sample_resolver.rb

class SampleResolver < ActionView::Resolver
  include Singleton

  def find_templates(name, prefix, partial, details)
    scope = details[:database] # ActiveRecord::Relation
    scope.map(&:to_template)
  end
end

class Template < ActiveRecord::Base
  def to_template
    handler = ActionView::Template.handler_for_extension(File.extname(path))
    Template.new(source, path, handler, {
      virtual_path: "template/#{path}",
      updated_at: updated_at,
      format: "html"
    })
  end
end

class ApplicationController
  before_filter :prepend_database_template
  before_filter :register_database_detail

  protected
  def prepend_database_template
    prepend_view_path SampleResolver.instance
  end

  def register_database_detail
    lookup_context.class.register_detail(:database) { nil }
  end
end

class PostsController < ApplicationController
  def show
    @post = Post.find(params[:id])
    render database: Template.order("created_at desc")
  end
end