SearchLogic problems due to caching of method calls - ruby-on-rails

Question

I am trying to use the searchlogic gem to perform searches over a couple tables Post has_many assets. I need it to perform left outer joins rather than inner joins in the event of a non-existant asset.
From what I have below the query is generated with the required outer joins, and passes the first three tests, but fails on the last. However, if I only run the last test it then passes.
The reason for the failing is that the #search_logic_filter var is only being set on the first test and is used for all of the remaining tests.
The reason for the setting of the #search_logic_filter in this way is that it is the only call to method_missing that carries the param passed to the dynamic searchlogic method call of Post.title_or_body_or...like("fun")
Is there a better way to set the filter param?
test "find posts and assets by filter for user" do
customer = users(:customer)
create_post_for_user(customer, {:body => "Rails is fun", :tags => "rails ruby"})
create_post_for_user(customer, {:body => "Fun is what Emacs is all about", :title => "emacs"})
# File with post
asset_post = create_post_for_user(customer, {:body => "Ruby is pretty fun too",
:tags => "ruby"})
asset_post.assets << Asset.new(:upload_file_name => "ruby_tips",
:upload_file_size => 100,
:upload_content_type => "text")
asset_post.save
# search post
assert_equal 3, Post.find_for_user(customer.id, "fun").size
assert_equal 2, Post.find_for_user(customer.id, "ruby").size
assert_equal 1, Post.find_for_user(customer.id, "emacs").size
# search asset
puts "about to run last test"
assert_equal 1, Post.find_for_user(customer.id, "ruby_tips").size
end
class Post < ActiveRecord::Base
def self.find_for_user(user_id, filter, page=1)
Post.
user_id_equals(user_id).
title_or_body_or_tags_or_assets_upload_file_name_like(filter).all
end
class << self
def method_missing(name, *args, &block)
if name.to_s =~ /\w+_or_\w+_like$/
# ** only gets here once **
#search_logic_filter = args.first
super
elsif name == :assets_upload_file_name_like
# args is [] here which is the reason for the above setting of #search_logic_filter
named_scope :assets_upload_file_name_like, lambda {
{:joins => "left outer join assets on posts.id = assets.post_id",
:conditions => "assets.upload_file_name like '%#{#search_logic_filter}%'"}
}
assets_upload_file_name_like
else
super
end
end
end
end
** update
This is the query that is run for the final test. Notice that the upload_file_name param is 'fun', not 'ruby_tips'. The 'fun' param exists for all the tests for the upload_file_name col, but it only matters for the last test.
SELECT `posts`.*
FROM `posts`
left outer join assets
on posts.id = assets.post_id
WHERE (
((posts.title LIKE '%ruby_tips%') OR (posts.body LIKE '%ruby_tips%') OR (posts.tags LIKE '%ruby_tips%') OR (assets.upload_file_name like '%fun%'))
AND (posts.user_id = 20549131)
)

Answer 1

You should not declare the named_scope assets_upload_file_name_like that way. When it's called the first time, the assets_upload_file_name_like named scope is defined with the the value for :conditions generated according the value of #search_logic_filter at that time. You should set the parameter on the lambda instead.
There's also no need to use method_missing. Just declare the named_scope within the Post class. As a bonus, the query should be filtered to guard against SQL injection attacks.
class Post < ActiveRecord::Base
named_scope :assets_upload_file_name_like, lambda { |file_name| {
:joins => "left outer join assets on posts.id = assets.post_id",
# Prevent SQL injection.
:conditions => ["assets.upload_file_name like ?", "%#{file_name}%"]
}}
end