Template context variables and filters

Variables

debug

Invoke pdb breakpoint from a template.

Example:

<h1>{{ site_name }}</h1>

{{ debug() }}

This will invoke function from websauna.template_debugger setting. The debugger is turned on only on development.ini. If there is no debugger configured, a warning is given.

See websauna.system.core.vars.debug() for more information.

js_in_head

Should <script> tags be placed in <head> or end of <body>.

See websauna.system.core.vars.js_in_head() for more information.

now

Get the current time as UTC.

websauna.utils.time.now() function.

Example:

See websauna.system.core.vars._now() for more information.

on_demand_resource_renderer

Active instance of websauna.system.core.render.OnDemandResourceRenderer managing dynamic CSS and JS. May be None.

See websauna.system.core.vars.on_demand_resource_renderer() for more information.

site_author

Expose website URL from websauna.site_author config variable to templates.

This is used in footer to display the site owner.

See websauna.system.core.vars.site_author() for more information.

site_email_prefix

Expose website URL from websauna.site_email_prefix config variable to templates.

This is used as the subject prefix in outgoing email. E.g. if the value is SuperSite you’ll email subjects:

[SuperSite] Welcome to www.supersite.com

See websauna.system.core.vars.site_email_prefix() for more information.

site_name

Expose website name from websauna.site_name config variable to templates.

Example:

<div class="jumbotron text-center">
    <h1>{{ site_name }}</h1>
    <p class="lead text-center">
        {{ site_tag_line }}
    </p>
</div>

See websauna.system.core.vars.site_name() for more information.

site_tag_line

Expose website URL from websauna.site_tag_line config variable to templates.

This is used on the default front page to catch the attention of audience.

See websauna.system.core.vars.site_tag_line() for more information.

site_time_zone

Expose website URL from websauna.site_time_zone config variable to templates.

By best practices, all dates and times should be stored in the database using UTC time. This setting allows quickly convert dates and times to your local time.

Example:

<p>
    <strong>Bar opens</strong>:
    {{ opening_at|friendly_time(timezone=site_time_zone) }}
</p>

Default value is UTC.

See timezone abbreviation list.

See websauna.system.core.vars.site_time_zone() for more information.

site_title

Expose website name from websauna.site_title config variable to templates.

This is the default <title> tag.

Example:

<meta>
    <title>My page - {{ site_title }}</title>
</meta>

See websauna.system.core.vars.site_title() for more information.

site_url

Expose website URL from websauna.site_url config variable to templates.

Note

You should not use this variable in web page templates. This variable is intended for cases where one needs templating without running a web server.

The correct way to get the home URL of your website is:

<a href="{{ request.route_url('home') }}">Home</a>

See websauna.system.core.vars.site_url() for more information.

timedelta

Expose Python timedelta class to templates, so you can do relative time calculations.

For more information see datetime.timedelta.

Example:

See websauna.system.core.vars._timedelta() for more information.

Filters

abs

Return the absolute value of the argument.

See abs() for more information.

admin_breadcrumbs

Render admin interface top breadcrumbs bar.

See websauna.system.admin.filters.admin_breadcrumbs() for more information.

admin_url

Link to model in admin interface.

Takes an SQLAlchemy model instance as a filter argument and resolves its admin page. This requires that a model admin has been correctly registered for SQLAlchemy model.

Example:

{% if request.user and request.user.is_admin %}
    <li>
      <a class="btn btn-danger" href="{{ choice|admin_url("edit") }}">
        Edit in admin
      </a>
    </li>
{% endif %}

Another example:

<li>
  <a class="btn btn-danger" href="{{ choice|admin_url }}">
    View in admin
  </a>
</li>

See websauna.system.core.templatecontext.admin_url() for more information.

arrow_format

Format datetime using Arrow formatter string.

Context must be a time/datetime object.

Arrow is a Python helper library for parsing and formatting datetimes.

Example:

<li>
  Offer created at {{ offer.created_at|arrow_format('YYYYMMDDHHMMss') }}
</li>

See Arrow formatting.

See websauna.system.core.templatecontext.arrow_format() for more information.

attr

Get an attribute of an object. foo|attr("bar") works like foo.bar just that always an attribute is returned and items are not looked up.

See Notes on subscriptions for more details.

batch

A filter that batches items. It works pretty much like slice just the other way round. It returns a list of lists with the given number of items. If you provide a second parameter this is used to fill up missing items. See this example:

<table>
{%- for row in items|batch(3, '&nbsp;') %}
  <tr>
  {%- for column in row %}
    <td>{{ column }}</td>
  {%- endfor %}
  </tr>
{%- endfor %}
</table>

capitalize

Capitalize a value. The first character will be uppercase, all others lowercase.

center

Centers the value in a field of a given width.

count

Return the number of items in a container.

See len() for more information.

d

If the value is undefined it will return the passed default value, otherwise the value of the variable:

{{ my_variable|default('my_variable is not defined') }}

This will output the value of my_variable if the variable was defined, otherwise 'my_variable is not defined'. If you want to use default with variables that evaluate to false you have to set the second parameter to true:

{{ ''|default('the string was empty', true) }}

datetime

Format datetime in a certain timezone.

See websauna.system.core.templatecontext.filter_datetime() for more information.

default

If the value is undefined it will return the passed default value, otherwise the value of the variable:

{{ my_variable|default('my_variable is not defined') }}

This will output the value of my_variable if the variable was defined, otherwise 'my_variable is not defined'. If you want to use default with variables that evaluate to false you have to set the second parameter to true:

{{ ''|default('the string was empty', true) }}

dictsort

Sort a dict and yield (key, value) pairs. Because python dicts are unsorted you may want to use this function to order them by either key or value:

{% for item in mydict|dictsort %}
    sort the dict by key, case insensitive

{% for item in mydict|dictsort(reverse=true) %}
    sort the dict by key, case insensitive, reverse order

{% for item in mydict|dictsort(true) %}
    sort the dict by key, case sensitive

{% for item in mydict|dictsort(false, 'value') %}
    sort the dict by value, case insensitive

e

escape(s) -> markup

Convert the characters &, <, >, ‘, and ” in string s to HTML-safe sequences. Use this if you need to display text that might contain such characters in HTML. Marks return value as markup string.

See markupsafe._speedups.escape() for more information.

escape

escape(s) -> markup

Convert the characters &, <, >, ‘, and ” in string s to HTML-safe sequences. Use this if you need to display text that might contain such characters in HTML. Marks return value as markup string.

See markupsafe._speedups.escape() for more information.

escape_js

Make JSON strings to safe to be embedded inside <script> tag.

See websauna.system.core.templatecontext.escape_js() for more information.

filesizeformat

Format the value like a ‘human-readable’ file size (i.e. 13 kB, 4.1 MB, 102 Bytes, etc). Per default decimal prefixes are used (Mega, Giga, etc.), if the second parameter is set to True the binary prefixes are used (Mebi, Gibi).

first

Return the first item of a sequence.

float

Convert the value into a floating point number. If the conversion doesn’t work it will return 0.0. You can override this default using the first parameter.

forceescape

Enforce HTML escaping. This will probably double escape variables.

format

Apply python string formatting on an object:

{{ "%s - %s"|format("Hello?", "Foo!") }}
    -> Hello? - Foo!

friendly_time

Format timestamp in human readable format.

  • Context must be a datetimeobject
  • Takes optional keyword argument timezone which is a timezone name as a string. Assume the source datetime is in this timezone.

See websauna.system.core.templatecontext.friendly_time() for more information.

from_timestamp

Convert UNIX datetime to timestamp.

Example:

<p>
    Prestodoctor license expires: {{ prestodoctor.recommendation.expires|from_timestamp(timezone="US/Pacific")|friendly_time }}
</p>
param context:UNIX timestamps as float as seconds since 1970
return:Python datetime object

See websauna.system.core.templatecontext.from_timestamp() for more information.

groupby

Group a sequence of objects by a common attribute.

If you for example have a list of dicts or objects that represent persons with gender, first_name and last_name attributes and you want to group all users by genders you can do something like the following snippet:

<ul>
{% for group in persons|groupby('gender') %}
    <li>{{ group.grouper }}<ul>
    {% for person in group.list %}
        <li>{{ person.first_name }} {{ person.last_name }}</li>
    {% endfor %}</ul></li>
{% endfor %}
</ul>

Additionally it’s possible to use tuple unpacking for the grouper and list:

<ul>
{% for grouper, list in persons|groupby('gender') %}
    ...
{% endfor %}
</ul>

As you can see the item we’re grouping by is stored in the grouper attribute and the list contains all the objects that have this grouper in common.

Changed in version 2.6: It’s now possible to use dotted notation to group by the child attribute of another attribute.

indent

Return a copy of the string with each line indented by 4 spaces. The first line and blank lines are not indented by default.

param width:Number of spaces to indent by.
param first:Don’t skip indenting the first line.
param blank:Don’t skip indenting empty lines.

Changed in version 2.10: Blank lines are not indented by default.

Rename the indentfirst argument to first.

int

Convert the value into an integer. If the conversion doesn’t work it will return 0. You can override this default using the first parameter. You can also override the default base (10) in the second parameter, which handles input with prefixes such as 0b, 0o and 0x for bases 2, 8 and 16 respectively. The base is ignored for decimal numbers and non-string values.

join

Return a string which is the concatenation of the strings in the sequence. The separator between elements is an empty string per default, you can define it with the optional parameter:

{{ [1, 2, 3]|join('|') }}
    -> 1|2|3

{{ [1, 2, 3]|join }}
    -> 123

It is also possible to join certain attributes of an object:

{{ users|join(', ', attribute='username') }}

New in version 2.6: The attribute parameter was added.

last

Return the last item of a sequence.

length

Return the number of items in a container.

See len() for more information.

list

Convert the value into a list. If it was a string the returned list will be a list of characters.

lower

Convert a value to lowercase.

map

Applies a filter on a sequence of objects or looks up an attribute. This is useful when dealing with lists of objects but you are really only interested in a certain value of it.

The basic usage is mapping on an attribute. Imagine you have a list of users but you are only interested in a list of usernames:

Users on this page: {{ users|map(attribute='username')|join(', ') }}

Alternatively you can let it invoke a filter by passing the name of the filter and the arguments afterwards. A good example would be applying a text conversion filter on a sequence:

Users on this page: {{ titles|map('lower')|join(', ') }}

New in version 2.7.

max

Return the largest item from the sequence.

{{ [1, 2, 3]|max }}
    -> 3
param case_sensitive:
 Treat upper and lower case strings as distinct.
param attribute:
 Get the object with the max value of this attribute.

min

Return the smallest item from the sequence.

{{ [1, 2, 3]|min }}
    -> 1
param case_sensitive:
 Treat upper and lower case strings as distinct.
param attribute:
 Get the object with the max value of this attribute.

model_url

A filter from model to a string representing the absolute URL. This filter calls pyramid.url.resource_url().

Note

This is being deprecated. See pyramid_jinja2.filters.resource_url()

See pyramid_jinja2.filters.model_url_filter() for more information.

pprint

Pretty print a variable. Useful for debugging.

With Jinja 1.2 onwards you can pass it a parameter. If this parameter is truthy the output will be more verbose (this requires pretty)

random

Return a random item from the sequence.

reject

Filters a sequence of objects by applying a test to each object, and rejecting the objects with the test succeeding.

If no test is specified, each object will be evaluated as a boolean.

Example usage:

{{ numbers|reject("odd") }}

New in version 2.7.

rejectattr

Filters a sequence of objects by applying a test to the specified attribute of each object, and rejecting the objects with the test succeeding.

If no test is specified, the attribute’s value will be evaluated as a boolean.

{{ users|rejectattr("is_active") }}
{{ users|rejectattr("email", "none") }}

New in version 2.7.

render_panel

Render a panel inline in a template.

Allows placing admin panels in templates directly.

Example how to include panel at the top of admin CRUD listing template:

{% block title %}

  <h1>{{title}}</h1>

  {{ context|render_panel(name="admin_panel", controls=False) }}

{% endblock %}
param context:Any resource object, like ModelAdmin instance
param name:registered panel name, like admin_panel
param kwargs:Passed to the panel function as is
return:HTML string of the rendered panel

See websauna.system.core.templatecontext.render_panel() for more information.

replace

Return a copy of the value with all occurrences of a substring replaced with a new one. The first argument is the substring that should be replaced, the second is the replacement string. If the optional third argument count is given, only the first count occurrences are replaced:

{{ "Hello World"|replace("Hello", "Goodbye") }}
    -> Goodbye World

{{ "aaaaargh"|replace("a", "d'oh, ", 2) }}
    -> d'oh, d'oh, aaargh

reverse

Reverse the object or return an iterator that iterates over it the other way round.

round

Round the number to a given precision. The first parameter specifies the precision (default is 0), the second the rounding method:

  • 'common' rounds either up or down
  • 'ceil' always rounds up
  • 'floor' always rounds down

If you don’t specify a method 'common' is used.

{{ 42.55|round }}
    -> 43.0
{{ 42.55|round(1, 'floor') }}
    -> 42.5

Note that even if rounded to 0 precision, a float is returned. If you need a real integer, pipe it through int:

{{ 42.55|round|int }}
    -> 43

route_url

A filter from route_name to a string representing the absolute URL. This filter calls pyramid.url.route_url().

Example:

<a href="{{'login'|route_url}}">
    Sign in
</a>

See pyramid_jinja2.filters.route_url_filter() for more information.

safe

Mark the value as safe which means that in an environment with automatic escaping enabled this variable will not be escaped.

select

Filters a sequence of objects by applying a test to each object, and only selecting the objects with the test succeeding.

If no test is specified, each object will be evaluated as a boolean.

Example usage:

{{ numbers|select("odd") }}
{{ numbers|select("odd") }}
{{ numbers|select("divisibleby", 3) }}
{{ numbers|select("lessthan", 42) }}
{{ strings|select("equalto", "mystring") }}

New in version 2.7.

selectattr

Filters a sequence of objects by applying a test to the specified attribute of each object, and only selecting the objects with the test succeeding.

If no test is specified, the attribute’s value will be evaluated as a boolean.

Example usage:

{{ users|selectattr("is_active") }}
{{ users|selectattr("email", "none") }}

New in version 2.7.

slice

Slice an iterator and return a list of lists containing those items. Useful if you want to create a div containing three ul tags that represent columns:

<div class="columwrapper">
  {%- for column in items|slice(3) %}
    <ul class="column-{{ loop.index }}">
    {%- for item in column %}
      <li>{{ item }}</li>
    {%- endfor %}
    </ul>
  {%- endfor %}
</div>

If you pass it a second argument it’s used to fill missing values on the last iteration.

sort

Sort an iterable. Per default it sorts ascending, if you pass it true as first argument it will reverse the sorting.

If the iterable is made of strings the third parameter can be used to control the case sensitiveness of the comparison which is disabled by default.

{% for item in iterable|sort %}
    ...
{% endfor %}

It is also possible to sort by an attribute (for example to sort by the date of an object) by specifying the attribute parameter:

{% for item in iterable|sort(attribute='date') %}
    ...
{% endfor %}

Changed in version 2.6: The attribute parameter was added.

static_url

A filter from path to a string representing the absolute URL. This filter calls pyramid.url.static_url().

Example:

<link rel="stylesheet" href="{{'yourapp:static/css/style.css'|static_url}}" />

See pyramid_jinja2.filters.static_url_filter() for more information.

string

soft_unicode(object) -> string

Make a string unicode if it isn’t already. That way a markup string is not converted back to unicode.

See markupsafe._speedups.soft_unicode() for more information.

striptags

Strip SGML/XML tags and replace adjacent whitespace by one space.

sum

Returns the sum of a sequence of numbers plus the value of parameter ‘start’ (which defaults to 0). When the sequence is empty it returns start.

It is also possible to sum up only certain attributes:

Total: {{ items|sum(attribute='price') }}

Changed in version 2.6: The attribute parameter was added to allow suming up over attributes. Also the start parameter was moved on to the right.

timestruct

Render both humanized time and accurate time.

  • show_timezone
  • target_timezone
  • source_timezone
  • format

See websauna.system.core.templatecontext.timestruct() for more information.

title

Return a titlecased version of the value. I.e. words will start with uppercase letters, all remaining characters are lowercase.

to_json

Converts Python dict to JSON, safe to be placed inside <script> tag.

Example:

{#
  Export server side generated graph data points
  to Rickshaw client side graph rendering
#}
{% if graph_data %}
  <script>
    window.graphDataJSON = "{{ graph_data|to_json }}";
  </script>
{% endif %}
param context:Takes Python dictionary as input
param safe:Set to False to not to run escape_js() on the resulting JSON. True by default.
return:JSON string to be included inside HTML code

See websauna.system.core.templatecontext.to_json() for more information.

tojson

Dumps a structure to JSON so that it’s safe to use in <script> tags. It accepts the same arguments and returns a JSON string. Note that this is available in templates through the |tojson filter which will also mark the result as safe. Due to how this function escapes certain characters this is safe even if used outside of <script> tags.

The following characters are escaped in strings:

  • <
  • >
  • &
  • '

This makes it safe to embed such strings in any place in HTML with the notable exception of double quoted attributes. In that case single quote your attributes or HTML escape it in addition.

The indent parameter can be used to enable pretty printing. Set it to the number of spaces that the structures should be indented with.

Note that this filter is for use in HTML contexts only.

New in version 2.9.

trim

Strip leading and trailing whitespace.

truncate

Return a truncated copy of the string. The length is specified with the first parameter which defaults to 255. If the second parameter is true the filter will cut the text at length. Otherwise it will discard the last word. If the text was in fact truncated it will append an ellipsis sign ("..."). If you want a different ellipsis sign than "..." you can specify it using the third parameter. Strings that only exceed the length by the tolerance margin given in the fourth parameter will not be truncated.

{{ "foo bar baz qux"|truncate(9) }}
    -> "foo..."
{{ "foo bar baz qux"|truncate(9, True) }}
    -> "foo ba..."
{{ "foo bar baz qux"|truncate(11) }}
    -> "foo bar baz qux"
{{ "foo bar baz qux"|truncate(11, False, '...', 0) }}
    -> "foo bar..."

The default leeway on newer Jinja2 versions is 5 and was 0 before but can be reconfigured globally.

unique

Returns a list of unique items from the the given iterable.

{{ ['foo', 'bar', 'foobar', 'FooBar']|unique }}
    -> ['foo', 'bar', 'foobar']

The unique items are yielded in the same order as their first occurrence in the iterable passed to the filter.

param case_sensitive:
 Treat upper and lower case strings as distinct.
param attribute:
 Filter objects with unique values for this attribute.

upper

Convert a value to uppercase.

urlencode

Escape strings for use in URLs (uses UTF-8 encoding). It accepts both dictionaries and regular strings as well as pairwise iterables.

New in version 2.7.

urlize

Converts URLs in plain text into clickable links.

If you pass the filter an additional integer it will shorten the urls to that number. Also a third argument exists that makes the urls “nofollow”:

{{ mytext|urlize(40, true) }}
    links are shortened to 40 chars and defined with rel="nofollow"

If target is specified, the target attribute will be added to the <a> tag:

{{ mytext|urlize(40, target='_blank') }}

Changed in version 2.8+: The target parameter was added.

uuid_to_slug

Convert UUID object to a base64 encoded slug.

Example:

{% for question in latest_question_list %}
    <li>
      <a href="{{ route_url('details', question.uuid|uuid_to_slug) }}">
        {{ question.question_text }}
      </a>
    </li>
{% endfor %}

See websauna.system.core.templatecontext.uuid_to_slug() for more information.

wordcount

Count the words in that string.

wordwrap

Return a copy of the string passed to the filter wrapped after 79 characters. You can override this default using the first parameter. If you set the second parameter to false Jinja will not split words apart if they are longer than width. By default, the newlines will be the default newlines for the environment, but this can be changed using the wrapstring keyword argument.

New in version 2.7: Added support for the wrapstring parameter.

xmlattr

Create an SGML/XML attribute string based on the items in a dict. All values that are neither none nor undefined are automatically escaped:

<ul{{ {'class': 'my_list', 'missing': none,
        'id': 'list-%d'|format(variable)}|xmlattr }}>
...
</ul>

Results in something like this:

<ul class="my_list" id="list-42">
...
</ul>

As you can see it automatically prepends a space in front of the item if the filter returned something unless the second parameter is false.