Filters

A filter changes a value as it is written into a document. Put it after the value with |, and give it any values it needs in brackets:

{{ form.DraftFormName|upper }}
{{ form.als_fields_set.count() }} field{{ form.als_fields_set.count()|pluralize }}

Filters can follow one another, each working on what the one before it gave. To apply a filter to a whole block of a template rather than one value, use {% filter %}:

{% filter upper %}
This text is written in capitals.
{% endfilter %}

This page lists every filter a Document Template can use. Any other filter name stops the template with an error.

The examples use three values a real template would get from its data: when, a date and time of 5 March 2026 14:30 UTC; forms, three Forms with OIDs DM, AE and VS, of which AE is inactive; and form, the first of them. The Gives column is exactly what each example writes into the document.

Values are escaped

Text written into a document has &, <, > and quotes replaced by their escaped forms, so a value cannot break the document's markup. This is why Fish & Chips is written as Fish & Chips. Filters that produce markup on purpose, such as markdown and clean_html, mark their result as safe so it is not escaped a second time.

This happens in every type of Template, Text included. A Text Template that writes plain text, Markdown or CSV rather than XML should write its values with safe, as in {{ form.DraftFormName|safe }}, so that they appear exactly as they are stored.

Two things are not escaped. The text the {% ai %} tag writes is used exactly as it comes back, and The AI tag lists the filters to use on it. The result of a {% filter %} block is not escaped again either, but the values inside it already were, so a filter that changes letters can break them: {% filter upper %}{{ "Fish & Chips" }}{% endfilter %} writes FISH & CHIPS. Apply such a filter to the value instead: {{ "Fish & Chips"|upper }}.

Filters added by TrialGrid

Filter	What it does	Example	Gives
chunk	Splits a list into lists of the length you give. The last one holds what is left.	{% for row in [1, 2, 3, 4, 5]|chunk(2) %}[{{ row|join(" ") }}] {% endfor %}	[1 2] [3 4] [5]
clean_html	Keeps only the HTML tags you list and removes the others, keeping their text. With no list, keeps a standard set of text formatting tags. On a Word, Excel or PDF Template, follow it with convert_html.	{{ "<p>Hello <span>there</span></p>"|clean_html(["p"]) }}	<p>Hello there</p>
convert_html	Turns HTML into Word or Excel formatting, so bold, lists and paragraphs appear as they would on a web page. Only in Word and Excel Templates.
date	Writes a date and time as year, month and day. Gives nothing for an empty value.	{{ when|date }}	2026-03-05
format_datetime	Writes a date and time in the format you give, using the codes in Python Date Formats. Gives nothing for an empty value.	{{ when|format_datetime("%d %b %Y %H:%M") }}	05 Mar 2026 14:30
html_sanitize	Removes HTML tags and attributes that are not on a fixed list of safe formatting, keeping their text.	{{ "<b>Bold</b><script>x()</script>"|html_sanitize }}	<b>Bold</b>x()
iso	Writes a date and time in the ISO 8601 format. Gives nothing for an empty value.	{{ when|iso }}	2026-03-05T14:30:00+00:00
line_breaks_br	Escapes the text, then turns each line break into <br/>. On a Word or Excel Template, follow it with convert_html.	{{ "one\ntwo"|line_breaks_br }}	one<br/>two
markdown	Turns Markdown into HTML. Any HTML already in the text is removed first. On a Word or Excel Template, follow it with convert_html.	{{ "Some **bold** text"|markdown }}	<p>Some <strong>bold</strong> text</p>
normalize_decimal	Writes a decimal number without trailing zeros or scientific notation. Any other value is written as it is.	{{ 2.50|normalize_decimal }}	2.5
pluralize	Applied to a number, gives s unless the number is 1, for adding to a word. For other endings, give the singular and plural ending separated by a comma.	3 Form{{ 3|pluralize }}, 1 Form{{ 1|pluralize }}, 2 Entr{{ 2|pluralize("y,ies") }}	3 Forms, 1 Form, 2 Entries
remove_line_break	Joins the lines of a text into one line, with a space between each. HTML in the text is escaped, so it is shown rather than used.	{{ "one\ntwo"|remove_line_break }}	one two
rml_sanitize	Turns HTML into the markup a PDF Template's paragraphs accept. Links are removed and their text kept, unless you pass True.	{{ "<p>See <a href='https://example.com'>this</a></p>"|rml_sanitize }}	See this
safe_json	Marks JSON text as safe to place inside a <script> block, replacing <, > and & with their JSON escapes.	{{ '{"a": "<b>"}'|safe_json }}	{"a": "\u003cb\u003e"}
slugify	Turns text into lowercase letters, numbers and hyphens, suitable for a file name or an anchor.	{{ "Adverse Events (AE)"|slugify }}	adverse-events-ae
strip_tags	Removes HTML tags, leaving their text.	{{ "<p>Hello <b>there</b></p>"|strip_tags }}	Hello there
timezone	Converts a date and time to the time zone you name. See List of Time Zones.	{{ when|timezone("America/New_York")|format_datetime("%H:%M") }}	09:30
utc	Writes a date and time with the name of its time zone. It does not convert the time: use timezone first for that.	{{ when|utc }}	2026-03-05 14:30:00 UTC
xml_escape	Escapes &, <, > and quotes, so text cannot break the markup of a PDF, Word or Excel Template.	{{ "Fish & Chips <hot>"|xml_escape }}	Fish &amp; Chips &lt;hot&gt;

convert_html has no example because what it gives is Word or Excel markup. See Generating Word Documents and Generating Excel Documents.

Filters from Jinja

These come with Jinja, the template language Document Templates are written in. The Jinja documentation describes each one in more depth.

Filter	What it does	Example	Gives
abs	The number without its sign.	{{ -3|abs }}	3
attr	An attribute of an object, by name.	{{ form|attr("OID") }}	DM
batch	Splits a list into lists of the length you give. A second value fills out the last one.	{% for row in [1, 2, 3]|batch(2, 0) %}[{{ row|join(" ") }}] {% endfor %}	[1 2] [3 0]
capitalize	The first letter upper case and the rest lower case.	{{ "adverse EVENTS"|capitalize }}	Adverse events
center	The text centred in the width you give.	[{{ "AE"|center(6) }}]	[  AE  ]
count	Another name for length.	{{ [1, 2, 3]|count }}	3
d	Another name for default.	{{ missing|d("none") }}	none
default	The value you give if the value is undefined. Pass true as a second value to use it for empty values as well.	{{ ""|default("none", true) }}	none
dictsort	The items of a dictionary sorted by key, or by value with by="value".	{% for k, v in {"b": 2, "a": 1}|dictsort %}{{ k }}={{ v }} {% endfor %}	a=1 b=2
e	Another name for escape.	{{ "<b>"|e }}	&lt;b&gt;
escape	Escapes &, <, > and quotes for HTML.	{{ "Fish & Chips"|escape }}	Fish &amp; Chips
filesizeformat	A number of bytes as a readable size.	{{ 1500000|filesizeformat }}	1.5 MB
first	The first item.	{{ ["DM", "AE"]|first }}	DM
float	The value as a decimal number.	{{ "2.5"|float + 1 }}	3.5
forceescape	Escapes for HTML even a value already marked safe.	{{ "<b>"|forceescape }}	&lt;b&gt;
format	Fills a printf-style pattern with the values you give.	{{ "%s has %d fields"|format("DM", 3) }}	DM has 3 fields
groupby	Groups a list of objects by an attribute. Each group has a grouper and its list.	{% for g in forms|groupby("DraftFormActive") %}{{ g.grouper }}: {{ g.list|map(attribute="OID")|join(", ") }}; {% endfor %}	False: AE; True: DM, VS;
indent	Indents every line but the first by the number of spaces you give. The example shows its line break as /.	{{ "a\nb"|indent(2)|replace("\n", "/") }}	a/  b
int	The value as a whole number.	{{ "42"|int + 1 }}	43
items	The key and value pairs of a dictionary, for a loop.	{% for k, v in {"a": 1}|items %}{{ k }}={{ v }}{% endfor %}	a=1
join	The items of a list joined with the text you give. attribute= joins one attribute of each.	{{ ["DM", "AE"]|join(", ") }}	DM, AE
last	The last item.	{{ ["DM", "AE"]|last }}	AE
length	How many items, or how many characters in a text. On a set of objects, use .count() instead, which does not read them.	{{ ["DM", "AE"]|length }}	2
list	The value as a list.	{{ "abc"|list|join("-") }}	a-b-c
lower	The text in lower case.	{{ "DM"|lower }}	dm
map	One attribute of each object (attribute=), or a filter applied to each item.	{{ forms|map(attribute="OID")|join(", ") }}	DM, AE, VS
max	The largest item. attribute= compares one attribute of each.	{{ [3, 7, 5]|max }}	7
min	The smallest item. attribute= compares one attribute of each.	{{ [3, 7, 5]|min }}	3
pprint	The value laid out for reading, for checking what a value holds.	{{ [1, 2]|pprint }}	[1, 2]
random	An item chosen at random.
reject	The items that fail a test.	{{ [1, 2, 3, 4]|reject("odd")|join(", ") }}	2, 4
rejectattr	The objects whose attribute fails a test, or is false if you name no test.	{{ forms|rejectattr("DraftFormActive")|map(attribute="OID")|join(", ") }}	AE
replace	The text with every occurrence of one piece replaced by another.	{{ "AE_FORM"|replace("_", " ") }}	AE FORM
reverse	The items, or the characters of a text, in the opposite order.	{{ ["DM", "AE"]|reverse|join(", ") }}	AE, DM
round	The number rounded to the places you give. method='floor' or method='ceil' rounds down or up.	{{ 2.567|round(1) }}	2.6
safe	Marks a value as safe, so it is not escaped. Use it on a value you know cannot break the document's markup, or in a Text Template whose output is not markup.	{{ "<b>bold</b>"|safe }}	<b>bold</b>
select	The items that pass a test.	{{ [1, 2, 3, 4]|select("odd")|join(", ") }}	1, 3
selectattr	The objects whose attribute passes a test, or is true if you name no test.	{{ forms|selectattr("DraftFormActive")|map(attribute="OID")|join(", ") }}	DM, VS
slice	Splits a list into the number of columns you give.	{% for column in [1, 2, 3, 4, 5]|slice(2) %}[{{ column|join(" ") }}] {% endfor %}	[1 2 3] [4 5]
sort	The items in order. reverse=true for largest first, attribute= to sort objects by one of their attributes.	{{ [3, 1, 2]|sort(reverse=true)|join(", ") }}	3, 2, 1
string	The value as text.	{{ (1)|string + "st" }}	1st
striptags	Removes HTML tags and runs of spaces.	{{ "<p>Hello  <b>there</b></p>"|striptags }}	Hello there
sum	The items added up. attribute= adds one attribute of each.	{{ [1, 2, 3]|sum }}	6
title	Each word starting with a capital letter.	{{ "adverse events"|title }}	Adverse Events
tojson	The value as JSON, safe to place inside a <script> block.	{{ {"a": [1, 2]}|tojson }}	{"a": [1, 2]}
trim	The text without spaces at the start and end.	[{{ "  AE  "|trim }}]	[AE]
truncate	The text cut to the length you give, ending in ....	{{ "Adverse Events Log"|truncate(12, killwords=true) }}	Adverse E...
unique	The items without duplicates.	{{ ["CheckBox", "Text", "CheckBox"]|unique|join(", ") }}	CheckBox, Text
upper	The text in upper case.	{{ "dm"|upper }}	DM
urlencode	The text encoded for use in a web address.	{{ "a b&c"|urlencode }}	a%20b%26c
urlize	Turns web addresses in a text into HTML links. On a Word or Excel Template, follow it with convert_html.	{{ "See https://example.com"|urlize }}	See <a href="https://example.com" rel="noopener">https://example.com</a>
wordcount	How many words in a text.	{{ "Adverse Events Log"|wordcount }}	3
wordwrap	Wraps a text at the width you give, with a line break or the wrapstring you give.	{{ "Adverse Events Log"|wordwrap(10, wrapstring=" / ") }}	Adverse / Events Log
xmlattr	Turns a dictionary into HTML or XML attributes.	<td{{ {"class": "oid"}|xmlattr }}>	<td class="oid">

random has no example because what it gives changes every time.