[AngularJS] 如何使用form validation驗證input=file

原生的ng並不支援file element的validation，可透過自已新增directive來達到這個功能。

可以參考這篇StackoverFlow: http://stackoverflow.com/questions/16207202/required-attribute-not-working-with-file-input-in-angular-js

directive

app.directive('validFile',function(){
  return {
    require:'ngModel',
    link:function(scope,el,attrs,ngModel){
      //change event is fired when file is selected
      el.bind('change',function(){
        scope.$apply(function(){
          ngModel.$setViewValue(el.val());
          ngModel.$render();
        });
      });
    }
  }
});

HTML

    
    

Input is valid: {{myForm.userUpload.$valid}}
      
Selected file: {{filename}}