如果在Laravel中使用JQuery存在记录，则显示消息警报

Question

有人可以帮我解决这个问题。我有一个控制器，它首先检查记录是否存在。如果记录存在，它应该返回页面并抛出模态消息或js警报。我在使用JQuery时遇到了麻烦，因为我对此并不熟悉。这是我下面的代码;

Public function postInsert_enroll(Request $r)
{
    $area_code = Input::get ( 'area_code' );
    $sy = Input::get ( 'sy' );
    $semester = Input::get ( 'semester' );
    $college = Input::get ( 'college' );
    $tot_enroll = Input::get ( 'tot_enroll' );
    $gender = Input::get ( 'gender' );
    $remarks = Input::get ( 'remarks' );

            if (Enroll::where('area_code', '=', $area_code)
                ->where('sy', '=', $sy)
                ->where('semester', '=', $semester)
                ->where('gender', '=', $gender)
                ->where('college', '=', $college)
                ->exists())
            {
               return response()->json(['errors'=>errors()]);
            }else
            {
            $enrollments = new Enroll();
            $enrollments->area_code = $r->area_code;
            $enrollments->sy = $r->sy;
            $enrollments->semester = $r->semester;
            $enrollments->college = $r->college;
            $enrollments->tot_enroll = $r->tot_enroll;
            $enrollments->gender = $r->gender;
            $enrollments->remarks = $r->remarks;
            $enrollments->r_status = 'A';
            $enrollments->save();
            return response()->json($enrollments);
            }
}

在我的情况下，如果记录不存在，它会继续回到我的JQuery并保存记录，并附加模态消息，但是当记录存在时，记录没有保存但没有任何反应，没有模态消息弹出说记录已经存在。

这是我的JQuery：

          $.ajax({
          url: '/postInsert_enroll',
          type: 'post',
          data: {
            '_token': $('input[name=_token]').val(),
            'area_code': $('select[name=area_code]').val(),
            'sy': $('select[name=sy]').val(),
            'semester': $('select[name=semester]').val(),
            'college': $('select[name=college]').val(),
            'tot_enroll': $('input[name=tot_enroll]').val(),
            'gender': $('select[name=gender]').val(),
            'remarks': $('input[name=remarks]').val()
          },
          success: function(data) {
            if (data.errors) {
              $('.error').removeClass('hidden');
              $('.error').text(data.errors.area_code);
              $('.error').text(data.errors.sy);
              $('.error').text(data.errors.semester);
              $('.error').text(data.errors.college);
              $('.error').text(data.errors.tot_enroll);
              $('.error').text(data.errors.gender);
              $('.error').text(data.errors.remarks);
              $('#messcontent').text('Error. Record has not been saved.');
              $('#messModal').modal('show');
            } else {
              $('.error').remove();
              $('#enrolltable').append("<tr class='items" + data.id + "' id='" + data.id + "'><td><input type='checkbox' id='chkrows' name='chkrows' class='checkitem' value='" + data.id + "'></td><td>" + data.id + "</td><td>" + data.area_code + "</td><td>" + data.sy + "</td><td>" + data.semester + "</td><td>" + data.college + "</td><td>" + data.gender + "</td><td>" + data.tot_enroll + "</td><td  class='enroll-buttons'><a href='#' class='show_enroll btn btn-space' onclick='enroll_show();'><span class='glyphicon glyphicon-eye-open'></span> Show </a><a href='#' class='edit_enroll btn btn-space' onclick='enroll_edit();'><span class='glyphicon glyphicon-edit'></span> Edit </a><a href='#' class='delete-enroll btn btn-space' onclick='enroll_delete();'><span class='glyphicon glyphicon-trash'></span> Delete</button></td></tr>");

            $('#messModal').delay(1000).fadeOut(450);
            $('#messcontent').text('New enrollment record saved.');
            $('#messModal').modal('show');
            setTimeout(function(){$('#messModal').modal('hide');}, 1500);
            }
          },
        });