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Jamie Wilkinson http://tramchase.com

jQuery and Rails' respond_to

// Just throw this at the bottom of your application.js and you’re good to go: all jQuery ajax requests will trigger the wants.js block of your respond_to declaration, exactly like you’d expect. Enjoy.
// via: http://ozmm.org/posts/jquery_and_respond_to.html

jQuery.ajaxSetup({beforeSend’: function(xhr) {xhr.setRequestHeader(“Accept”,text/javascript”)} })

simple Ruby RSS reader

// fetch & parse RSS into an object

require 'rss/2.0'
require 'open-uri'

class RssReader

  def parseFeed (url, length)
    feed_url = url
    output = "";
    open(feed_url) do |http|
      response = http.read
      result = RSS::Parser.parse(response, false)
      output = "<span class=\"feedTitle\">#{result.channel.title}</span><br /><ul>" 
      result.items.each_with_index do |item, i|
        output += "<li><a href=\"#{item.link}\">#{item.title}</a></li>" if ++i < length  
      end 
      output += "</ul>" 
    end
    return output
  end

end

acts_as_state_machine model

// ActiveRecord plugin for managing state changes
// elitists.textdriven.com/svn/plugins/acts_as_state_machine/

class Something < ActiveRecord::Base

  # Validations
  validate :validate_state_change

  # State Machine States
  acts_as_state_machine :initial => :new
  state :new
  state :enabled,   :after => :after_enabled
  state :disabled,  :after => :after_disabled

  # State Machine Events
  event :enabled do
    transitions :from => :new,      :to => :enabled
    transitions :from => :disabled, :to => :enabled
  end
  
  event :disabled do
    transitions :from => :new,      :to => :disabled
    transitions :from => :enabled,  :to => :disabled
  end

  # Instance Methods
  def validate_state_change
    return if new_record?
    old = self.class.find(id)
    old_state = old.state
    new_state = self.state
    self.state = old_state
    if old_state != new_state
      begin
        if self.method("#{new_state}!").call != true
          errors.add(:state, "cannot transition from #{old_state} to #{new_state}")
        end
      rescue NameError
      end
      self.state = new_state
    end
  end
end

Javascript Bookmarklets

// various bookmarklets for cloning

javascript:var d=document,f='http://www.facebook.com/share',l=d.location,e=encodeURIComponent,p='.php?src=bm&v=4&i=1190041327&u='+e(l.href)+'&t='+e(d.title);1;try{if(!/^(.*\.)?facebook\.[^.]*$/.test(l.host))throw(0);share_internal_bookmarklet(p)}catch(z){a=function(){if(!window.open(f+'r'+p,'sharer','toolbar=0,status=0,resizable=0,width=626,height=436'))l.href=f+p};if(/Firefox/.test(navigator.userAgent))setTimeout(a,0);else{a()}}void(0)


javascript:location.href='http://rickrolldb.com/entries/new?url='+encodeURIComponent(location.href)+'&title='+encodeURIComponent(document.title);

MailMan listserve signup template

Simple template for adding a MailMan mailing list subscribe form to a page. Found on a mailing list somewhere a long time ago and cleaned up dramatically.

Note: I almost always just include the email and digest options, but I've included the whole spiel for completeness.


<h2>Join the XYZ list</h2>

<form method="post" action="SERVER/mailman/subscribe/LISTNAME">

  <p>
    Your E-mail address: <input type="text" name="email" size="30" value=""><br />
    Your Name (optional): <input type="text" name="fullname" size="30" value=""><br />
  </p>

  <p>You may enter a privacy password below. This provides only mild security, but should<br />
  prevent others from messing with your subscription. <b>Do not use a valuable password</b> as it<br />
  will occasionally be emailed back to you in cleartext.</p>

  <p>If you choose not to enter a password, one will be automatically generated for you, and it will<br />
  be sent to you once you've confirmed your subscription. You can always request a mail-back<br />
  of your password when you edit your personal options.</p>

  <p>
    Password choice: <input type="password" name="pw" size="15"><br />
    Confirm Password: <input type="password" name="pw-conf" size="15">
  </p>

  <p>
    Would you like to receive list mail batched in a daily digest? (You may choose NoMail after you join.)<br />
    <input type="radio" name="digest" value="0" checked> No 
    <input type="radio" name="digest" value="1"> Yes <br />
  </p>
  
  <p><input type="submit" name="email-button" value="Subscribe"></p>

</form>


Convert MySQL tables to InnoDB

// Slower than MyISAM, but row locking is clutch if you're doing a lot of writes amirite?

for t in $(mysql --batch --column-names=false -e "show tables" mydbname |grep -v "exclude_this");
do
mysql -e "alter table $t type=InnoDB" mydbname;
done


From:
http://ludo.qix.it/archive/2005/04/convert-a-bunch-of-tables-to-innodb.html

Delete duplicate rows from a table

// Whoops, didja forgot to add a unique index to that column? No problem

CREATE TABLE new_table AS
SELECT * FROM old_table WHERE 1 GROUP BY [COLUMN TO remove duplicates BY];
DROP TABLE old_table;
RENAME TABLE new_table TO old_table;

Capistrano task to load production data

# load production data, still needs some polish
# based on code from http://push.cx/2007/capistrano-task-to-load-production-data
# cap 2.0 compatible
# exec is being weird, had to end w/ a syscall :\ any ideas?

desc "Load production data into development database"
task :load_production_data, :roles => :db, :only => { :primary => true } do
  require 'yaml'
  ['config/database.yml'].each do |file|

    database = YAML::load_file(file)

    filename = "dump.#{Time.now.strftime '%Y-%m-%d_%H:%M:%S'}.sql.gz"
    # on_rollback { delete "/tmp/#{filename}" }

    # run "mysqldump -u #{database['production']['username']} --password=#{database['production']['password']} #{database['production']['database']} > /tmp/#{filename}" do |channel, stream, data|
    run "mysqldump -h #{database['production']['host']} -u #{database['production']['username']} --password=#{database['production']['password']} #{database['production']['database']} | gzip > /tmp/#{filename}" do |channel, stream, data|
      puts data
    end
    get "/tmp/#{filename}", filename
    # exec "/tmp/#{filename}"
    password = database['development']['password'].nil? ? '' : "--password=#{database['development']['password']}"  # FIXME pass shows up in process list, do not use in shared hosting!!! Use a .my.cnf instead
    # FIXME exec and run w/ localhost as host not working :\
    # exec "mysql -u #{database['development']['username']} #{password} #{database['development']['database']} < #{filename}; rm -f #{filename}"
    `gunzip -c #{filename} | mysql -u #{database['development']['username']} #{password} #{database['development']['database']} && rm -f gunzip #{filename}`
  end
  
end

Get remote file size, following redirects (PHP)

function get_remote_file_size($url, $readable = true){
   $parsed = parse_url($url);
   $host = $parsed["host"];
   $fp = @fsockopen($host, 80, $errno, $errstr, 20);
   if(!$fp) return false;
   else {
       @fputs($fp, "HEAD $url HTTP/1.1\r\n");
       @fputs($fp, "HOST: $host\r\n");
       @fputs($fp, "Connection: close\r\n\r\n");
       $headers = "";
       while(!@feof($fp))$headers .= @fgets ($fp, 128);
   }
   @fclose ($fp);
   $return = false;
   $arr_headers = explode("\n", $headers);
   foreach($arr_headers as $header) {
			// follow redirect
			$s = 'Location: ';
			if(substr(strtolower ($header), 0, strlen($s)) == strtolower($s)) {
				$url = trim(substr($header, strlen($s)));
				return get_remote_file_size($url, $readable);
			}
			
			// parse for content length
       $s = "Content-Length: ";
       if(substr(strtolower ($header), 0, strlen($s)) == strtolower($s)) {
           $return = trim(substr($header, strlen($s)));
           break;
       }
   }
   if($return && $readable) {
			$size = round($return / 1024, 2);
			$sz = "KB"; // Size In KB
			if ($size > 1024) {
				$size = round($size / 1024, 2);
				$sz = "MB"; // Size in MB
			}
			$return = "$size $sz";
   }
   return $return;
}

Never render the full layout in a Rails view when called via AJAX

Essential for degradable javascript, when one never knows if a view or partial is being called via XmlHttpRequest or not. Throw the below code in your ApplicationController (application.rb)

More info in this blog post

def render(*args)
  	args.first[:layout] = false if request.xhr? and args.first[:layout].nil?
	super
end