Configure your template strings

Last modified: August 22nd, 2025

What are template strings?#

Template strings are a mixture of literal text and dynamic placeholders that are replaced with data. You can use template strings to populate complex strings.

Template strings are commonly used in:

Please read these articles for more specific information about the best placeholders for each use case.

Placeholders#

Placeholders reference front matter or data values. When CloudCannon reads a placeholder, it will replace the content with the data it references.

There are two types of placeholders.

Data placeholder — Reads data you defined in your front matter or other data values. These placeholders use { } brackets.
Fixed placeholder — Reads fixed data defined by CloudCannon. These placeholders use [ ] brackets.

Filters#

Placeholders support several filters. Filters occur after the placeholder key, with a | character separating each key and filter. You can use multiple filters in sequence.

Generic filters#

uppercase transforms text to uppercase
lowercase transforms text to lowercase
deburr converts Latin-1 Supplement and Latin Extended-A letters to basic Latin letters and removes combining diacritical marks.
slugify converts non-alphanumeric characters into hyphens, then collapses sequential hyphens, then removes leading/trailing and hyphens.
trim removes leading and trailing whitespace

Date filters#

year gets a 4-digit year from a date
month gets a 2-digit month from a date
day gets a 4-digit day from a date
time gets the time from a date, in a 12-hour format (e.g. 12:30pm)
timezone gets the timezone from a date
date_short gets a short date format (e.g. 7/12/2022)
date_medium gets a medium date format (e.g. 7 Dec 2022)
date_long gets a long date format (e.g. 7 December 2022)
date_full gets a longer date format (e.g. Tuesday, 7 December 2022)
time gets the time (e.g. 1:00pm)
time_short gets a short time format (e.g. 1:00 pm)
time_medium gets a medium time format (e.g. 1:00:00 pm)
time_long gets a long time format (e.g. 1:00:00 pm NZDT)
time_full gets a longer time format (e.g. 1:00:00 pm New Zealand Daylight Time)

All the time and date filters format the date using the site's timezone and the user's locale.

Filters with parameters#

For some filters, you can provide extra parameters for more flexibility. Add extra parameters by including a = character after the filter name.

truncate removes any extra characters beyond a specified number. For example, {title|truncate=10} will resolve to the first 10 characters of a message.
default allows you to provide a fallback value, in case the data is empty
if resolves to the data, if the parameter is "truthy"
unless resolves to the data, if the parameter is "falsy"
substring extracts a section of a string, using the JavaScript substring method. You can specify a start and end index separated by a comma. For example, {title|substring=1} resolves to every character after the first. {title|substring=1,2} resolves to the 1 character only.
strip_leading_date removes a date from the start of a string (or after a single /). The date can be any string composed of three numbers, where one number is 4 digits long and the other two are 1 or 2 digits, and which are separated by dashes, underscores, periods, or commas. For example "/2025-12-01-blog.md"|strip_leading_date will resolve to /blog.md.

Filtering examples#

Let's go through some examples for the following file:

short-message.mdx

copied


date: 2020-01-02
empty_value:
message: "Hello World"
draft: false

In the above file we have four keys containing different data types: date, empty_value, message, and draft.

Here are some examples of how we can transform this data using different filters:

copied


{date|day}-{date|month}-{date|year} {date|time} ({date|timezone}) 
// 01-02-2020 00:00am (Etc/UTC)

{message|uppercase|truncate=5} 
// HELLO

{message|if=message} 
// Hello World

{message|unless=empty_value} 
// Hello World

{empty_value|default="Nothing here!"} 
// Nothing here!

{"Unpublished"|if=draft|default="Published"} 
// Published

We can use multiple date filters to control the output string. This template string uses dynamic data placeholders and literal text characters, such as - and ().

We can convert text strings to uppercase and truncate the number of characters to five.

We can print the value of a key if a value exists using the if filter.

We can print the value of a key based on the value of another key using the unless filter. In this case, we print the value of message because empty_value is falsy.

We can create a fallback option when a placeholder resolves to an empty result using the default filter. In this case, "Nothing here!" is printed because empty_value contains no value.

We can use multiple filters to check if a key contains a value and create a fallback string if that key is falsy.

Filtering nested keys and arrays#

Data placeholders can reference nested keys in your front matter or other data values.

Here is an example file:

copied


links:
  - url: /documentation
    text: Learn more
  - url: /blog
    text: Read more
  - url:
    text:
seo:
  description: Description goes here
  tags:
    - 'sales'
    - 'documentation'

In the above file, we have several nested keys and arrays. You can reference these keys in a template string by using the relative path of the key, by specifying the position within an array, or by searching each item in an array using [*].

Here are some examples of how we can transform this data using different filters:

When you use [*] to reference each item within an array, CloudCannon will join the final output into a single string, separating each value with a comma and a space.

copied


{seo.description} 
// Description goes here

{links.text[0].description} 
// Learn more

{seo.tags[*]|uppercase} 
// SALES, DOCUMENTATION

{links[*].text|default="No text"} 
// Learn more, Read more, No text

We can print the value of a nested key.

We can print the value of a specific key within an array.

We can print the value of every item within an array and filter the result with uppercase. CloudCannon automatically joins the final output into a single string.

We can search an array using and print the value of a key each time it appears in that array. If one key is empty, we can use a fallback value using the default filter.