Template variables

Syntax

A variable is a name in triple braces, with an optional fallback after |:

Hi {{{NAME}}}
Hi {{{NAME|there}}}

Variables work in the subject, the preview text, the HTML, and the plain-text part. Names can use letters, numbers, underscores and dots, and are case-sensitive. Double braces ({{NAME}}) are not variables.

In the visual editor, open the Variables menu to insert one. It lists Contact properties (contact.first_name with the fallback there, contact.last_name, contact.email, and each custom property) and System (OPENSEND_UNSUBSCRIBE_URL). Click an inserted variable to change its Variable and Fallback.

Values at send time

Pass values in template.variables when you send:

{"template":{"id":"welcome","variables":{"NAME":"Ada","total":42}},"to":"ada@example.net"}

For each ordinary template variable, Opensend uses the value you pass, then the variable's fallback. An empty-string value counts as not passed. A variable with no value and no fallback makes the send fail with Missing template variables. Values are strings of up to 2000 characters or numbers. Values are HTML-escaped in the HTML part.

Contact variables (contact.*) and OPENSEND_UNSUBSCRIBE_URL are filled only by broadcasts and automation sends. A plain API send does not look up contact data or generate an unsubscribe link; unsupplied values use their fallback or an empty string.

Define variables through the API

The dashboard infers variables from the text. The templates API can also define them explicitly, with a type and a fallback:

{"variables":[{"key":"name","type":"string","fallback_value":"there"},{"key":"total","type":"number","fallback_value":0}]}

• A template can use at most 50 variables.
• Keys start with a letter or underscore, contain letters, numbers and underscores, are unique, and are up to 50 characters.
• Types are string and number. A passed value must match the type, and a fallback is up to 2000 characters.
• FIRST_NAME, LAST_NAME, EMAIL, RESEND_UNSUBSCRIBE_URL, contact, and this are reserved and cannot be defined.