require_dependency "renalware/system"
require "liquid" # See https://github.com/Shopify/liquid
module Renalware
module System
class RenderLiquidTemplate
def self.call(**args)
new.call(**args)
end
# Takes the #body of a database-stored Template model, parses it with the Liquid gem to insert
# variables, and return the resulting html.
# Raises an exception id the template is not found or a variable the template requires was
# not supplied.
#
# The body stored in the template#body could be any an html fragment or the whole page, but if
# the latter if should be the inner html of the <body> tag and not contain a <body> tag itself
# Any <style> tags (ie css) will have to be also inside the body, which works fine; there is
# currently no support for rendering items the page <head> for instance. Any images must be
# embedded as binary data.
#
# This approach allows us to render hospital-defined content in a small number of places -
# for Barts can print an ESI as a PDF form (eg at patients/xxx/pd/peritonitis_eposides/1.pdf)
# to let them capture extra detail manually. Using this class lets us search for and load a
# hospital-defined template to use in an instance as this. It reduces support overhead as
# the templates table can be updated manually (by someone qualified); for example a designer
# could make changes to the content and his work (html content with css in a style section as
# described above) updated in the database.
#
# The one caveat is the insertion of variables. These have to be passed in the `variables`
# argument which is a hash of Liquid::Drop instances (see for example PatientDrop) - this is
# just a safe read-only decorator around the data you want to use in a template (for
# example "<h1>{{ patient.name }}</h1>")
# See https://github.com/Shopify/liquid/wiki/Introduction-to-Drops
#
# Note this template approach is for adhoc hospital-defined content only as a means to add
# customisation in certain edge cases, and should not be leaned on in preference to the
# conventional rendering of actions/views explicitly, otherwise mayhem will result ;0)
#
# Example usage:
#
# RenderLiquidTemplate.call("name_of_my_template",
# patient: PatientDrop.new(patient),
# prescriptions: PrescriptionsDrop.new(patient)
#
def call(template_name:, variables: nil)
liquify_template(template_name, variables)
end
private
def liquify_template(template_name, variables = {})
Liquid::Template.error_mode = :strict
template = Template.find_by!(name: template_name)
liquified_template = Liquid::Template.parse(template.body)
liquified_template.render!(variables, { strict_variables: true })
end
end
end
end