Soapbox Confessional

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Viviti helps you build websites.

InQuickER lets you to go to the emergency department without waiting in the waiting room.

About

I'm Tyler: Entrepreneur, geek, free thinker, bringer of chaos (but not carnage).

I live on the beach on Vancouver Island, where life is wonderful and continues to improve.

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Tech Notes

Fun with single table inheritance

Posted September 16, 2008

Viviti uses a lot of single table inheritance. Because of the particular details of our project, we've implemented a few quick conventions and extensions to Rails' STI goodness. One of my favorites, extracted from a module we use in several different places:

# STI-friendly new() method automatically instantiates the proper subclass
class MySupertype::Base < ActiveRecord::Base
  def self.new(atts = nil)
    atts ||= {}
    if atts[:type] and klass = "MySupertype::#{atts[:type].classify}".constantize and klass != self and klass.ancestors.include?(self)
      return klass.new( atts )
    end
    
    return super
  end
end
This code allows you to call MySupertype::Base.new with :type => 'MySubclass' and it will Just Work™.

Tagged as rails

Sane event handling for change events on select tags

Posted September 16, 2008

If you've ever tried to attach an onchange event handler to a <select> tag, you've definitely noticed that different browsers handle them in annoyingly different ways. This afternoon I whipped up a snippet of jquery code that makes them behave like they ought:

// onchange() on select boxes is handled in a variety of retarded ways by different browsers.
// this patch (hopefully) makes them all work like you would expect them to.
$.event.special.change = {
  setup: function() {
    // only monkeypatch if we're dealing with a select element and we're not dealing with Safari.
    if(this.tagName.toLowerCase() != 'select' || $.browser.safari) return false;
    $(this).data('oldVal', $(this).val());
    $(this).bind("click keydown", $.event.special.change.handler);
    return true;
  },

  teardown: function() {
    $(this).unbind("click keydown", $.event.special.change.handler);
  },

  handler: function(event) {
    var args = arguments;
    setTimeout($.bind_function(function() {
      if($(this).val() != $(this).data('oldVal')) {
        $(this).data('oldVal', $(this).val());
        args[0].type = 'change';
        return $.event.handle.apply(this, args);
      } else {
        return true;
      }
    }, this), 1);
    return true;
  }
};

1 comment
Tagged as jquery and javascript