The Robb Report

So I found that I keep wanting to integrate various Open Source applications into my Rails apps.  But when I search around to see who’s done that, I don’t find many success stories.

I decided to give the problem a shot, and I think I’ve actually solved it; I’ve created a framework along with Rails and Wordpress plugins that enable transparent single sign-on between them.

The basic idea is that the Rails app stays in control of logins and logouts.  The other applications connect via a web service API to provide the single sign-on function. Here are a couple of screen shots of the Wordpress plugin in the dashboard. 

I got the idea from thinking about the how one of the LDAP plugins functions in Wordpress — it connects to LDAP to perform the authentication, and creates a corresponding Wordpress user on the fly if necessary.

Here’s the Integration_API home page with links to the downloads.

The problem:

All of the examples I could find of how to display images with attachment_fu in Rails look like this:

image_tag(my_photo.public_filename(:small))

I programmed a complete website with this kind of code before I realized that I really need to include height and width attributes in my image tags.  The attachment object has height and width attributes… but in the example above, where I’m displaying the :small thumbnail of an image, I couldn’t find a way, via the API, to retrieve the small image version in order to query its height and width.

How I display images on Green Fabric

If there’s something obvious I’ve missed, please let me know!  At any rate, here’s an example page from Green Fabric, the site where I’m doing this.  Obviously, with this many images, having the height and width is critical.  And I’ve seen a huge difference in the perceived and actual page loading times after making my change.

My solution:

I’m new to Ruby, so I’m sure there’s a much smoother way of doing this, but here’s what I’ve written.  First, my new view template code to display the image in the example above would look like this:

photo_tag(my_photo, "small")

And the tag will include the correct height and width attributes.  Now comes the part where it’s clear that I’m not a Ruby expert.  I’m sure I could have done this by somehow mixing in new code into the attachment_fu library… but I don’t know how to do that.  So I created a couple of helper methods, which is what photo_tag is.  This code is from application_helper.rb:

  def thumbnail_for(full_size_image, thumbnail_name)
    full_size_image.thumbnails.each do |i|
      return i if i['thumbnail'] == thumbnail_name
    end

    return nil
  end

  def photo_tag(photo, thumbnail_name=nil, css_class=nil)
    if thumbnail_name.nil?
      image = photo
    else
      image = thumbnail_for(photo, thumbnail_name)
    end

    if css_class.nil?
      return image_tag(image.public_filename, :size=>image.image_size)
    else
      return image_tag(image.public_filename, :size=>image.image_size, :class=>css_class)
    end
  end

I haven’t written many programming-related posts, but lately I’ve been spending a lot of time working on Green Fabric — a new website built with Ruby on Rails. I’ve been learning Rails as I go, and now I’m starting to feel like I really know what I’m doing. So, with that caveat, here’s my first Rails post:

I really like using proper typographical double quotes.  I use them in several places on Green Fabric, such as this page, which explains OpenID.  Look at the word, register.  Here’s how I do that elegantly.

1. My view template has this code:

Most people don't need to <%= quote_this 'register' %> here

2. My application_helper.rb file has this code:

  def ldquo
    '<span class="serif">&ldquo;</span>'
  end

  def rdquo
    '<span class="serif">&rdquo;</span>'
  end

  def quote_this(html_snippet)
    return ldquo() + html_snippet + rdquo()
  end

(In my css file, I’ve defined a “serif” class to set the font-face.) And that’s it!