@workInProgress
@ngdoc overview
@name Cookbook: Advanced Form
@description

Here we extend the basic form example to include common features such as reverting, dirty state
detection, and preventing invalid form submission.

<doc:example>
<doc:source>
   <script>
   UserForm.$inject = ['$invalidWidgets'];
   function UserForm($invalidWidgets){
     this.$invalidWidgets = $invalidWidgets;
     this.state = /^\w\w$/;
     this.zip = /^\d\d\d\d\d$/;
     this.master = {
       name: 'John Smith',
       address:{
         line1: '123 Main St.',
         city:'Anytown',
         state:'AA',
         zip:'12345'
       },
       contacts:[
         {type:'phone', value:'1(234) 555-1212'}
       ]
     };
     this.cancel();
   }

   UserForm.prototype = {
     cancel: function(){
       this.form = angular.copy(this.master);
     },

     save: function(){
       this.master = this.form;
       this.cancel();
     }
   };
   </script>
   <div ng:controller="UserForm">

     <label>Name:</label><br/>
     <input type="text" name="form.name" ng:required/> <br/><br/>

     <label>Address:</label><br/>
     <input type="text" name="form.address.line1" size="33" ng:required/> <br/>
     <input type="text" name="form.address.city" size="12" ng:required/>,
     <input type="text" name="form.address.state" size="2" ng:required ng:validate="regexp:state"/>
     <input type="text" name="form.address.zip" size="5" ng:required
ng:validate="regexp:zip"/><br/><br/>

     <label>Contacts:</label>
     [ <a href="" ng:click="form.contacts.$add()">add</a> ]
     <div ng:repeat="contact in form.contacts">
       <select name="contact.type">
         <option>email</option>
         <option>phone</option>
         <option>pager</option>
         <option>IM</option>
       </select>
       <input type="text" name="contact.value" ng:required/>
        [ <a href="" ng:click="form.contacts.$remove(contact)">X</a> ]
     </div>
   <button ng:click="cancel()" ng:disabled="{{master.$equals(form)}}">Cancel</button>
   <button ng:click="save()" ng:disabled="{{$invalidWidgets.visible() ||
master.$equals(form)}}">Save</button>

   <hr/>
   Debug View:
   <pre>form={{form}}
   master={{master}}</pre>
   </div>
</doc:source>
<doc:scenario>
  it('should enable save button', function(){
    expect(element(':button:contains(Save)').attr('disabled')).toBeTruthy();
    input('form.name').enter('');
    expect(element(':button:contains(Save)').attr('disabled')).toBeTruthy();
    input('form.name').enter('change');
    expect(element(':button:contains(Save)').attr('disabled')).toBeFalsy();
    element(':button:contains(Save)').click();
    expect(element(':button:contains(Save)').attr('disabled')).toBeTruthy();
  });
  it('should enable cancel button', function(){
    expect(element(':button:contains(Cancel)').attr('disabled')).toBeTruthy();
    input('form.name').enter('change');
    expect(element(':button:contains(Cancel)').attr('disabled')).toBeFalsy();
    element(':button:contains(Cancel)').click();
    expect(element(':button:contains(Cancel)').attr('disabled')).toBeTruthy();
    expect(element(':input[name=form.name]').val()).toEqual('John Smith');
  });
</doc:scenario>
</doc:example>


#Things to notice

* Cancel & save buttons are only enabled if the form is dirty — there is something to cancel or
save.
* Save button is only enabled if there are no validation errors on the form.
* Cancel reverts the form changes back to original state.
* Save updates the internal model of the form.
* Debug view shows the two models. One presented to the user form and the other being the pristine
copy master.
