http://embed.plnkr.co/keaGc3Y4Pmgfs04HJgnC/
Here is the link of my code.I am trying to validate my upload by disabling the load data button when the file is empty. It is working for the first time,but when the next time I upload the file,ng-change is not working and the button is still showing disabled although I have uploaded the next file. I am a beginner in AngularJS,so i might be doing some basic mistake.please help.
Since you are trying to upload the same file again, the onChange event will not fire, because it is the same file. To resolve this issue, you need to unset the input field after you uploaded the file. Unfortunately, you have to use jQuery (or get the element wit vanilla js) for this. So, in your onFileLoad function you could do something like this:
angular.element("input[type='file']").val(null); // Unset Input
$scope.filename = undefined; // Unset $scope property
Note that this is not the "angular" way of doing this. It would be better to move this into a directive, cause you should not manipulate the DOM within a Controller.
Update:
As said before, you need to include jQuery for this to work. Angular's jqLite does not support selecting DOM elements by its type. So, either you include jQuery (needs to be loaded before angular!) or you modify the code so you can use vanilla JS or jqlite.