using input type file with angular material 2

You need to simply trigger the click for your file input.

<button md-mini-fab type="button" onclick="document.getElementById('fileToUpload').click()">
  <label for="fileToUpload"><md-icon>add</md-icon></label>
</button>
<input id="fileToUpload" type="file" style="display:none;">

Here is a simple solution:

<button (click)="fileInput.click()">
  <md-icon>library_add</md-icon>
  <span>Select</span>
  <input #fileInput type="file" (change)="onFileInput($event)" style="display:none;" />
</button>

I'm not sure about your cases, but in my Angular5 application I used this HTML structure for uploading files on server:

<label for="uploadPicture" class="upload-file">
   <mat-icon>add_a_photo</mat-icon>
</label>
<input type="file"
       id="uploadPicture"
       class="hidden-input"
       accept="image/jpeg, .jpeg, image/png, .png, image/pjpeg, .jpg"
       (change)="selectFile($event.target.files[0])">

In my case this solution working great. No need to trigger click event, because when you click on <label> that related to input it's same as click on input.

Try this:

<input #file type="file" [hidden]="true" accept="image/*" (change)="upload(file.files)">
<button mat-button #upload (click)="file.click()">Upload file</button>

<mat-button> is from https://material.angular.io

We are hiding the basic input button and linking the material button to the file upload.