disabled-field.hbs

<element tagName='input' value={{value}}>
{{!-- I should have added `disabled={{disabled}}` but how do I know that? --}}

disabled-field.js

export Ember.Component.extend(DisabledMixin, {
  value: 'invalid'
});

disabled-mixin.js

export Ember.Mixin.create({
  attributeBindings: 'disabled',

  disabled: function(){
    return this.get('value') === 'invalid';
  }.property()
});