example_high_level_app.rb

require 'active_record'
require 'erb'
require 'logger'

ActiveRecord::Base.establish_connection adapter: 'sqlite3', database: ':memory:'
ActiveRecord::Base.logger = Logger.new $stdout
ActiveSupport::LogSubscriber.colorize_logging = false

ActiveRecord::Schema.define do
  self.verbose = false

  create_table :pages do |t|
    t.string  :name
    t.integer :num_locations
    t.text    :template
    # If template, then that implies we need to figure out how to put the contents into it.
    # Otherwise, probably `:body` and delete the contents table.
    # In that case, we can put all of the content into the body,
    # and don't need any abstractions for any of this shit.
  end

  create_table :contents do |t|
    t.string  :body
    t.string  :content_type
    t.integer :page_id
    t.integer :location
  end
end

class Page < ActiveRecord::Base
  has_many :contents
  validates :name, uniqueness: true

  def content_for(n)
    raise IndexError if n < 1
    raise IndexError if n > num_locations
    content = contents.find { |content| content.location == n }
    content || Content.null(n)
  end
end

class Content < ActiveRecord::Base
  def self.null(location=1)
    new location: location, content_type: 'html', body: "Not yet set"
  end

  belongs_to :page

  def type?(type)
    content_type == type.to_s
  end
end

Page.create! do |page|
  page.name          = "Home"
  page.num_locations = 3
  page.contents.build location: 2, content_type: 'html', body: <<-HTML.strip_heredoc
    <div class="video">
      <h1>How Monsanto is doing it</h1>
      <iframe>...</iframe>
    </div>
  HTML

  page.contents.build location: 1, content_type: 'markdown', body: <<-MARKDOWN.strip_heredoc
  This is an h2
  -------------

  And this is a paragraph
  MARKDOWN

  page.template      = <<-HTML.strip_heredoc
    <h1>$NAME</h1>
    
    <p>Check our shit out!</p>
    
    $LOCATION1
    $LOCATION2
    $LOCATION3
    
    <p>Thanks for visiting!</p>
  HTML

end


# /admin/static_pages/home
# route_set.draw do
#   namespace :admin do
#     get   "/static_pages/:name", to: "static_pages#edit",  as: :static_pages
#     put   "/static_pages/:name", to: "static_pages#update"
#     patch "/static_pages/:name", to: "static_pages#update"
#   end
#   get "/:name", to: "static_pages#show", as: :static_pages
# end

class ApplicationController
  attr_accessor :params
  def initialize(params:)
    self.params = params
  end
  def render(whatever)
    # faking out the static pages rendering shit
    app_views_static_pages_show_erb_html = <<-ERB.strip_heredoc
      <nav>Here are some links and shit...</nav>
      <content>
        <%= @template %>
      <content>
    ERB
    
    ERB.new(app_views_static_pages_show_erb_html).result(binding)
  end
end

class StaticPagesController < ApplicationController
  def show
    if params[:name].nil?
      puts "\e[31mExpected params[:name] to be something like 'home', but it's nil!\e[0m"
      p params
      require 'pry'
      binding.pry
    end

    @page     = Page.find_by!(name: params[:name].capitalize)
    @template = MyTemplateRenderer.new(@page).render
    render 'static_page'
  end
end

module Admin
  class StaticPagesController < ApplicationController
    def edit
      # ...
    end
    
    def update
      # ...
    end
  end
end


require 'redcarpet'
class MyTemplateRenderer
  def initialize(page)
    @page = page
  end

  attr_reader :page

  def render
    rendered = @page.template
                    .gsub("$NAME", @page.name)
                    .gsub(/\$LOCATION(\d+)/) { |n| content_for $1.to_i }
    
    if rendered.include?('<%')
      raise "Wtf?! there's erb in this template: #{rendered.inspect}"
    end

    rendered
  end
  
  def content_for(location)
    content = page.content_for(location)
    body    = content.body
    if content.type? :markdown
      renderer = Redcarpet::Render::HTML.new
      markdown = Redcarpet::Markdown.new(renderer)
      body = markdown.render(body)
    end
    body
  end
end

puts StaticPagesController
       .new(params: {name: "home"})
       .show

# >> D, [2015-07-29T12:14:36.114904 #20567] DEBUG -- :    (0.4ms)  CREATE TABLE "pages" ("id" INTEGER PRIMARY KEY AUTOINCREMENT NOT NULL, "name" varchar, "num_locations" integer, "template" text) 
# >> D, [2015-07-29T12:14:36.115352 #20567] DEBUG -- :    (0.1ms)  CREATE TABLE "contents" ("id" INTEGER PRIMARY KEY AUTOINCREMENT NOT NULL, "body" varchar, "content_type" varchar, "page_id" integer, "location" integer) 
# >> D, [2015-07-29T12:14:36.155901 #20567] DEBUG -- :    (0.1ms)  begin transaction
# >> D, [2015-07-29T12:14:36.162014 #20567] DEBUG -- :   Page Exists (0.1ms)  SELECT  1 AS one FROM "pages" WHERE "pages"."name" = 'Home' LIMIT 1
# >> D, [2015-07-29T12:14:36.162668 #20567] DEBUG -- :   SQL (0.1ms)  INSERT INTO "pages" ("name", "num_locations", "template") VALUES (?, ?, ?)  [["name", "Home"], ["num_locations", 3], ["template", "<h1>$NAME</h1>\n\n<p>Check our shit out!</p>\n\n$LOCATION1\n$LOCATION2\n$LOCATION3\n\n<p>Thanks for visiting!</p>\n"]]
# >> D, [2015-07-29T12:14:36.163386 #20567] DEBUG -- :   SQL (0.1ms)  INSERT INTO "contents" ("location", "content_type", "body", "page_id") VALUES (?, ?, ?, ?)  [["location", 2], ["content_type", "html"], ["body", "<div class=\"video\">\n  <h1>How Monsanto is doing it</h1>\n  <iframe>...</iframe>\n</div>\n"], ["page_id", 1]]
# >> D, [2015-07-29T12:14:36.164008 #20567] DEBUG -- :   SQL (0.0ms)  INSERT INTO "contents" ("location", "content_type", "body", "page_id") VALUES (?, ?, ?, ?)  [["location", 1], ["content_type", "markdown"], ["body", "This is an h2\n-------------\n\nAnd this is a paragraph\n"], ["page_id", 1]]
# >> D, [2015-07-29T12:14:36.164299 #20567] DEBUG -- :    (0.0ms)  commit transaction
# >> D, [2015-07-29T12:14:36.196117 #20567] DEBUG -- :   Page Load (0.2ms)  SELECT  "pages".* FROM "pages" WHERE "pages"."name" = ? LIMIT 1  [["name", "Home"]]
# >> D, [2015-07-29T12:14:36.197559 #20567] DEBUG -- :   Content Load (0.1ms)  SELECT "contents".* FROM "contents" WHERE "contents"."page_id" = ?  [["page_id", 1]]
# >> <nav>Here are some links and shit...</nav>
# >> <content>
# >>   <h1>Home</h1>
# >> 
# >> <p>Check our shit out!</p>
# >> 
# >> <h2>This is an h2</h2>
# >> 
# >> <p>And this is a paragraph</p>
# >> 
# >> <div class="video">
# >>   <h1>How Monsanto is doing it</h1>
# >>   <iframe>...</iframe>
# >> </div>
# >> 
# >> Not yet set
# >> 
# >> <p>Thanks for visiting!</p>
# >> 
# >> <content>

isolated_rendering_example.rb

require 'redcarpet'
      
class MyTemplateRenderer
  def initialize(page)
    @page = page
  end

  attr_reader :page

  def render
    rendered = @page.template
                    .gsub("$NAME", @page.name)
                    .gsub(/\$LOCATION(\d+)/) { |n| content_for $1.to_i }
    
    if rendered.include?('<%')
      raise "Wtf?! there's erb in this template: #{rendered.inspect}"
    end

    rendered
  end
  
  def content_for(location)
    content = page.content_for(location)
    body    = content.body
    if content.type == :markdown
      renderer = Redcarpet::Render::HTML.new
      markdown = Redcarpet::Markdown.new(renderer)
      body = markdown.render(body)
    end
    body
  end
end

class Page
  def initialize(name, template, contents)
    @name, @template, @contents = name, template, contents
  end

  attr_accessor :name, :template

  def content_for(location)
    @contents[location-1]
  end
end

Content = Struct.new :type, :body

contents = [
  Content.new(:html, <<-HTML),
 <div class="banner">
   Connecting Businesses, Communities and the Tech Talent Pipeline
 </div>
 HTML
 
 Content.new(:markdown, <<-MARKDOWN.gsub(/^ */, '')),
 This is an h2
 -------------

 And this is a paragraph
 MARKDOWN
 
 Content.new(:html, <<-HTML),
 <div class="video">
   <h1>How Monsanto is doing it</h1>
   <iframe>...</iframe>
 </div>
 HTML
]

page = Page.new("Home", <<-HTML, contents)
<h1>$NAME</h1>

<p>Check our shit out!</p>

$LOCATION1
$LOCATION2
$LOCATION3

<p>Thanks for visiting!</p>
HTML

puts MyTemplateRenderer.new(page).render

# >> <h1>Home</h1>
# >> 
# >> <p>Check our shit out!</p>
# >> 
# >>  <div class="banner">
# >>    Connecting Businesses, Communities and the Tech Talent Pipeline
# >>  </div>
# >> 
# >> <h2>This is an h2</h2>
# >> 
# >> <p>And this is a paragraph</p>
# >> 
# >>  <div class="video">
# >>    <h1>How Monsanto is doing it</h1>
# >>    <iframe>...</iframe>
# >>  </div>
# >> 
# >> 
# >> <p>Thanks for visiting!</p>