Alan deLevie

ActiveRecord is awesome. Its dynamic finder methods, scopes, and effortless joins make working with a database a snap. But there are always those times when writing raw sql makes more sense. In my case, I was joining across several tables, and then sorting by a value from the joined table. The problem was that my views were written to handle an ActiveRecord object, not a simple hash, which is what a find_by_sql query returns.

Before:

#controller:
@posts = Post.find(:all)
 
#view:
< % @posts.each do |post| %>
   < %= post.title %>
   < %= post.body %>
   < %= post.author %>
   < %= post.date %>
< % end %>

After:

#controller:
@posts = ActiveRecord::Base.connection.execute("SELECT * FROM posts")
# @posts.class #=> Hash
# @posts[0].title will return a method missing error

For the view you have two choices.
1)Rewrite the method calls:

< % @posts.each do |post| %>
    < %= post['title'] %>
    < %= post['body'] %>
   < %= post['author'] %>
    < %= post['date'] %>
&lt; % end %&gt;
#this is tedious

or
2) Hack the hash to make keys act as methods. There are several ways to do this. From a stackoverflow question I asked, someone showed me a module in the Ruby standard library called OpenStruct:

#controller
require 'ostruct'
@posts = OpenStruct.new(ActiveRecord::Base.connection.execute("SELECT * FROM posts"))
 
#view
< % @posts.each do |post| %>
   < %= post.title %>
   < %= post.body %>
   < %= post.author %>
   < %= post.date %>
< % end %>

Other ways to do this (from stackoverflow answerers):

• define the method_missing function for the Hash class
• define the method_missing function for just the hash instance you’re dealing with

You can try these out with a really cool pastebin that actually runs the code:

• OpenStruct
• modify Hash class
• modify specific hash instance

It’s interesting that all of these solutions used about 5mb of memory according to the ideone.com.