I have code like this, where the commit is done at the end of the line. the goal is that when an error occurs while sending an email, then the commit will not be performed but will rollback. is something like this a good thing? or is there a better way than the one I'm currently implementing?
public async Task<IActionResult> Register(RegisterAccount register)
{
MyAccount myAccount = new();
using var transaction = _dbContext.Database.BeginTransaction();
bool afterRegister = false;
try
{
//code for check account
//code for set value register account
afterRegister = true;
_dbContext.Database.OpenConnection();
transaction.CreateSavepoint("register");
_dbContext.MyAccounts.Add(myAccount);
await _dbContext.SaveChangesAsync();
_dbContext.Database.CloseConnection();
//code for send email
transaction.Commit();
return RedirectToAction("RegisterConfirm", "Account", new { emailConfirm = myAccount.Email });
}
catch(Exception e)
{
if (afterRegister)
{
transaction.RollbackToSavepoint("register");
}
return View();
}
}
thank you for answering my question. good luck always
Related
Hello StackOverflow community,
I know there's a lot of code in this post, but I wanted to give you guys, the community as good of a picture as possible as to what is going on here so that maybe someone can help me figure out what my issue is.
Recently for a project I'm working on we've decided to upgrade from MvvmCross 5.7.0 to 6.2.2. I've managed to get our UWP app to successfully complete the initialization and setup process. The first viewmodel for which we register the app start also starts initializing. However, I'm finding that my vm initialization hangs at a particular line of code (shown in the code below). The weirdest part though is similar methods called in the app initialization code run perfectly fine without hanging/deadlock, so I'm not sure what's different Here's a simplified version of my viewmodel code to illustrate:
public class MyViewModel : BaseAuthenticatedTabBarViewModel, IMvxViewModel<int>
{
private int? _settingValue;
public override async Task Initialize()
{
//Some irrelevant initialization code
Exception e = null;
try
{
//This line of code never returns
_settingValue = _settingValue ?? await AppSettingService.GetSettingValue();
}
catch (Exception ex)
{
e = ex;
}
if (e != null)
{
await HandleCatastrophicError(e);
}
}
}
The AppSettingService.GetSettingValue() method looks like this:
public async Task<int?> GetCurrentEventId()
{
return await GetNullableIntSetting("SettingValue");
}
private static async Task<int?> GetNullableIntSetting(string key)
{
try
{
var setting = await SettingDataService.SettingByName(key);
if (setting != null)
{
return string.IsNullOrEmpty(setting.Value) ? (int?)null : Convert.ToInt32(setting.Value);
}
}
catch (Exception ex)
{
//Handle the exception
}
return null;
}
All the code for SettingDataService:
public class SettingDataService : DataService<SettingDataModel>, ISettingDataService
{
public async Task<SettingDataModel> SettingByName(string name)
{
try
{
var values = (await WhereAsync(e => e.Name == name));
return values.FirstOrDefault();
}
catch(Exception ex)
{
//Handle the exception
}
return null;
}
}
Finally, the implementation for WhereAsync() is in a class called DataService and is as follows:
public virtual async Task<IEnumerable<T>> WhereAsync(System.Linq.Expressions.Expression<Func<T, bool>> condition, SQLiteAsyncConnection connection = null)
{
return await (connection ?? await GetConnectionAsync())
.Table<T>()
.Where(condition)
.ToListAsync();
}
Thank you very much for your help in advance
Edit: Forgot to also add this crucial bit of code to help you guys even further:
protected async Task<SQLiteAsyncConnection> GetConnectionAsync()
{
SQLiteAsyncConnection connection = null;
while (true)
{
try
{
connection = Factory.Create(App.DatabaseName);
// This line of code is the culprit. For some reason this hangs and I can't figure out why.
await connection.CreateTableAsync<T>();
break;
}
catch (SQLiteException ex)
{
if (ex.Result != Result.CannotOpen && ex.Result != Result.Busy && ex.Result != Result.Locked)
{
throw;
}
}
await Task.Delay(20);
}
return connection;
}
I'm suspecting that you are calling Task.Wait or Task<T>.Result somewhere further up your call stack. Or if you're not doing it, MvvmCross is probably doing it for you. This will cause a deadlock when called from a UI context.
Personally, I prefer the approach that ViewModels should always be constructed synchronously, and cannot have an asynchronous "initialization". That is, they must construct themselves (synchronously) into a "loading" state, and this construction can kick off an asynchronous operation that will later update them into a "loaded" state. The synchronous-initialization pattern means there's never an unnecessary delay when changing views; your users may only see a spinner or a loading message, but at least they'll see something. See my article on async MVVM data binding for a pattern that helps with this, and note that there's a newer version of the helper types in that article.
Hi I wrote the following code:
private bool GetIsCompleted()
{
return Email.SendMessageAsync().IsCompletedSuccessfully;
}
[HttpPost]
public ViewResult CheckOut(Order order)
{
if (Cart.Lines.Count() == 0)
{
ModelState.AddModelError("","Your Cart is empty!");
}
if (ModelState.IsValid)
{
order.CartLines = Cart.Lines;
order.DateTime = DateTime.Now;
order.TotalPrice = Cart.ComputeTotalValue();
if (Repository.SaveOrder(order))
{
if (User.Identity.Name != null)
{
Email.SetMessageBody(order.OrderID);
if (GetIsCompleted())
{
Cart.Clear();
return View("Completed");
}
}
}
ViewBag.Error = "An error Occured while sending you an email with the order details.";
return View(new Order());
}
else
{
ViewBag.Error = "An error Occured while trying to save your order. Please try again!";
return View(new Order());
}
}
public async Task SendMessageAsync()
{
this.Message = new MailMessage(this.MailFrom.ToString(), this.MailTo.ToString(), this.GetSubject(), this.GetMessageBody());
//Message.Dispose();
try
{
await this.Client.SendMailAsync(this.Message);
}
catch (Exception ex)
{
Logger.LogInformation("The Email couldn't send to the recipient");
}
}
I get
An error Occured while sending you an email with the order details.
in the View. I want GetIsCompleted() to return true to proceed the code. It is developed under .net core. I do not understand why IsCompletedSuccessfully() does not return true; Any suggestion?
The current flow of your code is this:
Start sending the e-mail.
Check if it is completed successfully, decide that it hasn't and return failure.
The e-mail completes sending.
You're awaiting the actual SendMailAsync(..) method, and that's great, but nothing awaits SendMessageAsync(...) so it immediately returns the incomplete task to the caller. Because there isn't enough time between starting to send the e-mail and checking if the task completed, the status will be false.
You need to use async all the way up. Change your method definition to be async:
public async Task<ViewResult> CheckOut(Order order)
Replace this code:
if (GetIsCompleted())
{
Cart.Clear();
return View("Completed");
}
with this:
try
{
await Email.SendMessageAsync();
Cart.Clear();
return View("Completed");
}
catch (Exception e)
{
// handle exception
}
It's worth noting that you'll only ever get an exception if the call to new MailMessage(...) fails because your try/catch block in SendMessageAsync is swallowing all other exceptions.
I built a module into my MVC site that allows administrators to create, modify and delete website users. However, I can not seem to update user information via the following code:
[HttpPost]
public ActionResult Edit(User user)
{
if (ModelState.IsValid)
{
try
{
//CHANGE EXISTING USER
MembershipUser siteUser = Membership.GetUser(user.Username);
siteUser.Email = user.Email;
siteUser.IsApproved = true;
siteUser.Comment = "User Update on " + DateTime.UtcNow;
siteUser.UnlockUser();
Membership.UpdateUser(siteUser);
if (!String.IsNullOrEmpty(user.Password))
{
siteUser.ChangePassword(siteUser.GetPassword(), user.Password);
}
unitOfWork.UsersRepository.Update(user);
unitOfWork.Save();
return RedirectToAction("Index");
}
catch (Exception err)
{
// CODE REMOVED FOR BREVITY
}
}
return View(user);
}
Any suggestions?
After further testing, it would appear that one line was causing the user information to reset.
siteUser.UnlockUser();
This line can not be called prior to saving user alterations via Membership.UpdateUser() or the changes will be lost. Hopefully this saves somebody some head scratching.
I am adding a user to my aspnetusers database and that is working fine. Then I am also trying to link them to an existing role. That is when I get the error: "An asynchronous module or handler completed while an asynchronous operation was still pending."
Here is my method with the problem code:
private async void checkOldDB(string email, string password)
{
bool isValidUser = false;
ReportsMvc.App_Code.BLL.FUN.cFunUser user = ReportsMvc.App_Code.DAL.FUN.cFunUserDB.getUser(email);
if (user != null)
{
isValidUser = PasswordHash.PasswordHash.ValidatePassword(password, user.Password);
if (!isValidUser)
{
isValidUser = PasswordHash.PasswordHash.ValidateHashes(password, user.Password);
}
}
if (isValidUser)
{
var user2 = new ApplicationUser { UserName = email, Email = email };
var result = await UserManager.CreateAsync(user2, password);
if (result.Succeeded)
{
string role = user.Role;
if (string.IsNullOrEmpty(role))
{
role = "User";
}
UserManager.AddToRole(user2.Id, role);
await SignInManager.SignInAsync(user2, isPersistent: false, rememberBrowser: false);
}
}
}
The line starting with "await SignInManager" was working fine. Then when I added in that code to AddToRole, I started getting the above error. This identity/authentication stuff is all very new to me.
You should change async void to async Task and await it where you call it.
As a general rule, you should avoid async void; it should only be used for event handlers. I describe this more in an MSDN article.
I have been experimenting with WP7 apps today and have hit a bit of a wall.
I like to have seperation between the UI and the main app code but Ive hit a wall.
I have succesfully implemented a webclient request and gotten a result, but because the call is async I dont know how to pass this backup to the UI level. I cannot seem to hack in a wait for response to complete or anything.
I must be doing something wrong.
(this is the xbox360Voice library that I have for download on my website: http://www.jamesstuddart.co.uk/Projects/ASP.Net/Xbox_Feeds/ which I am porting to WP7 as a test)
here is the backend code snippet:
internal const string BaseUrlFormat = "http://www.360voice.com/api/gamertag-profile.asp?tag={0}";
internal static string ResponseXml { get; set; }
internal static WebClient Client = new WebClient();
public static XboxGamer? GetGamer(string gamerTag)
{
var url = string.Format(BaseUrlFormat, gamerTag);
var response = GetResponse(url, null, null);
return SerializeResponse(response);
}
internal static XboxGamer? SerializeResponse(string response)
{
if (string.IsNullOrEmpty(response))
{
return null;
}
var tempGamer = new XboxGamer();
var gamer = (XboxGamer)SerializationMethods.Deserialize(tempGamer, response);
return gamer;
}
internal static string GetResponse(string url, string userName, string password)
{
if (!string.IsNullOrEmpty(userName) && !string.IsNullOrEmpty(password))
{
Client.Credentials = new NetworkCredential(userName, password);
}
try
{
Client.DownloadStringCompleted += ClientDownloadStringCompleted;
Client.DownloadStringAsync(new Uri(url));
return ResponseXml;
}
catch (Exception ex)
{
return null;
}
}
internal static void ClientDownloadStringCompleted(object sender, DownloadStringCompletedEventArgs e)
{
if (e.Error == null)
{
ResponseXml = e.Result;
}
}
and this is the front end code:
public void GetGamerDetails()
{
var xboxManager = XboxFactory.GetXboxManager("DarkV1p3r");
var xboxGamer = xboxManager.GetGamer();
if (xboxGamer.HasValue)
{
var profile = xboxGamer.Value.Profile[0];
imgAvatar.Source = new BitmapImage(new Uri(profile.ProfilePictureMiniUrl));
txtUserName.Text = profile.GamerTag;
txtGamerScore.Text = int.Parse(profile.GamerScore).ToString("G 0,000");
txtZone.Text = profile.PlayerZone;
}
else
{
txtUserName.Text = "Failed to load data";
}
}
Now I understand I need to place something in ClientDownloadStringCompleted but I am unsure what.
The problem you have is that as soon as an asynchronous operation is introduced in to the code path the entire code path needs to become asynchronous.
Because GetResponse calls DownloadStringAsync it must become asynchronous, it can't return a string, it can only do that on a callback
Because GetGamer calls GetResponse which is now asynchronous it can't return a XboxGamer, it can only do that on a callback
Because GetGamerDetails calls GetGamer which is now asynchronous it can't continue with its code following the call, it can only do that after it has received a call back from GetGamer.
Because GetGamerDetails is now asynchronous anything call it must also acknowledge this behaviour.
.... this continues all the way up to the top of the chain where a user event will have occured.
Here is some air code that knocks some asynchronicity in to the code.
public static void GetGamer(string gamerTag, Action<XboxGamer?> completed)
{
var url = string.Format(BaseUrlFormat, gamerTag);
var response = GetResponse(url, null, null, (response) =>
{
completed(SerializeResponse(response));
});
}
internal static string GetResponse(string url, string userName, string password, Action<string> completed)
{
WebClient client = new WebClient();
if (!string.IsNullOrEmpty(userName) && !string.IsNullOrEmpty(password))
{
client.Credentials = new NetworkCredential(userName, password);
}
try
{
client.DownloadStringCompleted += (s, args) =>
{
// Messy error handling needed here, out of scope
completed(args.Result);
};
client.DownloadStringAsync(new Uri(url));
}
catch
{
completed(null);
}
}
public void GetGamerDetails()
{
var xboxManager = XboxFactory.GetXboxManager("DarkV1p3r");
xboxManager.GetGamer( (xboxGamer) =>
{
// Need to move to the main UI thread.
Dispatcher.BeginInvoke(new Action<XboxGamer?>(DisplayGamerDetails), xboxGamer);
});
}
void DisplayGamerDetails(XboxGamer? xboxGamer)
{
if (xboxGamer.HasValue)
{
var profile = xboxGamer.Value.Profile[0];
imgAvatar.Source = new BitmapImage(new Uri(profile.ProfilePictureMiniUrl));
txtUserName.Text = profile.GamerTag;
txtGamerScore.Text = int.Parse(profile.GamerScore).ToString("G 0,000");
txtZone.Text = profile.PlayerZone;
}
else
{
txtUserName.Text = "Failed to load data";
}
}
As you can see async programming can get realy messy.
You generally have 2 options. Either you expose your backend code as an async API as well, or you need to wait for the call to complete in GetResponse.
Doing it the async way would mean starting the process one place, then return, and have the UI update when data is available. This is generally the preferred way, since calling a blocking method on the UI thread will make your app seem unresponsive as long as the method is running.
I think the "Silverlight Way" would be to use databinding. Your XboxGamer object should implement the INotifyPropertyChanged interface. When you call GetGamer() it returns immediately with an "empty" XboxGamer object (maybe with GamerTag=="Loading..." or something). In your ClientDownloadStringCompleted handler you should deserialize the returned XML and then fire the INotifyPropertyChanged.PropertyChanged event.
If you look at the "Windows Phone Databound Application" project template in the SDK, the ItemViewModel class is implemented this way.
Here is how you can expose asynchronous features to any type on WP7.