public async Task <IActionResult> OnPostGroupsAsync() { MemoryStream stream = new MemoryStream(); await Request.Body.CopyToAsync(stream); stream.Position = 0; using StreamReader reader = new StreamReader(stream); var requestBody = reader.ReadToEnd(); if (requestBody.Length > 0) { var departmentId = Guid.Parse(requestBody); IEnumerable <SelectListItem> groupsAsSelectList = await _dropDownService.GetGroups(departmentId); return(new JsonResult(groupsAsSelectList)); } return(null); }