ASP.NET MVC2 in Action 读书笔记 [9-2] CustomActionResults

Export.aspx:

<h2>Export</h2>
    <a href="<%=Url.Action("ExportUsers") %>">Export Users as CSV</a>

HomeController.cs:

[HandleError]
    public class HomeController : Controller
    {
        public ActionResult Index()
        {
            return View();
        }

        public ActionResult Export()
        {
            return View();
        }

        public ActionResult ExportUsers()
        {
            IEnumerable<User> model = UserRepository.GetUsers();
            return new CsvActionResult(model);
        }

        public ActionResult Logout()
        {
            return new LogoutActionResult(RedirectToAction("Index","Home"));
        }
    }

CsvActionResult.cs:

public class CsvActionResult : ActionResult
    {
        public IEnumerable ModelListing { get; set; }

        public CsvActionResult(IEnumerable modelListing)
        {
            ModelListing = modelListing;
        }

        public override void ExecuteResult(ControllerContext context)
        {
            byte[] data = new CsvFileCreator().AsBytes(ModelListing);

            var fileResult = new FileContentResult(data, "text/csv")
            {
                FileDownloadName = "CsvFile.csv"
            };

            fileResult.ExecuteResult(context);
        }
    }

CsvFileCreator.cs:

public class CsvFileCreator
    {
        public byte[] AsBytes(IEnumerable modelList)
        {
            StringBuilder sb = new StringBuilder();
            BuildHeaders(modelList, sb);
            BuildRows(modelList, sb);
            return sb.AsBytes();
        }

        private void BuildRows(IEnumerable modelList, StringBuilder sb)
        {
            foreach (object modelItem in modelList)
            {
                BuildRowData(modelList, modelItem, sb);
                sb.NewLine();
            }
        }

        private void BuildRowData(IEnumerable modelList, object modelItem, StringBuilder sb)
        {
            foreach (PropertyInfo info in modelList.GetType().GetElementType().GetProperties())
            {
                object value = info.GetValue(modelItem, new object[0]);
                sb.AppendFormat("{0},", value);
            }
        }

        private void BuildHeaders(IEnumerable modelList, StringBuilder sb)
        {
            foreach (PropertyInfo property in modelList.GetType().GetElementType().GetProperties())
            {
                sb.AppendFormat("{0},",property.Name);
            }
            sb.NewLine();
        }
    }

StringBuilderExtensions.cs:

public static class StringBuilderExtensions
    {
        public static void NewLine(this StringBuilder stringBuilder)
        {
            stringBuilder.Remove(stringBuilder.Length - 1, 1);
            stringBuilder.Append(Environment.NewLine);
        }
        public static byte[] AsBytes(this StringBuilder stringBuilder)
        {
            return stringBuilder.ToString().Select(c => Convert.ToByte((char) c)).ToArray();
        }
    }

UserRepository.cs:

public static class UserRepository
    {
        public static IEnumerable<User> GetUsers()
        {
            return new[]
                       {
                           new User
                               {
                                   FirstName = "Fred",
                                   LastName = "Flintstone",
                                   LastLogin = new DateTime(2010, 3, 22),
                                   Username = "FFlintstone"
                               },
                           new User
                               {
                                   FirstName = "Willma",
                                   LastName = "Flintstone",
                                   LastLogin = new DateTime(2010, 1, 1),
                                   Username = "WFlintstone"
                               },
                           new User
                               {
                                   FirstName = "Jack",
                                   LastName = "Flintstone",
                                   LastLogin = new DateTime(2010, 2, 2),
                                   Username = "JFlintstone"
                               },
                           new User
                               {
                                   FirstName = "Jane",
                                   LastName = "Flintstone",
                                   LastLogin = new DateTime(2010, 3, 3),
                                   Username = "JaFlintstone"
                               },
                       };
        }
    }

User.cs:

public class User
    {
        public string FirstName { get; set; }
        public string LastName { get; set; }
        public string Username { get; set; }
        public DateTime LastLogin { get; set; }
    }

LogoutActionResult.cs:

public class LogoutActionResult : ActionResult
    {
        public RedirectToRouteResult ActionAfterLogout { get; set; }

        public LogoutActionResult(RedirectToRouteResult actionAfterLogout)
        {
            ActionAfterLogout = actionAfterLogout;
        }

        public override void ExecuteResult(ControllerContext context)
        {
            FormsAuthentication.SignOut();
            ActionAfterLogout.ExecuteResult(context);
        }
    }