1 Template Designer Documentation
2 ===============================
4 .. highlight:: html+jinja
6 This document describes the syntax and semantics of the template engine and
7 will be most useful as reference to those creating Jinja templates. As the
8 template engine is very flexible the configuration from the application might
9 be slightly different from here in terms of delimiters and behavior of
16 A template is simply a text file. It can generate any text-based format
17 (HTML, XML, CSV, LaTeX, etc.). It doesn't have a specific extension,
18 ``.html`` or ``.xml`` are just fine.
20 A template contains **variables** or **expressions**, which get replaced with
21 values when the template is evaluated, and tags, which control the logic of
22 the template. The template syntax is heavily inspired by Django and Python.
24 Below is a minimal template that illustrates a few basics. We will cover
25 the details later in that document::
27 <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN">
30 <title>My Webpage</title>
34 {% for item in navigation %}
35 <li><a href="{{ item.href }}">{{ item.caption }}</a></li>
44 This covers the default settings. The application developer might have
45 changed the syntax from ``{% foo %}`` to ``<% foo %>`` or something similar.
47 There are two kinds of delimiers. ``{% ... %}`` and ``{{ ... }}``. The first
48 one is used to execute statements such as for-loops or assign values, the
49 latter prints the result of the expression to the template.
56 The application passes variables to the templates you can mess around in the
57 template. Variables may have attributes or elements on them you can access
58 too. How a variable looks like, heavily depends on the application providing
61 You can use a dot (``.``) to access attributes of a variable, alternative the
62 so-called "subscribe" syntax (``[]``) can be used. The following lines do
68 It's important to know that the curly braces are *not* part of the variable
69 but the print statement. If you access variables inside tags don't put the
72 If a variable or attribute does not exist you will get back an undefined
73 value. What you can do with that kind of value depends on the application
74 configuration, the default behavior is that it evaluates to an empty string
75 if printed and that you can iterate over it, but every other operation fails.
82 Variables can by modified by **filters**. Filters are separated from the
83 variable by a pipe symbol (``|``) and may have optional arguments in
84 parentheses. Multiple filters can be chained. The output of one filter is
87 ``{{ name|striptags|title }}`` for example will remove all HTML Tags from the
88 `name` and title-cases it. Filters that accept arguments have parentheses
89 around the arguments, like a function call. This example will join a list
90 by spaces: ``{{ list|join(', ') }}``.
92 The :ref:`builtin-filters` below describes all the builtin filters.
99 Beside filters there are also so called "tests" available. Tests can be used
100 to test a variable against a common expression. To test a variable or
101 expression you add `is` plus the name of the test after the variable. For
102 example to find out if a variable is defined you can do ``name is defined``
103 which will then return true or false depending on if `name` is defined.
105 Tests can accept arguments too. If the test only takes one argument you can
106 leave out the parentheses to group them. For example the following two
107 expressions do the same::
109 {% if loop.index is divisibleby 3 %}
110 {% if loop.index is divisibleby(3) %}
112 The :ref:`builtin-tests` below describes all the builtin tests.
118 To comment-out part of a line in a template, use the comment syntax which is
119 by default set to ``{# ... #}``. This is useful to comment out parts of the
120 template for debugging or to add information for other template designers or
123 {# note: disabled template because we no longer user this
124 {% for user in users %}
133 In the default configuration whitespace is not further modified by the
134 template engine, so each whitespace (spaces, tabs, newlines etc.) is returned
135 unchanged. If the application configures Jinja to `trim_blocks` the first
136 newline after a a template tag is removed automatically (like in PHP).
138 But you can also strip whitespace in templates by hand. If you put an minus
139 sign (``-``) to the start or end of an block (for example a for tag), a
140 comment or variable expression you can remove the whitespaces after or before
143 {% for item in seq -%}
147 This will yield all elements without whitespace between them. If `seq` was
148 a list of numbers from ``1`` to ``9`` the output would be ``123456789``.
150 Note that you must not use a whitespace between the tag and the minus sign:
153 {%- if foo -%}...{% endif %}
157 {% - if foo - %}...{% endif %}
159 If :ref:`line-statements` are enabled they strip leading whitespace
160 automatically up to the beginning of the line.
166 It is sometimes desirable or even necessary to have Jinja ignore parts it
167 would otherwise handle as variables or blocks. For example if the default
168 syntax is used and you want to use ``{{`` as raw string in the template and
169 not start a variable you have to use a trick.
171 The easiest way is to output the variable delimiter (``{{``) by using a
172 variable expression::
176 For bigger sections it makes sense to mark a block `raw`. For example to
177 put Jinja syntax as example into a template you can use this snippet::
181 {% for item in seq %}
193 If line statements are enabled by the application it's possible to mark a
194 line as a statement. For example if the line statement prefix is configured
195 to ``#`` the following two examples are equivalent::
204 {% for item in seq %}
209 The line statement prefix can appear anywhere on the line as long as no text
210 precedes it. For better readability statements that start a block (such as
211 `for`, `if`, `elif` etc.) may end with a colon::
218 .. _template-inheritance:
223 The most powerful part of Jinja is template inheritance. Template inheritance
224 allows you to build a base "skeleton" template that contains all the common
225 elements of your site and defines **blocks** that child templates can override.
227 Sounds complicated but is very basic. It's easiest to understand it by starting
234 This template, which we'll call ``base.html``, defines a simple HTML skeleton
235 document that you might use for a simple two-column page. It's the job of
236 "child" templates to fill the empty blocks with content::
238 <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN">
240 <html xmlns="http://www.w3.org/1999/xhtml">
243 <link rel="stylesheet" href="style.css" />
244 <title>{% block title %}{% endblock %} - My Webpage</title>
248 <div id="content">{% block content %}{% endblock %}</div>
251 © Copyright 2008 by <a href="http://domain.invalid/">you</a>.
256 In this example, the ``{% block %}`` tags define four blocks that child templates
257 can fill in. All the `block` tag does is to tell the template engine that a
258 child template may override those portions of the template.
263 A child template might look like this::
265 {% extends "base.html" %}
266 {% block title %}Index{% endblock %}
269 <style type="text/css">
270 .important { color: #336699; }
275 <p class="important">
276 Welcome on my awsome homepage.
280 The ``{% extends %}`` tag is the key here. It tells the template engine that
281 this template "extends" another template. When the template system evaluates
282 this template, first it locates the parent. The extends tag should be the
283 first tag in the template. Everything before it is printed out normally and
284 may cause confusion. For details about this behavior and how to take
285 advantage of it, see :ref:`null-master-fallback`.
287 The filename of the template depends on the template loader. For example the
288 :class:`FileSystemLoader` allows you to access other templates by giving the
289 filename. You can access templates in subdirectories with an slash::
291 {% extends "layout/default.html" %}
293 But this behavior can depend on the application embedding Jinja. Note that
294 since the child template doesn't define the ``footer`` block, the value from
295 the parent template is used instead.
297 You can't define multiple ``{% block %}`` tags with the same name in the
298 same template. This limitation exists because a block tag works in "both"
299 directions. That is, a block tag doesn't just provide a hole to fill - it
300 also defines the content that fills the hole in the *parent*. If there
301 were two similarly-named ``{% block %}`` tags in a template, that template's
302 parent wouldn't know which one of the blocks' content to use.
304 If you want to print a block multiple times you can however use the special
305 `self` variable and call the block with that name::
307 <title>{% block title %}{% endblock %}</title>
308 <h1>{{ self.title() }}</h1>
309 {% block body %}{% endblock %}
312 Unlike Python Jinja does not support multiple inheritance. So you can only have
313 one extends tag called per rendering.
319 It's possible to render the contents of the parent block by calling `super`.
320 This gives back the results of the parent block::
323 <h3>Table Of Contents</h3>
332 When generating HTML from templates, there's always a risk that a variable will
333 include characters that affect the resulting HTML. There are two approaches:
334 manually escaping each variable or automatically escaping everything by default.
336 Jinja supports both, but what is used depends on the application configuration.
337 The default configuaration is no automatic escaping for various reasons:
339 - escaping everything except of safe values will also mean that Jinja is
340 escaping variables known to not include HTML such as numbers which is
341 a huge performance hit.
343 - The information about the safety of a variable is very fragile. It could
344 happen that by coercing safe and unsafe values the return value is double
347 Working with Manual Escaping
348 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~
350 If manual escaping is enabled it's **your** responsibility to escape
351 variables if needed. What to escape? If you have a variable that *may*
352 include any of the following chars (``>``, ``<``, ``&``, or ``"``) you
353 **have to** escape it unless the variable contains well-formed and trusted
354 HTML. Escaping works by piping the variable through the ``|e`` filter:
355 ``{{ user.username|e }}``.
357 Working with Automatic Escaping
358 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
360 When automatic escaping is enabled everything is escaped by default except
361 for values explicitly marked as safe. Those can either be marked by the
362 application or in the template by using the `|safe` filter. The main
363 problem with this approach is that Python itself doesn't have the concept
364 of tainted values so the information if a value is safe or unsafe can get
365 lost. If the information is lost escaping will take place which means that
366 you could end up with double escaped contents.
368 Double escaping is easy to avoid however, just rely on the tools Jinja2
369 provides and don't use builtin Python constructs such as the string modulo
372 Functions returning template data (macros, `super`, `self.BLOCKNAME`) return
375 String literals in templates with automatic escaping are considered unsafe
376 too. The reason for this is that the safe string is an extension to Python
377 and not every library will work properly with it.
380 List of Control Structures
381 --------------------------
383 A control structure refers to all those things that control the flow of a
384 program - conditionals (i.e. if/elif/else), for-loops, as well as things like
385 macros and blocks. Control structures appear inside ``{% ... %}`` blocks
386 in the default syntax.
391 Loop over each item in a sequence. For example, to display a list of users
392 provided in a variable called `users`::
396 {% for user in users %}
397 <li>{{ user.username|e }}</li>
401 Inside of a for loop block you can access some special variables:
403 +-----------------------+---------------------------------------------------+
404 | Variable | Description |
405 +=======================+===================================================+
406 | `loop.index` | The current iteration of the loop. (1 indexed) |
407 +-----------------------+---------------------------------------------------+
408 | `loop.index0` | The current iteration of the loop. (0 indexed) |
409 +-----------------------+---------------------------------------------------+
410 | `loop.revindex` | The number of iterations from the end of the loop |
412 +-----------------------+---------------------------------------------------+
413 | `loop.revindex0` | The number of iterations from the end of the loop |
415 +-----------------------+---------------------------------------------------+
416 | `loop.first` | True if first iteration. |
417 +-----------------------+---------------------------------------------------+
418 | `loop.last` | True if last iteration. |
419 +-----------------------+---------------------------------------------------+
420 | `loop.length` | The number of items in the sequence. |
421 +-----------------------+---------------------------------------------------+
422 | `loop.cycle` | A helper function to cycle between a list of |
423 | | sequences. See the explanation below. |
424 +-----------------------+---------------------------------------------------+
426 Within a for-loop, it's possible to cycle among a list of strings/variables
427 each time through the loop by using the special `loop.cycle` helper::
429 {% for row in rows %}
430 <li class="{{ loop.cycle('odd', 'even') }}">{{ row }}</li>
435 Unlike in Python it's not possible to `break` or `continue` in a loop. You
436 can however filter the sequence during iteration which allows you to skip
437 items. The following example skips all the users which are hidden::
439 {% for user in users if not user.hidden %}
440 <li>{{ user.username|e }}</li>
443 The advantage is that the special `loop` variable will count correctly thus
444 not counting the users not iterated over.
446 If no iteration took place because the sequence was empty or the filtering
447 removed all the items from the sequence you can render a replacement block
451 {% for user in users %}
452 <li>{{ user.username|e }}</li>
454 <li><em>no users found</em></li>
458 It is also possible to use loops recursively. This is useful if you are
459 dealing with recursive data such as sitemaps. To use loops recursively you
460 basically have to add the `recursive` modifier to the loop definition and
461 call the `loop` variable with the new iterable where you want to recurse.
463 The following example implements a sitemap with recursive loops::
466 {%- for item in sitemap recursive %}
467 <li><a href="{{ item.href|e }}">{{ item.title }}</a>
468 {%- if item.children -%}
469 <ul class="submenu">{{ loop(item.children) }}</ul>
478 The `if` statement in Jinja is comparable with the if statements of Python.
479 In the simplest form you can use it to test if a variable is defined, not
484 {% for user in users %}
485 <li>{{ user.username|e }}</li>
490 For multiple branches `elif` and `else` can be used like in Python. You can
491 use more complex :ref:`expressions` there too::
495 {% elif kenny.dead %}
496 You killed Kenny! You bastard!!!
498 Kenny looks okay --- so far
501 If can also be used as :ref:`inline expression <if-expression>` and for
502 :ref:`loop filtering <loop-filtering>`.
508 Macros are comparable with functions in regular programming languages. They
509 are useful to put often used idioms into reusable functions to not repeat
512 Macros can be defined in helper templates which then are :ref:`imported
513 <import>` or directly in the template where they are used. There is one big
514 difference between those two possibilities. A macro that is defined in the
515 template where it's also used has access to the context passed to the template.
516 A macro defined in another template and then imported can only access variables
517 defined there or in the global context.
519 Here a small example of a macro that renders a form element::
521 {% macro input(name, value='', type='text', size=20) -%}
522 <input type="{{ type }}" name="{{ name }}" value="{{
523 value|e }}" size="{{ size }}">
526 The macro can then be called like a function in the namespace::
528 <p>{{ input('username') }}</p>
529 <p>{{ input('password', type='password') }}</p>
531 If the macro was defined in a different template you have to
532 :ref:`import <import>` it first.
534 Inside macros you have access to three special variables:
537 If more positional arguments are passed to the macro than accepted by the
538 macro they end up in the special `varargs` variable as list of values.
541 Like `varargs` but for keyword arguments. All unconsumed keyword
542 arguments are stored in this special variable.
545 If the macro was called from a :ref:`call<call>` tag the caller is stored
546 in this variable as macro which can be called.
548 Macros also expose some of their internal details. The following attributes
549 are available on a macro object:
552 The name of the macro. ``{{ input.name }}`` will print ``input``.
555 A tuple of the names of arguments the macro accepts.
558 A tuple of default values.
561 This is `true` if the macro accepts extra keyword arguments (ie: accesses
562 the special `kwargs` variable).
565 This is `true` if the macro accepts extra positional arguments (ie:
566 accesses the special `varargs` variable).
569 This is `true` if the macro accesses the special `caller` variable and may
570 be called from a :ref:`call<call>` tag.
578 In some cases it can be useful to pass a macro to another macro. For this
579 purpose you can use the special `call` block. The following example shows
580 a macro that takes advantage of the call functionality and how it can be
583 {% macro render_dialog(title, class='dialog') -%}
584 <div class="{{ class }}">
586 <div class="contents">
592 {% call render_dialog('Hello World') %}
593 This is a simple dialog rendered by using a macro and
597 It's also possible to pass arguments back to the call block. This makes it
598 useful as replacement for loops. It is however not possible to call a
599 call block with another call block.
601 Here an example of how a call block can be used with arguments::
603 {% macro dump_users(users) -%}
605 {%- for user in users %}
606 <li><p>{{ user.username|e }}</p>{{ caller(user) }}</li>
611 {% call(user) dump_users(list_of_user) %}
614 <dd>{{ user.realname|e }}</dd>
616 <dd>{{ user.description }}</dd>
624 Inside code blocks you can also assign values to variables. Assignments at
625 top level (outside of blocks, macros or loops) are exported from the template
626 like top level macros and can be imported by other templates.
628 Assignments use the `set` tag and can have multiple targets::
630 {% set navigation = [('index.html', 'Index'), ('about.html', 'About')] %}
631 {% set key, value = call_something() %}
637 The `extends` tag can be used to extend a template from another one. You
638 can have multiple of them in a file but only one of them may be executed
639 at the time. There is no support for multiple inheritance. See the section
640 about :ref:`template-inheritance` above.
646 Blocks are used for inheritance and act as placeholders and replacements
647 at the same time. They are documented in detail as part of the section
648 about :ref:`template-inheritance`.
654 The `include` statement is useful to include a template and return the
655 rendered contents of that file into the current namespace::
657 {% include 'header.html' %}
659 {% include 'footer.html' %}
661 Included templates have access to the variables of the active context by
662 default. For more details about context behavior of imports and includes
663 see :ref:`import-visibility`.
670 Jinja2 supports putting often used code into macros. These macros can go into
671 different templates and get imported from there. This works similar to the
672 import statements in Python. It's important to know that imports are cached
673 and imported templates don't have access to the current template variables,
674 just the globals by defualt. For more details about context behavior of
675 imports and includes see :ref:`import-visibility`.
677 There are two ways to import templates. You can import the complete template
678 into a variable or request specific macros / exported variables from it.
680 Imagine we have a helper module that renders forms (called `forms.html`)::
682 {% macro input(name, value='', type='text') -%}
683 <input type="{{ type }}" value="{{ value|e }}" name="{{ name }}">
686 {%- macro textarea(name, value='', rows=10, cols=40) -%}
687 <textarea name="{{ name }}" rows="{{ rows }}" cols="{{ cols
688 }}">{{ value|e }}</textarea>
691 The easiest and most flexible is importing the whole module into a variable.
692 That way you can access the attributes::
694 {% import 'forms.html' as forms %}
697 <dd>{{ forms.input('username') }}</dd>
699 <dd>{{ forms.input('password', type='password') }}</dd>
701 <p>{{ forms.textarea('comment') }}</p>
704 Alternatively you can import names from the template into the current
707 {% from 'forms.html' import input as input_field, textarea %}
710 <dd>{{ input_field('username') }}</dd>
712 <dd>{{ input_field('password', type='password') }}</dd>
714 <p>{{ textarea('comment') }}</p>
717 .. _import-visibility:
719 Import Context Behavior
720 -----------------------
722 Per default included templates are passed the current context and imported
723 templates not. The reason for this is that imports unlike includes are
724 cached as imports are often used just as a module that holds macros.
726 This however can be changed of course explicitly. By adding `with context`
727 or `without context` to the import/include directive the current context
728 can be passed to the template and caching is disabled automatically.
732 {% from 'forms.html' import input with context %}
733 {% include 'header.html' without context %}
741 Jinja allows basic expressions everywhere. These work very similar to regular
742 Python and even if you're not working with Python you should feel comfortable
748 The simplest form of expressions are literals. Literals are representations
749 for Python objects such as strings and numbers. The following literals exist:
752 Everything between two double or single quotes is a string. They are
753 useful whenever you need a string in the template (for example as
754 arguments to function calls, filters or just to extend or include a
758 Integers and floating point numbers are created by just writing the
759 number down. If a dot is present the number is a float, otherwise an
760 integer. Keep in mind that for Python ``42`` and ``42.0`` is something
763 ['list', 'of', 'objects']:
764 Everything between two brackets is a list. Lists are useful to store
765 sequential data in or to iterate over them. For example you can easily
766 create a list of links using lists and tuples with a for loop::
769 {% for href, caption in [('index.html', 'Index'), ('about.html', 'About'),
770 ('downloads.html', 'Downloads')] %}
771 <li><a href="{{ href }}">{{ caption }}</a></li>
775 ('tuple', 'of', 'values'):
776 Tuples are like lists, just that you can't modify them. If the tuple
777 only has one item you have to end it with a comma. Tuples are usually
778 used to represent items of two or more elements. See the example above
781 {'dict': 'of', 'key': 'and', 'value': 'pairs'}:
782 A dict in Python is a structure that combines keys and values. Keys must
783 be unique and always have exactly one value. Dicts are rarely used in
784 templates, they are useful in some rare cases such as the :func:`xmlattr`
788 true is always true and false is always false. Keep in mind that those
789 literals are lowercase!
794 Jinja allows you to calculate with values. This is rarely useful in templates
795 but exists for completeness sake. The following operators are supported:
798 Adds two objects with each other. Usually numbers but if both objects are
799 strings or lists you can concatenate them this way. This however is not
800 the preferred way to concatenate strings! For string concatenation have
801 a look at the ``~`` operator. ``{{ 1 + 1 }}`` is ``2``.
804 Substract two numbers from each other. ``{{ 3 - 2 }}`` is ``1``.
807 Divide two numbers. The return value will be a floating point number.
808 ``{{ 1 / 2 }}`` is ``{{ 0.5 }}``.
811 Divide two numbers and return the truncated integer result.
812 ``{{ 20 / 7 }}`` is ``2``.
815 Calculate the remainder of an integer division between the left and right
816 operand. ``{{ 11 % 7 }}`` is ``4``.
819 Multiply the left operand with the right one. ``{{ 2 * 2 }}`` would
820 return ``4``. This can also be used to repeat string multiple times.
821 ``{{ '=' * 80 }}`` would print a bar of 80 equal signs.
824 Raise the left operand to the power of the right operand. ``{{ 2**3 }}``
830 For `if` statements / `for` filtering or `if` expressions it can be useful to
831 combine group multiple expressions:
834 Return true if the left and the right operand is true.
837 Return true if the left or the right operand is true.
840 negate a statement (see below).
845 Note that there is no support for any bit operations or something similar.
847 - special note regarding ``not``: The ``is`` and ``in`` operators support
848 negation using an infix notation too: ``foo is not bar`` and
849 ``foo not in bar`` instead of ``not foo is bar`` and ``not foo in bar``.
850 All other expressions require a prefix notation: ``not (foo and bar).``
856 The following operators are very useful but don't fit into any of the other
860 Perform sequence / mapping containment test. Returns true if the left
861 operand is contained in the right. ``{{ 1 in [1, 2, 3] }}`` would for
865 Performs a :ref:`test <tests>`.
868 Applies a :ref:`filter <filters>`.
871 Converts all operands into strings and concatenates them.
872 ``{{ "Hello " ~ name ~ "!" }}`` would return (assuming `name` is
873 ``'John'``) ``Hello John!``.
876 Call a callable: ``{{ post.render() }}``. Inside of the parentheses you
877 can use arguments and keyword arguments like in python:
878 ``{{ post.render(user, full=true) }}``.
881 Get an attribute of an object. (See :ref:`variables`)
889 It is also possible to use inline `if` expressions. These are useful in some
890 situations. For example you can use this to extend from one template if a
891 variable is defined, otherwise from the default layout template::
893 {% extends layout_template if layout_template is defined else 'master.html' %}
895 The general syntax is ``<do something> if <something is true> else <do
901 List of Builtin Filters
902 -----------------------
909 List of Builtin Tests
910 ---------------------
915 List of Global Functions
916 ------------------------
918 The following functions are available in the global scope by default:
920 .. function:: range([start,] stop[, step])
922 Return a list containing an arithmetic progression of integers.
923 range(i, j) returns [i, i+1, i+2, ..., j-1]; start (!) defaults to 0.
924 When step is given, it specifies the increment (or decrement).
925 For example, range(4) returns [0, 1, 2, 3]. The end point is omitted!
926 These are exactly the valid indices for a list of 4 elements.
928 This is useful to repeat a template block multiple times for example
929 to fill a list. Imagine you have 7 users in the list but you want to
930 render three empty items to enforce a height with CSS::
933 {% for user in users %}
934 <li>{{ user.username }}</li>
936 {% for number in range(10 - users|count) %}
937 <li class="empty"><span>...</span></li>
941 .. function:: lipsum(n=5, html=True, min=20, max=100)
943 Generates some lorem ipsum for the template. Per default five paragraphs
944 with HTML are generated each paragraph between 20 and 100 words. If html
945 is disabled regular text is returned. This is useful to generate simple
946 contents for layout testing.
948 .. function:: dict(\**items)
950 A convenient alternative to dict literals. ``{'foo': 'bar'}`` is the same
951 as ``dict(foo='bar')``.
957 The following sections cover the built-in Jinja2 extensions that may be
958 enabled by the application. The application could also provide further
959 extensions not covered by this documentation. In that case there should
960 be a separate document explaining the extensions.
962 .. _i18n-in-templates:
967 If the i18n extension is enabled it's possible to mark parts in the template
968 as translatable. To mark a section as translatable you can use `trans`::
970 <p>{% trans %}Hello {{ user }}!{% endtrans %}</p>
972 To translate a template expression --- say, using template filters or just
973 accessing an attribute of an object --- you need to bind the expression to a
974 name for use within the translation block::
976 <p>{% trans user=user.username %}Hello {{ user }}!{% endtrans %}</p>
978 If you need to bind more than one expression inside a `trans` tag, separate
979 the pieces with a comma (``,``)::
981 {% trans book_title=book.title, author=author.name %}
982 This is {{ book_title }} by {{ author }}
985 Inside trans tags no statements are allowed, only variable tags are.
987 To pluralize, specify both the singular and plural forms with the `pluralize`
988 tag, which appears between `trans` and `endtrans`::
990 {% trans count=list|length %}
991 There is {{ count }} {{ name }} object.
993 There are {{ count }} {{ name }} objects.
996 Per default the first variable in a block is used to determine the correct
997 singular or plural form. If that doesn't work out you can specify the name
998 which should be used for pluralizing by adding it as parameter to `pluralize`::
1000 {% trans ..., user_count=users|length %}...
1001 {% pluralize user_count %}...{% endtrans %}
1003 It's also possible to translate strings in expressions. For that purpose
1004 three functions exist:
1006 _ `gettext`: translate a single string
1007 - `ngettext`: translate a pluralizable string
1008 - `_`: alias for `gettext`
1010 For example you can print a translated string easily this way::
1012 {{ _('Hello World!') }}
1014 To use placeholders you can use the `format` filter::
1016 {{ _('Hello %(user)s!')|format(user=user.username) }}
1018 {{ _('Hello %s')|format(user.username) }}
1020 For multiple placeholders always use keyword arguments to `format` as other
1021 languages may not use the words in the same order.
projects / jinja2.git / blob