Random Selection in Quiz -> Question Child table


I am using Client Script in the Education Module to do the following:

1- Add a custom button to the Quiz creation page.

2- upon clicking the button a dialog with 2 inputs. first is the question category (class) and the second for the number of questions required.

3- when I click submit I need the function to randomly choose the selected number of questions that have the same question category or class selected in the dialog.

the blow code is the dialog code:

    frappe.ui.form.on('Quiz', {
    refresh: function(frm) {
        frm.add_custom_button(__("Get Questions from Bank"), function() {

function show_question_dialog(frm) {
      {'fieldname': 'quiz_question', 'fieldtype': 'Link', 'label': 'Question Class', 'reqd': 1, 'options': 'Question Class'} ,
      {'fieldname': 'question_count', 'fieldtype': 'Int', 'label': 'Questions Count', 'reqd': 1 }  
   'Get Questions from Bank',
   'Get Questions'

Any idea how should I start the fetching action and add it to the “Quiz Question” child table.