Exemplo nestend_attributes com rails

protocolo.js

$("#tipo_doc").change(function() {
  let id = this.value;
  $("#campos").html(" ")
  $.ajax({
    headers: {
      'X-CSRF-Token': $('meta[name="csrf-token"]').attr('content')
    },
    url: '/protocolos/campos',
    type: 'POST',
    dataType: 'json',
    data: { "tipo_documento" : id },
    success: function(response) {
      response.forEach(function(element) {
        let numeroRand = 1000 + Math.floor(Math.random() * 10000);
        $("#campos").append('<p><label>' + element + '</label></p><input type="text" name="protocolo[protocolo_campos_attributes]['+numeroRand+'][tipo]" id="'+element+'" />')
      });
    }
  });
});