submit multiple forms as if it was a single form

multiform.coffee

$(->
  $doc = $(document)
  $doc.on('submit', 'form[data-parent]', (e) ->
    $target = $(e.currentTarget)
    # we have 2 options here:
    # 1) find all these sub forms on page load
    # 2) find them all on each form submit
    # I like option 2 better because it works with dynamically added/removed forms, at the slight cost of running more selectors
    parentSelector =  $target.data('parent')
    $parentForm = $(parentSelector) #the attribute must be a selector. Maybe add a sanity check for it being a selector so jquery doesnt barf if its not?
    if $parentForm.length == 1
      e.preventDefault() #if there is no parent form, then this form will submit as usual
      $forms = $doc.find("form[data-parent='#{parentSelector}']")
      valid = true
      _.each($forms, (form) ->
        if not $(form).valid()
          valid = false
      )
      if valid and $parentForm.valid()
        formData = $forms.serializeArray()
        $hiddens = $parentForm.find('input[type=hidden].childForm')
        _.each(formData, (obj) ->
          $hidden = $hiddens.find("[name='#{obj.name}']")
          if $hidden.length == 0
            $hidden = $("<input type='hidden' name='#{obj.name}' class='childForm'/>")
            $parentForm.append($hidden)
            $hiddens.add($hidden) #prevent us from having duplicate names in a form, if we change this, remember that if the input exists in the parent form that behavior also needs changing
          $hidden.val(obj.value)
        )
        $parentForm.submit()
  )
)

requires:
underscore, jquery.validate