public async Task <BankUserUpdateModel> Deposit(int id, decimal amount, byte[] accountTimestamp)
{
var updateStateModel = new BankUserUpdateModel();
if (amount <= 0)
{
updateStateModel.ErrorList.Add("DepositeAmount", "The amount must be larger than 0.");
updateStateModel.ErrorList.Add(string.Empty, "Unable to save changes.");
return(updateStateModel);
}
var accountToUpdate = await this.GetAccountById(id);
if (accountToUpdate == null)
{
updateStateModel.ErrorList.Add(string.Empty, "Unable to save changes. The account was deleted by another user.");
return(updateStateModel);
}
// deposit the amount into Account
accountToUpdate.Balance = accountToUpdate.Balance + amount;
// set the Timestamp value for the retrieved Account. This Timestamp value will be compared to detech concurrence issue
_context.Entry(accountToUpdate).Property("Timestamp").OriginalValue = accountTimestamp;
try
{
await _context.SaveChangesAsync();
}
catch (DbUpdateConcurrencyException ex)
{
updateStateModel.ErrorList.Add(string.Empty, "The record you attempted to edit was modified by another user after you got the original value.");
var exceptionEntry = ex.Entries.Single();
// Using a NoTracking query means we get the entity but it is not tracked by the context
// and will not be merged with existing entities in the context.
var modifiedEntityInDatabase = await _context.BankUsers
.AsNoTracking()
.SingleAsync(d => d.ID == ((BankUser)exceptionEntry.Entity).ID);
var latestEntityInDb = _context.Entry(modifiedEntityInDatabase);
// get the latest Balance amount of the Account from Database
var latestBalance = (Decimal)latestEntityInDb.Property("Balance").CurrentValue;
if (latestBalance != accountToUpdate.Balance)
{
updateStateModel.ErrorList.Add("User.Balance", $"Current value: {latestBalance:c}");
}
// re-update the Timestamp value into User.Timestamp. The deposit process can work for the next Submit
updateStateModel.EntityTimestamp = (byte[])latestEntityInDb.Property("Timestamp").CurrentValue;
}
return(updateStateModel);
}
public async Task <IActionResult> Deposite(AccountViewModel viewModel)
{
BankUserUpdateModel result = await _userService.Deposit(viewModel.User.ID, viewModel.DepositeAmount, viewModel.User.Timestamp);
if (result.ErrorList.Any())
{
foreach (var error in result.ErrorList)
{
ModelState.AddModelError(error.Key, error.Value);
}
viewModel.User.Timestamp = null;
viewModel.User.Timestamp = result.EntityTimestamp;
// remove from ModelState to force User.Timestamp to take new value
ModelState.Remove("User.Timestamp");
}
else
{
return(RedirectToAction("Index"));
}
return(View(viewModel));
}
public async Task <IActionResult> Transfer(TransferViewModel viewModel)
{
BankUserUpdateModel result = await _userService.Transfer(
viewModel.FromUser.ID,
viewModel.ToUser.ID,
viewModel.TranferAmount,
viewModel.FromUser.Timestamp,
viewModel.ToUser.Timestamp);
if (result.ErrorList.Any())
{
foreach (var error in result.ErrorList)
{
ModelState.AddModelError(error.Key, error.Value);
}
}
else
{
return(RedirectToAction("Index"));
}
return(View(viewModel));
}
public async Task <BankUserUpdateModel> Transfer(
int fromUserId,
int toUserId,
decimal amount,
byte[] fromAccountTimestamp,
byte[] toAccountTimestamp)
{
var updateStateModel = new BankUserUpdateModel();
if (amount <= 0)
{
updateStateModel.ErrorList.Add("TranferAmount", "The amount must be larger than 0.");
updateStateModel.ErrorList.Add(string.Empty, "Unable to save changes.");
return(updateStateModel);
}
var accountToTransfer = await this.GetAccountById(fromUserId);
if (accountToTransfer == null)
{
updateStateModel.ErrorList.Add(string.Empty, "Unable to save changes. The transfer account was deleted by another user.");
return(updateStateModel);
}
if (accountToTransfer.Balance - amount < 0)
{
updateStateModel.ErrorList.Add("TranferAmount", "The withdraw amount must be larger or equals the balance amount.");
updateStateModel.ErrorList.Add(string.Empty, "Unable to save changes.");
return(updateStateModel);
}
var accountToReceive = await this.GetAccountById(toUserId);
if (accountToReceive == null)
{
updateStateModel.ErrorList.Add(string.Empty, "Unable to save changes. The received account was deleted by another user.");
return(updateStateModel);
}
try
{
using (var transaction = _context.Database.BeginTransaction())
{
// create TransferHistory record
var transferHistoryRecord = new TransferHistory
{
FromUserID = accountToTransfer.ID,
ToUserID = accountToReceive.ID,
CreatedDate = DateTime.Now,
Amount = amount
};
_context.TranferHistories.Add(transferHistoryRecord);
// transfer the amount into Account
accountToTransfer.Balance = accountToTransfer.Balance - amount;
accountToReceive.Balance = accountToReceive.Balance + amount;
// set the Timestamp value for the retrieved Account. This Timestamp value will be compared to detech concurrence issue
_context.Entry(accountToTransfer).Property("Timestamp").OriginalValue = fromAccountTimestamp;
_context.Entry(accountToReceive).Property("Timestamp").OriginalValue = toAccountTimestamp;
await _context.SaveChangesAsync();
transaction.Commit();
}
}
catch (DbUpdateConcurrencyException ex)
{
updateStateModel.ErrorList.Add(string.Empty, "The transfer is failed.");
foreach (var exceptionEntry in ex.Entries)
{
var userId = ((BankUser)exceptionEntry.Entity).ID;
// Using a NoTracking query means we get the entity but it is not tracked by the context
// and will not be merged with existing entities in the context.
var modifiedEntityInDatabase = await _context.BankUsers
.AsNoTracking()
.SingleAsync(d => d.ID == userId);
var latestEntityInDb = _context.Entry(modifiedEntityInDatabase);
// get the latest Balance amount of the Account from Database
var latestBalance = (Decimal)latestEntityInDb.Property("Balance").CurrentValue;
if (userId == accountToTransfer.ID && latestBalance != accountToTransfer.Balance)
{
updateStateModel.ErrorList.Add("FromUser.Balance", $"Current value: {latestBalance:c}");
}
if (userId == accountToReceive.ID && latestBalance != accountToReceive.Balance)
{
updateStateModel.ErrorList.Add("ToUser.Balance", $"Current value: {latestBalance:c}");
}
}
}
return(updateStateModel);
}
