Params and templates

Destinations work with two tools: params, the named values a destination carries, and templates, the {{…}} variables you write in its URLs, headers, bodies and texts.

ParamsCopy Anchor Link

{
  "params": {
    "message": { "from": "state.message", "required": true },
    "route": { "from": "result.route" },
    "lead_score": { "from": "composites.lead_score" },
    "team": { "value": "inbound" }
  }
}

A param takes its value from a field of the run (from) or is a fixed value (value): a string of up to 500 characters, a number, true, false or null. A destination has up to 30 params, named with letters, digits and _ — up to 48 characters, not starting with a digit.

SourcesCopy Anchor Link

Values keep their JSON type: confidence.route is a number, state an object. A value that doesn't exist — an optional field the caller didn't send, any answer after an engine-error fallback — is null.

Required paramsCopy Anchor Link

Mark a param required when the destination makes no sense without it — a CRM lead without an e-mail. When it resolves to null or an empty string, the destination doesn't fire and the response says why:

{ "key": "create_lead", "type": "http", "status": "skipped", "reason": "missing_param", "param": "email" }

Where params goCopy Anchor Link

Use params for anything that reaches a third party: a webhook or a workflow never receives the state itself, only the params you map — send what the receiver needs and nothing more.

TemplatesCopy Anchor Link

Write {{ and }} around a variable — spaces inside are allowed: {{ params.awb }}.

The editor's Insert… menu next to each field lists the variables you can use there.

Encoding is automaticCopy Anchor Link

You never escape anything by hand: Dcision encodes each value for the place it goes.

As text, strings are inserted as they are, numbers and booleans are printed, objects and arrays become JSON and null becomes an empty string.

JSON bodiesCopy Anchor Link

An http body template is JSON with variables, and a variable's place decides how it is written:

• Outside quotes, it becomes a JSON value — a string with its quotes, a number, true, null, an object.
• Inside quotes, it becomes text inside that string, escaped as needed.

For a decision whose object state has email and company_size fields, with a param email taken from state.email:

{
  "email": {{params.email}},
  "company_size": {{state.company_size}},
  "summary": "Route {{result.route}} at {{confidence.route}} — lead score {{composites.lead_score}}",
  "lead": {{state}}
}

{
  "email": "ana@acme.com",
  "company_size": 500,
  "summary": "Route sales at 0.85 — lead score 0.8414",
  "lead": { "message": "We need pricing for 500 users.", "email": "ana@acme.com", "company_size": 500 }
}

So write {{state.company_size}} — not "{{state.company_size}}" — to send the number 500 instead of the text "500". {{params.email}} needs no quotes either: its value is a string, so it is written with its quotes.

The body must be valid JSON once the variables are filled in: the editor checks it with sample values when you save, and an invalid template is refused with "The body must be JSON once variables are filled in…". A body is up to 10,000 characters. Leave it empty on POST, PUT and PATCH to send the params as a JSON object; GET and DELETE requests have no body.

Template checksCopy Anchor Link

Templates are validated when you save or deploy:

• every variable must exist: {{params.awb}} needs a param named awb, {{state.company_size}} a field of an object state, {{result.route}} a question named route;
• secret names are UPPER_SNAKE_CASE, such as {{secrets.CRM_TOKEN}};
• every {{ needs its }}, with one variable inside;
• secrets can't be used in texts.

A missing secret isn't a schema error — secrets change without a deploy — but a delivery that references one fails until it is set. See Workspace secrets.