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I've written an internal standalone gem that generates PDF with Gotenberg rendering an ERB HTML template dynamically. This permits to actually generate a PDF outside a controller context for any possible reason, like reports etc.
This is achieved with inline code. For example:
ERB.new(template).result(binding)
When using render inside a template, i get undefined method 'render', cause of course it's not in the current binding. My goal is to use the existing partial rendering process.
Consider having these three templates:
_header.html.erb
<h1>My Header</h1>
_footer.html.erb
<p>My Footer</p>
layout.html.erb
<body>
<%= render 'header' %>
<%= yield %>
<%= render 'footer' %>
</body>
Is there any way to achieve this?
862
asked Oct 28 '25 19:10
Not completely sure about how you intend to use it but, this works for similar needs.
Assuming a folder structure like this:
.
├── app.rb
└── views
├── _footer.erb
├── _header.erb
├── _index.erb
└── layout.erb
...You can build a small templating engine in ERB like this, inside app.rb
require 'erb'
require 'date'
class SimpleTemplate
attr_reader :views
def initialize(views: 'views')
@views = views
end
def render(template_name, locals = {})
path = File.join(views, "#{template_name}.erb")
html = erb(path, locals)
layout = File.join(views,"layout.erb")
File.exist?(layout) ? erb(layout, locals.merge(content: html)) : html
end
private
def erb(path, locals)
return "" unless File.exist?(path)
b = binding
locals.transform_keys(&:to_sym).each { |k, v| b.local_variable_set(k, v) }
ERB.new(File.read(path), trim_mode: '-').result(b)
end
def render_partial(name)
path = "#{views}/#{name}"
File.exist?(path) ? erb(path, {}) : ""
end
end
Test it with puts SimpleTemplate.new.render('_index')
The content of views/_index.erb
<main>
<section>
<p>Contenuto principale della pagina.</p>
<p>Oggi è <%= Date.today %>.</p>
</section>
</main>
... views/layout.erb
<!DOCTYPE html>
<html lang="it">
<head>
<meta charset="UTF-8">
<title>Il mio sito</title>
</head>
<body>
<%= render_partial('_header.erb') %>
<%= content %>
<%= render_partial('_footer.erb') %>
</body>
</html>
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