how can i set the number of files that can be uploaded in a flask?

Below is the code to handle the file limit from backend:

@app.route('/upload', methods=["POST","GET"])
 def upload():
  if request.method == "POST" and 'photo' in request.files:
    uploaded_photos = request.files.getlist('photo')
    if len(uploaded_photos) > 2:
      error = "You are only allowed to upload a maximum of 2 files"
      return render_template("upload.html", error=error)
    else:
      for photo in uploaded_photos:
        photos.save(photo)
      return 'saved'
  else:
    return render_template("upload.html")

Need to specify multiple attribute in the input field of the file to allow multiple images to be uploaded at a time

{% if error %}
  <p class=error><strong>Error:</strong> {{ error }}</p>
{% endif %}
<form action="upload" method="POST" enctype="multipart/form-data">  
  <div class="custom-file">
    <label for="customFile">Choose Cover Photo --Optional--</label>
    <br>
    <input type="file" name="photo" id="customFile" multiple>
    <input type = "submit" value = "submit">
  </div>
</form>

You can handle it in frontend using jquery. Below is the code.

$(function(){
   $("input[type = 'submit']").click(function(){
    var $fileUpload = $("input[type='file']");
     if (parseInt($fileUpload.get(0).files.length) > 2){
       alert("You are only allowed to upload a maximum of 2 files");
     }
  });
});

<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<form action="#" method="POST" enctype="multipart/form-data">  
  <div class="custom-file">
    <label for="customFile">Choose Cover Photo --Optional--</label>
    <br>
    <input type="file" name="photo" id="customFile" multiple>
    <input type = "submit" value = "submit">
  </div>
</form>