When Nunjucks runs

Ripple uses the Nunjucks engine when a field contains logic blocks ({% if %}, {% for %}), filters ({{ name | upper }}), or comments ({# #}).

Nunjucks {% %} templates are desktop-only — not supported in rip CLI.

Plain {{host}} placeholders keep the fast simple substitution path
Existing collections behave the same unless you add Nunjucks syntax
Runs at send time with the same variable resolution order as simple interpolation
Chain runtime overrides still apply on top of global → collection → environment

Variable types in templates

Environment and collection values are stored as strings. Ripple coerces them for Nunjucks when useful:

Store JSON arrays/objects as a single variable value when you need {% for item in items %} loops.

Stored value	Becomes in template
true / false	boolean
42, 3.14	number
["a","b"]	JSON array
{"id":1}	JSON object
anything else	string

Dynamic variables in Nunjucks

Postman-style dynamic variables work inside Nunjucks templates and are resolved before rendering:

{"requestId": "{{ $guid }}", "ts": {{ $timestamp }}}

Filters

Set tags to ["api","v2"] (JSON array string) to get api, v2 from join.

Authorization: Bearer {{ apiToken | trim }}
X-Label: {{ env | upper }}
X-Tags: {{ tags | join(", ") }}

Conditional URL

{% if env == "prod" %}https://api.example.com{% else %}https://staging.example.com{% endif %}/v1/users

Loop-built JSON body

Set ids to [1, 2, 3] as a JSON array variable.

[
{% for id in ids %}
  "{{ id }}"{% if not loop.last %},{% endif %}
{% endfor %}
]

JSON request bodies

{
  "env": "{{ env }}",
  "count": {{ count }},
  "active": {{ enabled }}
}

Simple {{var}} only

Values inside quoted JSON strings are escaped automatically (quotes, newlines, etc.)

Nunjucks logic or filters

The entire body is rendered as one template — you are responsible for valid JSON

Supported Nunjucks features

Not supported: template inheritance ({% extends %}), includes ({% include %}), macros, or file-based templates — only inline strings in request fields.

Feature	Example
Output	{{ variable }}
Filters	{{ name \| upper }}, {{ items \| join(",") }}, {{ x \| default("n/a") }}
Conditionals	{% if %}, {% elif %}, {% else %}, {% endif %}
Loops	{% for item in list %}, loop.first, loop.last, loop.index
Comments	{# not sent #}
Whitespace control	{%- and -%} (trim blocks enabled)

Unresolved variables & errors

Simple {{var}}: unknown names stay as literal {{var}} in output
Nunjucks: unknown names render empty unless you use | default(...)
Ripple warns in the UI when a referenced variable is not defined
Syntax errors are logged; original template text is left unchanged

Where it works

Request URL and query params
Header names and values
Body (JSON, raw, form, GraphQL query/variables, SOAP)
Auth fields resolved through variables
Request chains (each step's URL, headers, body)