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How to generate a PDF from a template in Ruby on Rails

Call the Inkspan /v1/generate/template endpoint from Ruby on Rails to generate a PDF from a template — no headless browser, font stack, or rendering infrastructure in your deploy. Keep your API key in the environment and POST.

send_data is the idiomatic way to return the PDF to a browser. Use Rails credentials or an environment variable for the key.

Ruby on Rails example

# app/controllers/pdf_controller.rb
require 'net/http'

def create
  uri = URI('https://api.inkspan.dev/v1/generate/template')
  res = Net::HTTP.post(uri, {"template": "<h1>{{ name }}</h1>", "data": {"name": "Ada"}}.to_json, {
    'X-API-Key' => ENV.fetch('INKSPAN_KEY'),
    'Content-Type' => 'application/json',
  })

  raise res.body unless res.is_a?(Net::HTTPSuccess)
  send_data res.body, type: 'application/pdf', disposition: 'attachment'
end

Request parameters

Name	Type	Required	Description
`template`	string	yes	A Jinja2 template. Supports `{{ variables }}`, `{% for %}` loops, `{% if %}` conditionals, and filters.
`data`	object	yes	JSON object whose top-level keys become template variables.
`filename`	string	no	Filename in the response's Content-Disposition.

Response

Returns a PDF as a binary stream with Content-Type: application/pdf and Content-Disposition: attachment; filename=document.pdf. Write the response body straight to disk — do not parse it as JSON.

Production notes

Wrap the call in a background job with Active Job if the document is large; a synchronous render blocks a Puma thread.

Template syntax is Jinja2, not Handlebars or Mustache. Loops are {% for i in items %}…{% endfor %}, not {{#each}}.
Only top-level keys in data become variables. Passing {"data": {"invoice": {...}}} means you reference {{ invoice.number }}, not {{ number }}.
Undefined variables render as empty rather than raising. Validate your data server-side if a missing field should be an error.

Errors

Status	Meaning	Fix
`401`	Invalid or missing API key	Send your key in the `X-API-Key` header.
`402`	Monthly quota exceeded	The response reports used/quota. Upgrade at inkspan.dev/#pricing.
`422`	Missing or invalid parameter	Check required fields in the table above — the body names the offending field.

Failed requests do not count against your quota; only successful ones are metered.

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Same operation in cURL · Python · Node.js · Other frameworks: Next.js · Django · Laravel · PHP · All guides