Solution 1:

Nice solution by leocaseiro

<input class="ng-hide" id="input-file-id" multiple type="file" />
<label for="input-file-id" class="md-button md-raised md-primary">Choose Files</label>

enter image description here

View in codepen

Solution 2:

For Angular 6+:

HTML:

<input #csvInput hidden="true" type="file" onclick="this.value=null" (change)="csvInputChange($event)" accept=".csv"/>
<button mat-flat-button color="primary" (click)="csvInput.click()">Choose Spreadsheet File (CSV)</button>

Component method:

  csvInputChange(fileInputEvent: any) {
    console.log(fileInputEvent.target.files[0]);
  }

Note: This filters to just allow .csv files.

Solution 3:

Another example of the solution. Will look like the following enter image description here

CodePen link there.

  <choose-file layout="row">
    <input id="fileInput" type="file" class="ng-hide">
    <md-input-container flex class="md-block">
      <input type="text" ng-model="fileName" disabled>
      <div class="hint">Select your file</div>
    </md-input-container>
    <div>
      <md-button id="uploadButton" class="md-fab md-mini">
        <md-icon class="material-icons">attach_file</md-icon>
      </md-button>
    </div>
  </choose-file>   

.directive('chooseFile', function() {
    return {
      link: function (scope, elem, attrs) {
        var button = elem.find('button');
        var input = angular.element(elem[0].querySelector('input#fileInput'));

        button.bind('click', function() {
          input[0].click();
        });

        input.bind('change', function(e) {
          scope.$apply(function() {
            var files = e.target.files;
            if (files[0]) {
              scope.fileName = files[0].name;
            } else {
              scope.fileName = null;
            }
          });
        });
      }
    };
  });

Hope it helps!

Solution 4:

Based on this answer. It took some time for me to make this approach working, so I hope my answer will save someone's time.

DEMO on CodePen

Directive:

angular.module('app').directive('apsUploadFile', apsUploadFile);

function apsUploadFile() {
    var directive = {
        restrict: 'E',
        templateUrl: 'upload.file.template.html',
        link: apsUploadFileLink
    };
    return directive;
}

function apsUploadFileLink(scope, element, attrs) {
    var input = $(element[0].querySelector('#fileInput'));
    var button = $(element[0].querySelector('#uploadButton'));
    var textInput = $(element[0].querySelector('#textInput'));

    if (input.length && button.length && textInput.length) {
        button.click(function (e) {
            input.click();
        });
        textInput.click(function (e) {
            input.click();
        });
    }

    input.on('change', function (e) {
        var files = e.target.files;
        if (files[0]) {
            scope.fileName = files[0].name;
        } else {
            scope.fileName = null;
        }
        scope.$apply();
    });
}

upload.file.template.html

<input id="fileInput" type="file" class="ng-hide">
<md-button id="uploadButton"
           class="md-raised md-primary"
           aria-label="attach_file">
    Choose file
</md-button>
<md-input-container md-no-float>
    <input id="textInput" ng-model="fileName" type="text" placeholder="No file chosen" ng-readonly="true">
</md-input-container>