Question

In Ruby on Rails 3 (currently using Beta 4), I see that when using the form_tag or form_for helpers there is a hidden field named _snowman with the value of ☃ (Unicode \x9731) showing up.

So, what is this for?

Answer 1

This is here to support Internet Explorer 5 and encourage it to use UTF-8 for its forms.

The commit message seen here details it as follows:

Fix several known web encoding issues:

• Specify accept-charset on all forms. All recent browsers, as well as
  IE5+, will use the encoding specified
  for form parameters
• Unfortunately, IE5+ will not look at accept-charset unless at least one
  character in the form’s values is not
  in the page’s charset. Since the
  user can override the default
  charset (which Rails sets to UTF-8),
  we provide a hidden input containing
  a unicode character, forcing IE to
  look at the accept-charset.
• Now that the vast majority of web input is UTF-8, we set the inbound
  parameters to UTF-8. This will
  eliminate many cases of incompatible
  encodings between ASCII-8BIT and
  UTF-8.
• You can safely ignore params[:_snowman]

In short, you can safely ignore this parameter.

Still, I am not sure why we’re supporting old technologies like Internet Explorer 5. It seems like a very non-Ruby on Rails decision if you ask me.