public static DataConflictInfo ApplyPolicy(DataConflictPolicy policy, DbUpdateConcurrencyException exception)
{
DbEntityEntry entry = exception.Entries.Single();
switch (policy)
{
case DataConflictPolicy.DatabaseWins:
// Update the values of the entity that failed to save from the store
entry.Reload();
return(null);
case DataConflictPolicy.ClientWins:
// Update original values from the database
entry.OriginalValues.SetValues(entry.GetDatabaseValues());
return(null);
case DataConflictPolicy.AskClient:
// Get the current entity values and the values in the database
var currentValues = entry.CurrentValues;
var databaseValues = entry.GetDatabaseValues().Clone();
return(new DataConflictInfo
{
CurrentValues = currentValues,
DatabaseValues = databaseValues
});
default:
return(null);
}
}
public void Validate(int expectedObjectsCount, DataConflictPolicy dataConflictPolicy)
{
if (dataConflictPolicy == DataConflictPolicy.DatabaseWins &&
(this.AlteredObjectsCount != 0 || this.AlteredIds.Count() != expectedObjectsCount))
{
throw new DalException(DalErrorType.SaveResultPersistenceValidationFailure,
"Persistence validation failure");
}
if (dataConflictPolicy == DataConflictPolicy.ClientWins &&
(this.AlteredObjectsCount != expectedObjectsCount || this.AlteredIds.Count() != expectedObjectsCount))
{
throw new DalException(DalErrorType.SaveResultPersistenceValidationFailure,
"Persistence validation failure");
}
}
protected async Task <SaveResult> SaveAsync(DataConflictPolicy policy)
{
bool saveFailed;
do
{
saveFailed = false;
try
{
int result = await this.context.SaveChangesAsync();
return(new SaveResult {
AlteredObjectsCount = result
});
}
catch (DbUpdateConcurrencyException exception)
{
if (policy == DataConflictPolicy.NoPolicy)
{
throw new DalException(DalErrorType.BaseServiceDataConflictWithNoPolicy,
"Data conflict (Optimistic concurrency)");
}
saveFailed = true;
DataConflictInfo info = OptimisticConcurrency.ApplyPolicy(policy, exception);
if (info != null)
{
throw new DataConflictException(DalErrorType.BaseServiceDataConflictWithAskClientPolicy, info);
}
}
catch (Exception exception)
{
exception.HandleException();
}
} while (saveFailed);
return(null);
}
public void SetPolicy(DataConflictPolicy policy)
{
base.policy = policy;
}
public BaseService(IDbContext context)
{
this.context = context;
this.policy = DataConflictPolicy.ClientWins;
}
