How to use `relative_url` inside custom plugin - ruby

Question

I am trying to use relative_url filter inside a plugin.
module Jekyll
module Tags
class MyNewTag < Liquid::Block
include Jekyll::Filters::URLFilters
def initialize(tag_name, block_options, liquid_options)
super
#class = block_options.strip
end
def render(context)
context.stack do
context["class"] = #class
#content = super
path_js = Jekyll::Filters::URLFilters::relative_url("assets/custom.min.css")
path_css = Jekyll::Filters::URLFilters::relative_url("assets/custom.min.js")
end
output = <<~EOS
<link rel="stylesheet" href="#{path_js}">
<script src="#{path_css}"></script>
EOS
end
end
end
end
Liquid::Template.register_tag('MyNewTag', Jekyll::Tags::MyNewTag)
However, Ruby shows NoMethodError: undefined method relative_url' for Jekyll::Filters::URLFilters:Module` - hence I am not able to use it.
How should I include relative_url filter, so that I could use it in my code?

Answer 1

It turns out, that the error was caused by the lack of context variable, which must be passed explicitly by #context = context
It works, if it is formatted this way:
module Jekyll
module Tags
class MyNewTag < Liquid::Block
include Jekyll::Filters::URLFilters
def initialize(tag_name, block_options, liquid_options)
super
#class = block_options.strip
end
def render(context)
context.stack do
context["class"] = #class
#content = super
#context = context
#path_js = relative_url("assets/custom.min.css")
#path_css = relative_url("assets/custom.min.js")
end
output = <<~EOS
<link rel="stylesheet" href="#{#path_js}">
<script src="#{#path_css}"></script>
EOS
end
end
end
end
Liquid::Template.register_tag('MyNewTag', Jekyll::Tags::MyNewTag)