http://discuss.emberjs.com/t/how-to-communicate-to-child-components/7772

field-component.hbs

{{input value=field.value key-press="updateValue"}}

{{#if isFieldDirty}}
  Field is dirty
{{/if}}

field-component.js

import Ember from 'ember';

export default Ember.Component.extend({
  field: null,
  
  isFieldDirty: Ember.computed('field.value', {
    get() {
      return this.get('field.value') !== this.get('field.originalValue')
    }
  })
  
  actions: {
    updateValue(newValue) {
      this.get('onFieldValueChange')(newValue);
    }
  }
});

form-component.hbs

{{#each fields as |field|}}
  {{field-component field=field onFieldValueChange=(mut field.value)}}
{{/each}}

form-component.js

import Ember from 'ember';

export default Ember.Component.extend({
  fields: Ember.computed({
    get() {
      return [
        {name: 'id', value: 'id', originalValue: 'id'},
        {name: 'username', value: 'username', originalValue: 'username'},
      ]
    }
  })
  
  actions: {
    reset() {
      //reset all the fields to make value === originalValue
    }
  }
});
Raw