('on', 'off'):
raise TemplateSyntaxError("'autoescape' argument should be 'on' or 'off'")
nodelist = parser.parse(('endautoescape',))
parser.delete_first_token()
return AutoEscapeControlNode((arg == 'on'), nodelist)
@register.tag
def comment(parser, token):
"""
Ignores everything between ``{% comment %}`` and ``{% endcomment %}``.
"""
parser.skip_past('endcomment')
return CommentNode()
@register.tag
def cycle(parser, token):
"""
Cycles among the given strings each time this tag is encountered.
Within a loop, cycles among the given strings each time through
the loop::
{% for o in some_list %}
<tr class="{% cycle 'row1' 'row2' %}">
...
</tr>
{% endfor %}
Outside of a loop, give the values a unique name the first time you call
it, then use that name each sucessive time through::
<tr class="{% cycle 'row1' 'row2' 'row3' as rowcolors %}">...</tr>
<tr class="{% cycle rowcolors %}">...</tr>
<tr class="{% cycle rowcolors %}">...</tr>
You can use any number of values, separated by spaces. Commas can also
be used to separate values; if a comma is used, the cycle values are
interpreted as literal strings.
The optional flag "silent" can be used to prevent the cycle declaration
from returning any value::
{% cycle 'row1' 'row2' as rowcolors silent %}{# no value here #}
{% for o in some_list %}
<tr class="{% cycle rowcolors %}">{# first value will be "row1" #}
...
</tr>
{% endfor %}
"""
# Note: This returns the exact same node on each {% cycle name %} call;
# that is, the node object returned from {% cycle a b c as name %} and the
# one returned from {% cycle name %} are the exact same object. This
# shouldn't cause problems (heh), but if it does, now you know.
#
# Ugly hack warning: This stuffs the named template dict into parser so
# that names are only unique within each template (as opposed to using
# a global variable, which would make cycle names have to be unique across
# *all* templates.
args = token.split_contents()
if len(args) < 2:
raise TemplateSyntaxError("'cycle' tag requires at least two arguments")
if ',' in args[1]:
# Backwards compatibility: {% cycle a,b %} or {% cycle a,b as foo %}
# case.
args[1:2] = ['"%s"' % arg for arg in args[1].split(",")]
if len(args) == 2:
# {% cycle foo %} case.
name = args[1]
if not hasattr(parser, '_namedCycleNodes'):
raise TemplateSyntaxError("No named cycles in template. '%s' is not defined" % name)
if not name in parser._namedCycleNodes:
raise TemplateSyntaxError("Named cycle '%s' does not exist" % name)
return parser._namedCycleNodes[name]
as_form = False
if len(args) > 4:
# {% cycle ... as foo [silent] %} case.
if args[-3] == "as":
if args[-1] != "silent":
raise TemplateSyntaxError("Only 'silent' flag is allowed after cycle's name, not '%s'." % args[-1])
as_form = True
silent = True
args = args[:-1]
elif args[-2] == "as":
as_form = True
silent = False
if as_form:
name = args[-1]
values = [parser.compile_filter(arg) for arg in args[1:-2]]
node = CycleNode(values, name, silent=silent)
if not hasattr(parser, '_namedCycleNodes'):
parser._namedCycleNodes = {}
parser._namedCycleNodes[name] = node
else:
values = [parser.compile_filter(arg) for arg in args[1:]]
node = CycleNode(values)
return node
@register.tag
def csrf_token(parser, token):
return CsrfTokenNode()
@register.tag
def debug(parser, token):
"""
Outputs a whole load of debugging information, including the current
context and imported modules.
Sample usage::
<pre>
{% debug %}
</pre>
"""
return DebugNode()
@register.tag('filter')
def do_filter(parser, token):
"""
Filters the contents of the block through variable filters.
Filters can also be piped through each other, and they can have
arguments -- just like in variable syntax.
Sample usage::
{% filter force_escape|lower %}
This text will be HTML-escaped, and will appear in lowercase.
{% endfilter %}
Note that the ``escape`` and ``safe`` filters are not acceptable arguments.
Instead, use the ``autoescape`` tag to manage autoescaping for blocks of
template code.
"""
_, rest = token.contents.split(None, 1)
filter_expr = parser.compile_filter("var|%s" % (rest))
for func, unused in filter_expr.filters:
if getattr(func, '_decorated_function', func).__name__ in ('escape', 'safe'):
raise TemplateSyntaxError('"filter %s" is not permitted. Use the "autoescape" tag instead.' % func.__name__)
nodelist = parser.parse(('endfilter',))
parser.delete_first_token()
return FilterNode(filter_expr, nodelist)
@register.tag
def firstof(parser, token):
"""
Outputs the first variable passed that is not False, without escaping.
Outputs nothing if all the passed variables are False.
Sample usage::
{% firstof var1 var2 var3 %}
This is equivalent to::
{% if var1 %}
{{ var1|safe }}
{% else %}{% if var2 %}
{{ var2|safe }}
{% else %}{% if var3 %}
{{ var3|safe }}
{% endif %}{% endif %}{% endif %}
but obviously much cleaner!
You can also use a literal string as a fallback value in case all
passed variables are False::
{% firstof var1 var2 var3 "fallback value" %}
If you want to escape the output, use a filter tag::
{% filter force_escape %}
{% firstof var1 var2 var3 "fallback value" %}
{% endfilter %}
"""
bits = token.split_contents()[1:]
if len(bits) < 1:
raise TemplateSyntaxError("'firstof' statement requires at least one argument")
return FirstOfNode([parser.compile_filter(bit) for bit in bits])
@register.tag('for')
def do_for(parser, token):
"""
Loops over each item in an array.
For example, to display a list of athletes given ``athlete_list``::
<ul>
{% for athlete in athlete_list %}
<li>{{ athlete.name }}</li>
{% endfor %}
</ul>
You can loop over a list in reverse by using
``{% for obj in list reversed %}``.
You can also unpack multiple values from a two-dimensional array::
{% for key,value in dict.items %}
{{ key }}: {{ value }}
{% endfor %}
The ``for`` tag can take an optional ``{% empty %}`` clause that will
be displayed if the given array is empty or could not be found::
<ul>
{% for athlete in athlete_list %}
<li>{{ athlete.name }}</li>
{% empty %}
<li>Sorry, no athletes in this list.</li>
{% endfor %}
<ul>
The above is equivalent to -- but shorter, cleaner, and possibly faster
than -- the following::
<ul>
{% if althete_list %}
{% for athlete in athlete_list %}
<li>{{ athlete.name }}</li>
{% endfor %}
{% else %}
<li>Sorry, no athletes in this list.</li>
{% endif %}
</ul>
The for loop sets a number of variables available within the loop:
========================== ================================================
Variable Description
========================== ================================================
``forloop.counter`` The current iteration of the loop (1-indexed)
``forloop.counter0`` The current iteration of the loop (0-indexed)
``forloop.revcounter`` The number of iterations from the end of the
loop (1-indexed)
``forloop.revcounter0`` The number of iterations from the end of the
loop (0-indexed)
``forloop.first`` True if this is the first time through the loop
``forloop.last`` True if this is the last time through the loop
``forloop.parentloop`` For nested loops, this is the loop "above" the
current one
========================== ================================================
"""
bits = token.contents.split()
if len(bits) < 4:
raise TemplateSyntaxError("'for' statements should have at least four"
" words: %s" % token.contents)
is_reversed = bits[-1] == 'reversed'
in_index = is_reversed and -3 or -2
if bits[in_index] != 'in':
raise TemplateSyntaxError("'for' statements should use the format"
" 'for x in y': %s" % token.contents)
loopvars = re.split(r' *, *', ' '.join(bits[1:in_index]))
for var in loopvars:
if not var or ' ' in var:
raise TemplateSyntaxError("'for' tag received an invalid argument:"
" %s" % token.contents)
sequence = parser.compile_filter(bits[in_index+1])
nodelist_loop = parser.parse(('empty', 'endfor',))
token = parser.next_token()
if token.contents == 'empty':
nodelist_empty = parser.parse(('endfor',))
parser.delete_first_token()
else:
nodelist_empty = None
return ForNode(loopvars, sequence, is_reversed, nodelist_loop, nodelist_empty)
def do_ifequal(parser, token, negate):
bits = list(token.split_contents())
if len(bits) != 3:
raise TemplateSyntaxError("%r takes two arguments" % bits[0])
end_tag = 'end' + bits[0]
nodelist_true = parser.parse(('else', end_tag))
token = parser.next_token()
if token.contents == 'else':
nodelist_false = parser.parse((end_tag,))
parser.delete_first_token()
else:
nodelist_false = NodeList()
val1 = parser.compile_filter(bits[1])
val2 = parser.compile_filter(bits[2])
return IfEqualNode(val1, val2, nodelist_true, nodelist_false, negate)
@register.tag
def ifequal(parser, token):
"""
Outputs the contents of the block if the two arguments equal each other.
Examples::
{% ifequal user.id comment.user_id %}
...
{% endifequal %}
{% ifnotequal user.id comment.user_id %}
...
{% else %}
...
{% endifnotequal %}
"""
return do_ifequal(parser, token, False)
@register.tag
def ifnotequal(parser, token):
"""
Outputs the contents of the block if the two arguments are not equal.
See ifequal.
"""
return do_ifequal(parser, token, True)
class TemplateLiteral(Literal):
def __init__(self, value, text):
self.value = value
self.text = text # for better error messages
def display(self):
return self.text
def eval(self, context):
return self.value.resolve(context, ignore_failures=True)
class TemplateIfParser(IfParser):
error_class = TemplateSyntaxError
def __init__(self, parser, *args, **kwargs):
self.template_parser = parser
super(TemplateIfParser, self).__init__(*args, **kwargs)
def create_var(self, value):
return TemplateLiteral(self.template_parser.compile_filter(value), value)
@register.tag('if')
def do_if(parser, token):
"""
The ``{% if %}`` tag evaluates a variable, and if that variable is "true"
(i.e., exists, is not empty, and is not a false boolean value), the
contents of the block are output:
::
{% if athlete_list %}
Number of athletes: {{ athlete_list|count }}
{% elif athlete_in_locker_room_list %}
Athletes should be out of the locker room soon!
{% else %}
No athletes.
{% endif %}
In the above, if ``athlete_list`` is not empty, the number of athletes will
be displayed by the ``{{ athlete_list|count }}`` variable.
As you can see, the ``if`` tag may take one or several `` {% elif %}``
clauses, as well as an ``{% else %}`` clause that will be displayed if all
previous conditions fail. These clauses are optional.
``if`` tags may use ``or``, ``and`` or ``not`` to test a number of
variables or to negate a given variable::
{% if not athlete_list %}
There are no athletes.
{% endif %}
{% if athlete_list or coach_list %}
There are some athletes or some coaches.
{% endif %}
{% if athlete_list and coach_list %}
Both atheletes and coaches are available.
{% endif %}
{% if not athlete_list or coach_list %}
There are no athletes, or there are some coaches.
{% endif %}
{% if athlete_list and not coach_list %}
There are some athletes and absolutely no coaches.
{% endif %}
Comparison operators are also available, and the use of filters is also
allowed, for example::
{% if articles|length >= 5 %}...{% endif %}
Arguments and operators _must_ have a space between them, so
``{% if 1>2 %}`` is not a valid if tag.
All supported operators are: ``or``, ``and``, ``in``, ``not in``
``==`` (or ``=``), ``!=``, ``>``, ``>=``, ``<`` and ``<=``.
Operator precedence follows Python.
"""
# {% if ... %}
bits = token.split_contents()[1:]
condition = TemplateIfParser(parser, bits).parse()
nodelist = parser.parse(('elif', 'else', 'endif'))
conditions_nodelists = [(condition, nodelist)]
token = parser.next_token()
# {% elif ... %} (repeatable)
while token.contents.startswith('elif'):
bits = token.split_contents()[1:]
condition = TemplateIfParser(parser, bits).parse()
nodelist = parser.parse(('elif', 'else', 'endif'))
conditions_nodelists.append((condition, nodelist))
token = parser.next_token()
# {% else %} (optional)
if token.contents == 'else':
nodelist = parser.parse(('endif',))
conditions_nodelists.append((None, nodelist))
token = parser.next_token()
# {% endif %}
assert token.contents == 'endif'
return IfNode(conditions_nodelists)
@register.tag
def ifchanged(parser, token):
"""
Checks if a value has changed from the last iteration of a loop.
The ``{% ifchanged %}`` block tag is used within a loop. It has two
possible uses.
1. Checks its own rendered contents against its previous state and only
displays the content if it has changed. For example, this displays a
list of days, only displaying the month if it changes::
<h1>Archive for {{ year }}</h1>
{% for date in days %}
{% ifchanged %}<h3>{{ date|date:"F" }}</h3>{% endifchanged %}
<a href="{{ date|date:"M/d"|lower }}/">{{ date|date:"j" }}</a>
{% endfor %}
2. If given one or more variables, check whether any variable has changed.
For example, the following shows the date every time it changes, while
showing the hour if either the hour or the date has changed::
{% for date in days %}
{% ifchanged date.date %} {{ date.date }} {% endifchanged %}
{% ifchanged date.hour date.date %}
{{ date.hour }}
{% endifchanged %}
{% endfor %}
"""
bits = token.contents.split()
nodelist_true = parser.parse(('else', 'endifchanged'))
token = parser.next_token()
if token.contents == 'else':
nodelist_false = parser.parse(('endifchanged',))
parser.delete_first_token()
else:
nodelist_false = NodeList()
values = [parser.compile_filter(bit) for bit in bits[1:]]
return IfChangedNode(nodelist_true, nodelist_false, *values)
@register.tag
def ssi(parser, token):
"""
Outputs the contents of a given file into the page.
Like a simple "include" tag, the ``ssi`` tag includes the contents
of another file -- which must be specified using an absolute path --
in the current page::
{% ssi "/home/html/ljworld.com/includes/right_generic.html" %}
If the optional "parsed" parameter is given, the contents of the included
file are evaluated as template code, with the current context::
{% ssi "/home/html/ljworld.com/includes/right_generic.html" parsed %}
"""
bits = token.split_contents()
parsed = False
if len(bits) not in (2, 3):
raise TemplateSyntaxError("'ssi' tag takes one argument: the path to"
" the file to be included")
if len(bits) == 3:
if bits[2] == 'parsed':
parsed = True
else:
raise TemplateSyntaxError("Second (optional) argument to %s tag"
" must be 'parsed'" % bits[0])
filepath = parser.compile_filter(bits[1])
return SsiNode(filepath, parsed)
@register.tag
def load(parser, token):
"""
Loads a custom template tag set.
For example, to load the template tags in
``django/templatetags/news/photos.py``::
{% load news.photos %}
Can also be used to load an individual tag/filter from
a library::
{% load byline from news %}
"""
bits = token.contents.split()
if len(bits) >= 4 and bits[-2] == "from":
try:
taglib = bits[-1]
lib = get_library(taglib)
except InvalidTemplateLibrary as e:
raise TemplateSyntaxError("'%s' is not a valid tag library: %s" %
(taglib, e))
else:
temp_lib = Library()
for name in bits[1:-2]:
if name in lib.tags:
temp_lib.tags[name] = lib.tags[name]
# a name could be a tag *and* a filter, so check for both
if name in lib.filters:
temp_lib.filters[name] = lib.filters[name]
elif name in lib.filters:
temp_lib.filters[name] = lib.filters[name]
else:
raise TemplateSyntaxError("'%s' is not a valid tag or filter in tag library '%s'" %
(name, taglib))
parser.add_library(temp_lib)
else:
for taglib in bits[1:]:
# add the library to the parser
try:
lib = get_library(taglib)
parser.add_library(lib)
except InvalidTemplateLibrary as e:
raise TemplateSyntaxError("'%s' is not a valid tag library: %s" %
(taglib, e))
return LoadNode()
@register.tag
def now(parser, token):
"""
Displays the date, formatted according to the given string.
Uses the same format as PHP's ``date()`` function; see http://php.net/date
for all the possible values.
Sample usage::
It is {% now "jS F Y H:i" %}
"""
bits = token.split_contents()
if len(bits) != 2:
raise TemplateSyntaxError("'now' statement takes one argument")
format_string = bits[1][1:-1]
return NowNode(format_string)
@register.tag
def regroup(parser, token):
"""
Regroups a list of alike objects by a common attribute.
This complex tag is best illustrated by use of an example: say that
``people`` is a list of ``Person`` objects that have ``first_name``,
``last_name``, and ``gender`` attributes, and you'd like to display a list
that looks like:
* Male:
* George Bush
* Bill Clinton
* Female:
* Margaret Thatcher
* Colendeeza Rice
* Unknown:
* Pat Smith
The following snippet of template code would accomplish this dubious task::
{% regroup people by gender as grouped %}
<ul>
{% for group in grouped %}
<li>{{ group.grouper }}
<ul>
{% for item in group.list %}
<li>{{ item }}</li>
{% endfor %}
</ul>
{% endfor %}
</ul>
As you can see, ``{% regroup %}`` populates a variable with a list of
objects with ``grouper`` and ``list`` attributes. ``grouper`` contains the
item that was grouped by; ``list`` contains the list of objects that share
that ``grouper``. In this case, ``grouper`` would be ``Male``, ``Female``
and ``Unknown``, and ``list`` is the list of people with those genders.
Note that ``{% regroup %}`` does not work when the list to be grouped is not
sorted by the key you are grouping by! This means that if your list of
people was not sorted by gender, you'd need to make sure it is sorted
before using it, i.e.::
{% regroup people|dictsort:"gender" by gender as grouped %}
"""
firstbits = token.contents.split(None, 3)
if len(firstbits) != 4:
raise TemplateSyntaxError("'regroup' tag takes five arguments")
target = parser.compile_filter(firstbits[1])
if firstbits[2] != 'by':
raise TemplateSyntaxError("second argument to 'regroup' tag must be 'by'")
lastbits_reversed = firstbits[3][::-1].split(None, 2)
if lastbits_reversed[1][::-1] != 'as':
raise TemplateSyntaxError("next-to-last argument to 'regroup' tag must"
" be 'as'")
var_name = lastbits_reversed[0][::-1]
# RegroupNode will take each item in 'target', put it in the context under
# 'var_name', evaluate 'var_name'.'expression' in the current context, and
# group by the resulting value. After all items are processed, it will
# save the final result in the context under 'var_name', thus clearing the
# temporary values. This hack is necessary because the template engine
# doesn't provide a context-aware equivalent of Python's getattr.
expression = parser.compile_filter(var_name +
VARIABLE_ATTRIBUTE_SEPARATOR +
lastbits_reversed[2][::-1])
return RegroupNode(target, expression, var_name)
@register.tag
def spaceless(parser, token):
"""
Removes whitespace between HTML tags, including tab and newline characters.
Example usage::
{% spaceless %}
<p>
<a href="foo/">Foo</a>
</p>
{% endspaceless %}
This example would return this HTML::
<p><a href="foo/">Foo</a></p>
Only space between *tags* is normalized -- not space between tags and text.
In this example, the space around ``Hello`` won't be stripped::
{% spaceless %}
<strong>
Hello
</strong>
{% endspaceless %}
"""
nodelist = parser.parse(('endspaceless',))
parser.delete_first_token()
return SpacelessNode(nodelist)
@register.tag
def templatetag(parser, token):
"""
Outputs one of the bits used to compose template tags.
Since the template system has no concept of "escaping", to display one of
the bits used in template tags, you must use the ``{% templatetag %}`` tag.
The argument tells which template bit to output:
================== =======
Argument Outputs
================== =======
``openblock`` ``{%``
``closeblock`` ``%}``
``openvariable`` ``{{``
``closevariable`` ``}}``
``openbrace`` ``{``
``closebrace`` ``}``
``opencomment`` ``{#``
``closecomment`` ``#}``
================== =======
"""
bits = token.contents.split()
if len(bits) != 2:
raise TemplateSyntaxError("'templatetag' statement takes one argument")
tag = bits[1]
if tag not in TemplateTagNode.mapping:
raise TemplateSyntaxError("Invalid templatetag argument: '%s'."
" Must be one of: %s" %
(tag, TemplateTagNode.mapping.keys()))
return TemplateTagNode(tag)
@register.tag
def url(parser, token):
"""
Returns an absolute URL matching given view with its parameters.
This is a way to define links that aren't tied to a particular URL
configuration::
{% url "path.to.some_view" arg1 arg2 %}
or
{% url "path.to.some_view" name1=value1 name2=value2 %}
The first argument is a path to a view. It can be an absolute Python path
or just ``app_name.view_name`` without the project name if the view is
located inside the project.
Other arguments are space-separated values that will be filled in place of
positional and keyword arguments in the URL. Don't mix positional and
keyword arguments.
All arguments for the URL should be present.
For example if you have a view ``app_name.client`` taking client's id and
the corresponding line in a URLconf looks like this::
('^client/(\d+)/$', 'app_name.client')
and this app's URLconf is included into the project's URLconf under some
path::
('^clients/', include('project_name.app_name.urls'))
then in a template you can create a link for a certain client like this::
{% url "app_name.client" client.id %}
The URL will look like ``/clients/client/123/``.
The first argument can also be a named URL instead of the Python path to
the view callable. For example if the URLconf entry looks like this::
url('^client/(\d+)/$', name='client-detail-view')
then in the template you can use::
{% url "client-detail-view" client.id %}
There is even another possible value type for the first argument. It can be
the name of a template variable that will be evaluated to obtain the view
name or the URL name, e.g.::
{% with view_path="app_name.client" %}
{% url view_path client.id %}
{% endwith %}
or,
{% with url_name="client-detail-view" %}
{% url url_name client.id %}
{% endwith %}
"""
bits = token.split_contents()
if len(bits) < 2:
raise TemplateSyntaxError("'%s' takes at least one argument"
" (path to a view)" % bits[0])
viewname = parser.compile_filter(bits[1])
args = []
kwargs = {}
asvar = None
bits = bits[2:]
if len(bits) >= 2 and bits[-2] == 'as':
asvar = bits[-1]
bits = bits[:-2]
if len(bits):
for bit in bits:
match = kwarg_re.match(bit)
if not match:
raise TemplateSyntaxError("Malformed arguments to url tag")
name, value = match.groups()
if name:
kwargs[name] = parser.compile_filter(value)
else:
args.append(parser.compile_filter(value))
return URLNode(viewname, args, kwargs, asvar)
@register.tag
def verbatim(parser, token):
"""
Stops the template engine from rendering the contents of this block tag.
Usage::
{% verbatim %}
{% don't process this %}
{% endverbatim %}
You can also designate a specific closing tag block (allowing the
unrendered use of ``{% endverbatim %}``)::
{% verbatim myblock %}
...
{% endverbatim myblock %}
"""
nodelist = parser.parse(('endverbatim',))
parser.delete_first_token()
return VerbatimNode(nodelist.render(Context()))
@register.tag
def widthratio(parser, token):
"""
For creating bar charts and such, this tag calculates the ratio of a given
value to a maximum value, and then applies that ratio to a constant.
For example::
<img src='bar.gif' height='10' width='{% widthratio this_value max_value 100 %}' />
Above, if ``this_value`` is 175 and ``max_value`` is 200, the image in
the above example will be 88 pixels wide (because 175/200 = .875;
.875 * 100 = 87.5 which is rounded up to 88).
"""
bits = token.contents.split()
if len(bits) != 4:
raise TemplateSyntaxError("widthratio takes three arguments")
tag, this_value_expr, max_value_expr, max_width = bits
return WidthRatioNode(parser.compile_filter(this_value_expr),
parser.compile_filter(max_value_expr),
parser.compile_filter(max_width))
@register.tag('with')
def do_with(parser, token):
"""
Adds one or more values to the context (inside of this block) for caching
and easy access.
For example::
{% with total=person.some_sql_method %}
{{ total }} object{{ total|pluralize }}
{% endwith %}
Multiple values can be added to the context::
{% with foo=1 bar=2 %}
...
{% endwith %}
The legacy format of ``{% with person.some_sql_method as total %}`` is
still accepted.
"""
bits = token.split_contents()
remaining_bits = bits[1:]
extra_context = token_kwargs(remaining_bits, parser, support_legacy=True)
if not extra_context:
raise TemplateSyntaxError("%r expected at least one variable "
"assignment" % bits[0])
if remaining_bits:
raise TemplateSyntaxError("%r received an invalid token: %r" %
(bits[0], remaining_bits[0]))
nodelist = parser.parse(('endwith',))
parser.delete_first_token()
return WithNode(None, None, nodelist, extra_context=extra_context)
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