The Angular 1.2 way:

# By default, angular returns undefined for invalid attributes which removes
# the value from the form field's ngModel (which means it's not sent to the
# server, and old values would not be overwritten).
#
# This directive makes sure that form fields with an invalid value return an
# empty string instead of undefined.

for elementType in ['input', 'textarea', 'select']
  @app.directive elementType, ->

    priority: 1
    restrict: 'E'
    require: '?ngModel'

    link: (scope, element, attributes, ngModelController) ->
      return unless ngModelController

      if elementType == 'input'
        inputType = angular.lowercase(attributes.type)
        return if inputType == 'radio' || inputType == 'checkbox'

      ngModelController.$parsers.push (value) ->
        if ngModelController.$invalid && !value?
          ''
        else
          value

UI/UX Design by

We make sure that your target audience has the best possible experience with your digital product. You get:

• Design tailored to your audience
• Proven processes customized to your needs
• An expert team of experienced designers

Read more Show archive.org snapshot

In Angular 1.3, there's an allowInvalid option Show archive.org snapshot to allow invalid model values to be written to the ngModel.