Template Syntax

Web templates are Mustache, the same syntax as mail templates and page templates, with the platform's additions: {{name}} writes a value, {{if}} and {{for}} decide and repeat, and {{price | money "EUR"}} formats. A template that does not compile is an error the block reports, not an empty page.

Values are escaped unless you ask otherwise

A name is looked up from the innermost context outward, the Mustache way, so inside a section the outer values are still visible. Numbers print without a needless .0, and a list or object prints as JSON. Changing the delimiters with {{=...=}} is not supported.

Conditions compare and combine

{{if status == 'paid'}}
  <span class="ok">Paid</span>
{{else if status == 'open' && total > 0}}
  <span class="warn">Open</span>
{{else}}
  <span>Nothing to pay</span>
{{/if}}

• Operators: == != > < >= <=, combined with &&, || and !.
• Literals: 'text', "text", numbers, true, false and null.
• Filters work in a condition: {{if items | length > 3}}.
• Closing: {{/if}}, {{end}}, or the name for a single value, as in {{if user}} ... {{/user}}. {{elseif c}} is the same as {{else if c}}.
• A comparison section also works: {{#n == 2}} ... {{/n == 2}}, and {{^n == 2}} for its opposite.

A bare value counts as false when it is missing, null, false, 0, an empty text or an empty list. Anything else counts as true, including an empty object and the text "0".

Numbers compare as numbers, also when one side is a text that holds a number, so {{if qty > 3}} works on a form field. Two texts compare as text, so "10" > "9" is false: compare with a number when you mean a number.

Loops repeat, and know where they are

{{for product in products}}
  <li class="{{if @odd}}odd{{/if}}">{{@number}}. {{product.name}}</li>
{{else}}
  <li>Nothing here yet.</li>
{{/for}}

{{#tags}}<span>{{.}}</span>{{/tags}}
{{^tags}}<span>No tags</span>{{/tags}}

{{for tags}}<span>{{.}}</span>{{/tags}}

Inside a named loop, read the item by its name. {{.}} there is the context around the loop, not the item.

Partials print another template

A partial may stand only where text goes: not inside a tag, an attribute or a <script>. Layouts and Partials covers storing them.

Translations come from your translation keys

Languages explains the fallback order and where the keys live.

Filters change a value before it is written

A filter follows a pipe: {{price | money "EUR"}}. They chain from left to right, and an argument may be a value too: {{price | times qty | money "EUR"}}. Naming a filter that does not exist is an error when the template compiles, so a typo never reaches a visitor as an empty value.

Numbers, money and dates

Numbers and money follow the page's language, so the same template writes € 1.234,50 on the Dutch page and €1,234.50 on the English one.

Text

Lists and data

The variables a template sees

The fields of the data pin come first, then every custom pin by its name, which wins over a field of the same name. On top of that, web_render adds the document's own values for the page template and its layout.

A web_template or a web_foreach sees your values and web only, so write {{web.nonce}} and {{web.language}} there. Partials see whatever the template around them sees.

Whitespace and limits

• A block tag standing alone on a line leaves no blank line behind, as in Mustache.
• One render may write at most 16 MB. Partials may nest 48 levels deep, so a partial that includes itself fails with a message and does not hang.
• An error names its line and column, for example line 2 col 1: this block is never closed.

Next steps