Rails Tidbits

I have been doing what seems like 24x7 rails development for many months (years?) now and have gathered up some useful tidbits that I don't want to forget.

The most recent I've just written tonight.

I needed a way to send myself an email containing the cause of the error when a user tried to change their profile, reset password, etc, and the update failed due to a validations error.

So I wrote a little helper method for my application_helper.rb:

  def human_readable_errors(errors, col_names)
    arr = Array.new
    for name in col_names
      if errors[name] && errors[name].is_a?(Array)
        arr << name + ": {" + errors[name].compact.join(', ') + "}"
      elsif errors[name]
        arr << name + ": {" + errors[name].to_s + "}"
      end
    end
    return arr.to_sentence
  end

Now in my mailer model I can send emails with this lovely line:

  def profile_update_failure(user, original)
    @recipients = "no-spam@peterboling.com"
    @from       = "Admin "
    @subject    = "[ERROR] Profile Update Failure (#{user.login})"
    @sent_on    = Time.now
    @content_type = "text/plain"
    @body  = { 
              :name => user.name,
              :login_name => user.login,
              :message => "Profile was NOT updated.\n\r" + get_object_diff(user, original),
              :date => Time.now.to_date.to_s,
              :time => Time.now.strftime("%I:%M %p"),
              :errors => "Profile update failed because:\r\n\r\n" + human_readable_errors(user.errors, User.column_names)
             }
  end

And I will get an email with some lines like this:

Resetting password failed because:

login: {is too short (minimum is 1 characters), can't be blank, can't be changed ... ever} and last_name: {can't be blank}"

You may have noticed the get_object_diff method call. That's the easiest way to see if the user has changed anything, and what EXACTLY they changed. This way I have a record of all the changes in email (which I prefer to storing this sort of thing in a database. I use the email history as the record of what changed when.)

So I put the get_object_diff method in my mailer_helper.rb because I only use it when mailing... (Oh and the object class must be acts_as_comparable)

  #Object class must be acts_as_comparable
 def get_object_diff(first, second)
    i = 0
   j = 0
   diff = first.differences(second).to_a
   d = String.new
    up = String.new
   for p in diff
     i += 1
     if p.is_a?(Array)
       for s in p
         j += 1
         if !s.is_a?(Array) && s != :updated_at
           d += s.to_s.humanize + ": "
         elsif !s.is_a?(Array) && s == :updated_at
            up += s.to_s.humanize + ": "
          elsif p[0] != :updated_at
            d += s.reverse.to_sentence(:connector => 'changed to', :skip_last_comma => true)
            d += "\n\r"
          elsif p[0] == :updated_at
            up += s[0].to_s
            up += "\n\r"
         else
           d += "and " + s[0].to_s
           d += "\n\r"
         end
       end
       j = 0
     end
   end
   return d + (up || "")
  end

The output of this method generates somthing like this example:

The following things were updated in your profile:
        
City: Pickadilly changed to South Bend

Address1: 597 N Fizzling Sticks Ave #42 changed to 653 E 6th Ave

Postal code: 47304 changed to 22222

Phone: 555-555-1234 changed to 

Email: no-spam@peterboling.com changed to please-spam@yahoo.com

State: MO changed to NY

Updated at: Tue Aug 28 14:51:36 UTC 2007

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