Interpolate Sting Using Hash or Rails Model

custom_utils.rb

module CustomUtils
  # This should look for hash keys, or ActiveModel::Base attributes within the string
  # while also safeguarding from typing errors.
  # Interpolation symbols not provided in the hash should be left unchanged.
  # This does NOT support "deep interpolation" eg. "my %{%{nested_key}} string"
  #@param String with %{key} interpolation fields
  #@param Hash with symbolic keys OR Object with 'attributes' method eg. ActiveModel
  #@returns String original with any keys replaced if they are in the hash, others ignored
  def self.interpolate str, obj
    #For the hash, we need to re-key the hash to be sure, and add default to skip missing interpolations
    safe_hash = (defined?(obj.attributes) ? obj.attributes : obj.to_h).symbolize_keys
    safe_hash.default_proc = proc{|h, k| "%{#{k}}" }
    #On the string side, safeguard any place ther is a symbol inside an interpolated field
    str.gsub('%{:', '%{') % safe_hash
  end
end

Usage:
CustomUtils.interpolate "status = %{status}", Resource.first
CustomUtils.interpolate "hello %{world_type} world", {world_type: :wonderful}