[HttpPost]
        public ActionResult Edit(string member)
        {
            ...
        }

$.ajax({
                        url: '/Data/Edit',
                        type: 'post',
                        dataType: 'json',
                        data: JSON.stringify(self.member()),
                        contentType: 'application/json',
                        success: function(result) {
                            if (result.success == true) {
                                alert("Успешно!");
                                window.location.href = '/Data/' + @Html.Raw(entityId);
                            } else {
                                alert(result.resultText);
                            }
                        },
                        error: function(XMLHttpRequest, textStatus, errorThrown) {
                            alert(textStatus);
                        }

data: JSON.stringify({ member: JSON.stringify(self.member()) })