Render an ERB template with values from a hash

Question

I must be overlooking something very simple here but I can't seem to figure out how to render a simple ERB template with values from a hash-map.

I am relatively new to ruby, coming from python. I have an ERB template (not HTML), which I need rendered with context that's to be taken from a hash-map, which I receive from an external source.

However, the documentation of ERB, states that the ERB.result method takes a binding. I learnt that they are something that hold the variable contexts in ruby (something like locals() and globals() in python, I presume?). But, I don't know how I can build a binding object out of my hash-map.

A little (a lot, actually) googling gave me this: http://refactormycode.com/codes/281-given-a-hash-of-variables-render-an-erb-template, which uses some ruby metaprogramming magic that escapes me.

So, isn't there a simple solution to this problem? Or is there a better templating engine (not tied to HTML) better suited for this? (I only chose ERB because its in the stdlib).

Answer 1

require 'erb' require 'ostruct'  def render(template, vars)   ERB.new(template).result(OpenStruct.new(vars).instance_eval { binding }) end 

e.g

render("Hey, <%= first_name %> <%= last_name %>", first_name: "James", last_name: "Moriarty") # => "Hey, James Moriarty"  

Update:

A simple example without ERB:

def render(template, vars)   eval template, OpenStruct.new(vars).instance_eval { binding } end 

e.g.

render '"Hey, #{first_name} #{last_name}"', first_name: "James", last_name: "Moriarty" # => "Hey, James Moriarty 

Update 2: checkout @adam-spiers comment below.

Answer 2

I don't know if this qualifies as "more elegant" or not:

require 'erb' require 'ostruct'  class ErbalT < OpenStruct   def render(template)     ERB.new(template).result(binding)   end end  et = ErbalT.new({ :first => 'Mislav', 'last' => 'Marohnic' }) puts et.render('Name: <%= first %> <%= last %>') 

Or from a class method:

class ErbalT < OpenStruct   def self.render_from_hash(t, h)     ErbalT.new(h).render(t)   end    def render(template)     ERB.new(template).result(binding)   end end  template = 'Name: <%= first %> <%= last %>' vars = { :first => 'Mislav', 'last' => 'Marohnic' } puts ErbalT::render_from_hash(template, vars) 

(ErbalT has Erb, T for template, and sounds like "herbal tea". Naming things is hard.)