how can i trigger the click event of another element in ng-click using angularjs?

So it was a simple fix. Just had to move the ng-click to a scope click handler:

<input id="upload"
    type="file"
    ng-file-select="onFileSelect($files)"
    style="display: none;">

<button type="button"
    ng-click="clickUpload()">Upload</button>



$scope.clickUpload = function(){
    angular.element('#upload').trigger('click');
};

I had this same issue and this fiddle is the shizzle :) It uses a directive to properly style the file field and you can even make it an image or whatever.

goto this link  http://jsfiddle.net/stereosteve/v5Rdc/7/

If your input and button are siblings (and they are in your case OP):

<input id="upload"
    type="file"
    ng-file-select="onFileSelect($files)"
    style="display: none;">

<button type="button" uploadfile>Upload</button>

Use a directive to bind the click of your button to the file input like so:

app.directive('uploadfile', function () {
    return {
      restrict: 'A',
      link: function(scope, element) {

        element.bind('click', function(e) {
            angular.element(e.target).siblings('#upload').trigger('click');
        });
      }
    };
});

Simply have them in the same controller, and do something like this:

HTML:

<input id="upload"
    type="file"
    ng-file-select="onFileSelect($files)"
    style="display: none;">

<button type="button"
    ng-click="startUpload()">Upload</button>

JS:

var MyCtrl = [ '$scope', '$upload', function($scope, $upload) {
  $scope.files = [];
  $scope.startUpload = function(){
    for (var i = 0; i < $scope.files.length; i++) {
      $upload($scope.files[i]);
    } 
  }
  $scope.onFileSelect = function($files) {
     $scope.files = $files;
  };
}];

This is, in my opinion, the best way to do it in angular. Using jQuery to find the element and trigger an event isn't the best practice.

The solution, as pointed out by other answers, is to use

angular.element(element).trigger(event);

Here's an example of how I randomly select multiple select elements:

$scope.randomize = function(){
    var games = [].slice.call(document.querySelectorAll('.games select'));

    games.forEach(function(e){
        // Logically change the element (Angular won't know about this)
        e.selectedIndex = parseInt(Math.random() * 100, 10) < 50 ? 1 : 2;

        // Manually tell Angular that the DOM has changed
        angular.element(e).trigger('change');
    });
};

I just came across this problem and have written a solution for those of you who are using Angular. You can write a custom directive composed of a container, a button, and an input element with type file. With CSS you then place the input over the custom button but with opacity 0. You set the containers height and width to exactly the offset width and height of the button and the input's height and width to 100% of the container.

the directive

angular.module('myCoolApp')
  .directive('fileButton', function () {
    return {
      templateUrl: 'components/directives/fileButton/fileButton.html',
      restrict: 'E',
      link: function (scope, element, attributes) {

        var container = angular.element('.file-upload-container');
        var button = angular.element('.file-upload-button');

        container.css({
            position: 'relative',
            overflow: 'hidden',
            width: button.offsetWidth,
            height: button.offsetHeight
        })

      }

    };
  });

a jade template if you are using jade

div(class="file-upload-container") 
    button(class="file-upload-button") +
    input#file-upload(class="file-upload-input", type='file', onchange="doSomethingWhenFileIsSelected()")  

the same template in html if you are using html

<div class="file-upload-container">
   <button class="file-upload-button"></button>
   <input class="file-upload-input" id="file-upload" type="file" onchange="doSomethingWhenFileIsSelected()" /> 
</div>

the css

.file-upload-button {
    margin-top: 40px;
    padding: 30px;
    border: 1px solid black;
    height: 100px;
    width: 100px;
    background: transparent;
    font-size: 66px;
    padding-top: 0px;
    border-radius: 5px;
    border: 2px solid rgb(255, 228, 0); 
    color: rgb(255, 228, 0);
}
.file-upload-input {
    position: absolute;
    top: 0;
    left: 0;
    z-index: 2;
    width: 100%;
    height: 100%;
    opacity: 0;
    cursor: pointer;
}

If you are getting $scope binding errors make sure you wrap the click event code on a setTimeout Function.

VIEW

<input id="upload"
    type="file"
    ng-file-select="onFileSelect($files)"
    style="display: none;">

<button type="button"
    ng-click="clickUpload()">Upload</button>

CONTROLLER

$scope.clickUpload = function(){
    setTimeout(function () {
      angular.element('#upload').trigger('click');
    }, 0);
};

I think you are over complicated things a bit. Do you really need to trigger a click on the input from your button ?

I suggest you just apply a proper style to your input and the ngFileSelect directive will do the rest and call your onFileSelect function whenever a file is submitted :

input.file {
    cursor: pointer;
    direction: ltr;
    font-size: 23px;
    margin: 0;
    opacity: 0;
    position: absolute;
    right: 0;
    top: 0;
    transform: translate(-300px, 0px) scale(4);
}