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, list(TemplateTagNode.mapping.keys())))
return TemplateTagNode(tag)
def top(self):
countervar = None
counter = None
extra_context = {}
while self.more():
tag = self.tag()
if tag == 'with' or tag == 'and':
value = self.value()
if self.tag() != 'as':
raise TemplateSyntaxError(
"variable bindings in 'blocktrans' must be 'with value as variable'"
)
extra_context[self.tag()] = VariableNode(
parser.compile_filter(value))
elif tag == 'count':
counter = parser.compile_filter(self.value())
if self.tag() != 'as':
raise TemplateSyntaxError(
"counter specification in 'blocktrans' must be 'count value as variable'"
)
countervar = self.tag()
else:
raise TemplateSyntaxError(
"unknown subtag %s for 'blocktrans' found" % tag)
return (countervar, counter, extra_context)
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.contents.split()
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])
return SsiNode(bits[1], parsed)
def autoescape(parser, token):
"""
Force autoescape behaviour 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)
def render_node(self, node, context):
try:
result = node.render(context)
except TemplateSyntaxError as e:
if not hasattr(e, 'source'):
e.source = node.source
raise
except Exception as e:
from sys import exc_info
wrapped = TemplateSyntaxError('Caught %s while rendering: %s' %
(e.__class__.__name__, force_unicode(e, errors='replace')))
wrapped.source = node.source
wrapped.exc_info = exc_info()
raise wrapped.with_traceback(wrapped.exc_info[2])
return result
def do_cache(parser, token):
"""
This will cache the contents of a template fragment for a given amount
of time.
Usage::
{% load cache %}
{% cache [expire_time] [fragment_name] %}
.. some expensive processing ..
{% endcache %}
This tag also supports varying by a list of arguments::
{% load cache %}
{% cache [expire_time] [fragment_name] [var1] [var2] .. %}
.. some expensive processing ..
{% endcache %}
Each unique set of arguments will result in a unique cache entry.
"""
nodelist = parser.parse(('endcache', ))
parser.delete_first_token()
tokens = token.contents.split()
if len(tokens) < 3:
raise TemplateSyntaxError("'%r' tag requires at least 2 arguments." %
tokens[0])
return CacheNode(nodelist, tokens[1], tokens[2], tokens[3:])
def top(self):
value = self.value()
# Backwards Compatiblity fix:
# FilterExpression does not support single-quoted strings,
# so we make a cheap localized fix in order to maintain
# backwards compatibility with existing uses of ``trans``
# where single quote use is supported.
if value[0] == "'":
pos = None
m = re.match("^'([^']+)'(\|.*$)", value)
if m:
value = '"%s"%s' % (m.group(1).replace('"',
'\\"'), m.group(2))
elif value[-1] == "'":
value = '"%s"' % value[1:-1].replace('"', '\\"')
if self.more():
if self.tag() == 'noop':
noop = True
else:
raise TemplateSyntaxError(
"only option for 'trans' is 'noop'")
else:
noop = False
return (value, noop)
def render(self, context):
try:
expire_time = self.expire_time_var.resolve(context)
except VariableDoesNotExist:
raise TemplateSyntaxError('"cache" tag got an unknown variable: %r' % self.expire_time_var.var)
try:
expire_time = int(expire_time)
except (ValueError, TypeError):
raise TemplateSyntaxError('"cache" tag got a non-integer timeout value: %r' % expire_time)
# Build a unicode key for this fragment and all vary-on's.
args = md5_constructor(u':'.join([urlquote(resolve_variable(var, context)) for var in self.vary_on]))
cache_key = 'template.cache.%s.%s' % (self.fragment_name, args.hexdigest())
value = cache.get(cache_key)
if value is None:
value = self.nodelist.render(context)
cache.set(cache_key, value, expire_time)
return value
def do_block(parser, token):
"""
Define a block that can be overridden by child templates.
"""
bits = token.contents.split()
if len(bits) != 2:
raise TemplateSyntaxError("'%s' tag takes only one argument" % bits[0])
block_name = bits[1]
# Keep track of the names of BlockNodes found in this template, so we can
# check for duplication.
try:
if block_name in parser.__loaded_blocks:
raise TemplateSyntaxError("'%s' tag with name '%s' appears more than once" % (bits[0], block_name))
parser.__loaded_blocks.append(block_name)
except AttributeError: # parser.__loaded_blocks isn't a list yet
parser.__loaded_blocks = [block_name]
nodelist = parser.parse(('endblock', 'endblock %s' % block_name))
parser.delete_first_token()
return BlockNode(block_name, nodelist)
def get_parent(self, context):
if self.parent_name_expr:
self.parent_name = self.parent_name_expr.resolve(context)
parent = self.parent_name
if not parent:
error_msg = "Invalid template name in 'extends' tag: %r." % parent
if self.parent_name_expr:
error_msg += " Got this from the '%s' variable." % self.parent_name_expr.token
raise TemplateSyntaxError(error_msg)
if hasattr(parent, 'render'):
return parent # parent is a Template object
return get_template(parent)
def do_extends(parser, token):
"""
Signal that this template extends a parent template.
This tag may be used in two ways: ``{% extends "base" %}`` (with quotes)
uses the literal value "base" as the name of the parent template to extend,
or ``{% extends variable %}`` uses the value of ``variable`` as either the
name of the parent template to extend (if it evaluates to a string) or as
the parent tempate itelf (if it evaluates to a Template object).
"""
bits = token.split_contents()
if len(bits) != 2:
raise TemplateSyntaxError("'%s' takes one argument" % bits[0])
parent_name, parent_name_expr = None, None
if bits[1][0] in ('"', "'") and bits[1][-1] == bits[1][0]:
parent_name = bits[1][1:-1]
else:
parent_name_expr = parser.compile_filter(bits[1])
nodelist = parser.parse()
if nodelist.get_nodes_by_type(ExtendsNode):
raise TemplateSyntaxError("'%s' cannot appear more than once in the same template" % bits[0])
return ExtendsNode(nodelist, parent_name, parent_name_expr)
def do_include(parser, token):
"""
Loads a template and renders it with the current context.
Example::
{% include "foo/some_include" %}
"""
bits = token.split_contents()
if len(bits) != 2:
raise TemplateSyntaxError("%r tag takes one argument: the name of the template to be included" % bits[0])
path = bits[1]
if path[0] in ('"', "'") and path[-1] == path[0]:
return ConstantIncludeNode(path[1:-1])
return IncludeNode(bits[1])
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)
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.contents.split('"')
if len(bits) != 3:
raise TemplateSyntaxError("'now' statement takes one argument")
format_string = bits[1]
return NowNode(format_string)
def render(self, context):
try:
value = self.val_expr.resolve(context)
maxvalue = 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)
maxvalue = float(maxvalue)
ratio = (value / maxvalue) * max_width
except (ValueError, ZeroDivisionError):
return ''
return str(int(round(ratio)))
def do_get_current_language_bidi(parser, token):
"""
This will store the current language layout in the context.
Usage::
{% get_current_language_bidi as bidi %}
This will fetch the currently active language's layout and
put it's value into the ``bidi`` context variable.
True indicates right-to-left layout, otherwise left-to-right
"""
args = token.contents.split()
if len(args) != 3 or args[1] != 'as':
raise TemplateSyntaxError("'get_current_language_bidi' requires 'as variable' (got %r)" % args)
return GetCurrentLanguageBidiNode(args[2])
def do_get_current_language(parser, token):
"""
This will store the current language in the context.
Usage::
{% get_current_language as language %}
This will fetch the currently active language and
put it's value into the ``language`` context
variable.
"""
args = token.contents.split()
if len(args) != 3 or args[1] != 'as':
raise TemplateSyntaxError("'get_current_language' requires 'as variable' (got %r)" % args)
return GetCurrentLanguageNode(args[2])
class DebugNodeList(NodeList):
def render_node(self, node, context):
try:
result = node.render(context)
except TemplateSyntaxError, e:
if not hasattr(e, 'source'):
e.source = node.source
raise
except Exception, e:
from sys import exc_info
wrapped = TemplateSyntaxError(
u'Caught %s while rendering: %s' %
(e.__class__.__name__, force_unicode(e, errors='replace')))
wrapped.source = node.source
wrapped.exc_info = exc_info()
raise wrapped, None, wrapped.exc_info[2]
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 %}
"""
bits = token.contents.split()
for taglib in bits[1:]:
# add the library to the parser
try:
lib = get_library(taglib)
parser.add_library(lib)
except InvalidTemplateLibrary, e:
raise TemplateSyntaxError("'%s' is not a valid tag library: %s" %
(taglib, e))
def do_with(parser, token):
"""
Adds a value to the context (inside of this block) for caching and easy
access.
For example::
{% with person.some_sql_method as total %}
{{ total }} object{{ total|pluralize }}
{% endwith %}
"""
bits = list(token.split_contents())
if len(bits) != 4 or bits[2] != "as":
raise TemplateSyntaxError("%r expected format is 'value as name'" %
bits[0])
var = parser.compile_filter(bits[1])
name = bits[3]
nodelist = parser.parse(('endwith',))
parser.delete_first_token()
return WithNode(var, name, nodelist)
def do_get_available_languages(parser, token):
"""
This will store a list of available languages
in the context.
Usage::
{% get_available_languages as languages %}
{% for language in languages %}
...
{% endfor %}
This will just pull the LANGUAGES setting from
your setting file (or the default settings) and
put it into the named variable.
"""
args = token.contents.split()
if len(args) != 3 or args[1] != 'as':
raise TemplateSyntaxError("'get_available_languages' requires 'as variable' (got %r)" % args)
return GetAvailableLanguagesNode(args[2])
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 %}
"""
_, 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)
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))
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])
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 comma-separated values
that will be filled in place of positional and keyword arguments in the
URL. 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/``.
"""
bits = token.split_contents()
if len(bits) < 2:
raise TemplateSyntaxError("'%s' takes at least one argument"
" (path to a view)" % bits[0])
viewname = bits[1]
args = []
kwargs = {}
asvar = None
bits = bits[2:]
if len(bits) >= 2 and bits[-2] == 'as':
asvar = bits[-1]
bits = bits[:-2]
# Backwards compatibility: check for the old comma separated format
# {% url urlname arg1,arg2 %}
# Initial check - that the first space separated bit has a comma in it
if bits and ',' in bits[0]:
check_old_format = True
# In order to *really* be old format, there must be a comma
# in *every* space separated bit, except the last.
for bit in bits[1:-1]:
if ',' not in bit:
# No comma in this bit. Either the comma we found
# in bit 1 was a false positive (e.g., comma in a string),
# or there is a syntax problem with missing commas
check_old_format = False
break
else:
# No comma found - must be new format.
check_old_format = False
if check_old_format:
# Confirm that this is old format by trying to parse the first
# argument. An exception will be raised if the comma is
# unexpected (i.e. outside of a static string).
match = kwarg_re.match(bits[0])
if match:
value = match.groups()[1]
try:
parser.compile_filter(value)
except TemplateSyntaxError:
bits = ''.join(bits).split(',')
# Now all the bits are parsed into new format,
# process them as template vars
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)
def source_error(self, source, msg):
e = TemplateSyntaxError(msg)
e.source = source
return e
def do_block_translate(parser, token):
"""
This will translate a block of text with parameters.
Usage::
{% blocktrans with foo|filter as bar and baz|filter as boo %}
This is {{ bar }} and {{ boo }}.
{% endblocktrans %}
Additionally, this supports pluralization::
{% blocktrans count var|length as count %}
There is {{ count }} object.
{% plural %}
There are {{ count }} objects.
{% endblocktrans %}
This is much like ngettext, only in template syntax.
"""
class BlockTranslateParser(TokenParser):
def top(self):
countervar = None
counter = None
extra_context = {}
while self.more():
tag = self.tag()
if tag == 'with' or tag == 'and':
value = self.value()
if self.tag() != 'as':
raise TemplateSyntaxError("variable bindings in 'blocktrans' must be 'with value as variable'")
extra_context[self.tag()] = VariableNode(
parser.compile_filter(value))
elif tag == 'count':
counter = parser.compile_filter(self.value())
if self.tag() != 'as':
raise TemplateSyntaxError("counter specification in 'blocktrans' must be 'count value as variable'")
countervar = self.tag()
else:
raise TemplateSyntaxError("unknown subtag %s for 'blocktrans' found" % tag)
return (countervar, counter, extra_context)
countervar, counter, extra_context = BlockTranslateParser(token.contents).top()
singular = []
plural = []
while parser.tokens:
token = parser.next_token()
if token.token_type in (TOKEN_VAR, TOKEN_TEXT):
singular.append(token)
else:
break
if countervar and counter:
if token.contents.strip() != 'plural':
raise TemplateSyntaxError("'blocktrans' doesn't allow other block tags inside it")
while parser.tokens:
token = parser.next_token()
if token.token_type in (TOKEN_VAR, TOKEN_TEXT):
plural.append(token)
else:
break
if token.contents.strip() != 'endblocktrans':
raise TemplateSyntaxError("'blocktrans' doesn't allow other block tags (seen %r) inside it" % token.contents)
return BlockTranslateNode(extra_context, singular, plural, countervar,
counter)
def source_error(self, source,msg):
e = TemplateSyntaxError(msg)
e.source = source
return e
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'")
expression = parser.compile_filter(lastbits_reversed[2][::-1])
var_name = lastbits_reversed[0][::-1]
return RegroupNode(target, expression, var_name)
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.
"""
# 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]
if len(args) > 4 and args[-2] == 'as':
name = args[-1]
values = [parser.compile_filter(arg) for arg in args[1:-2]]
node = CycleNode(values, name)
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
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.sub(r' *, *', ',', ' '.join(bits[1:in_index])).split(',')
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)