altFormat not working in jQuery datepicker input field

Question

I have date field (id begin-date)

$( "#begin-date" ).datepicker({ 
  minDate: -20,
  maxDate: "+1M +10D",
  dateFormat: "yy-mm-dd",
  altFormat: "yymmdd"
});

On post, it prints the format as yy-mm-dd (2010-12-08), when it should print as yymmdd (20101208)

Any ideas of why it is not posting it properly with altFormat set?

input field rendered:

<input type="text" name="begin_date" id="begin-date" class="validate[required]" value="" />

Answer 1

The altFormat option doesn't control the formatting of the input with the date picker, but the format of an alternate (usually hidden) field specified by the altField option, like this:

$("#begin-date").datepicker({ 
  minDate: -20,
  maxDate: "+1M +10D",
  dateFormat: "yy-mm-dd",
  altFormat: "yymmdd",
  altField: "#alt-date"
});

You can test it out here; what you probably want is to just put the name on that alt field and that's what'll get posted...without a name the field with the date picker won't get serialized/submitted, for example:

<input type="text" id="begin-date" class="validate[required]" />
<input type="text" id="alt-date" name="begin_date" />