/// <summary>
/// Reverts pending changes made to the database context.
/// </summary>
/// <param name="context">
/// The database context whose pending changes to revert.
/// </param>
/// <param name="cancellationToken">
/// A token to monitor for cancellation requests.
/// </param>
/// <returns>A task that represents the asynchronous operation.</returns>
public static async Task UndoChangesAsync(this IAuditedContext context, CancellationToken cancellationToken = default)
{
if (context.ChangeTracker.AutoDetectChangesEnabled)
{
context.ChangeTracker.DetectChanges();
}
foreach (var entry in context.ChangeTracker.Entries())
{
switch (entry.State)
{
case EntityState.Deleted:
entry.State = EntityState.Unchanged;
break;
case EntityState.Modified:
await entry.ReloadAsync(cancellationToken);
break;
case EntityState.Added:
entry.State = EntityState.Detached;
break;
}
}
}
public static async Task <int> ConcurrencySave(this IAuditedContext context, int retryAttempts, ILogger logger, CancellationToken cancellationToken)
{
var validationErrors = context.GetValidationErrors();
if (validationErrors.Any())
{
throw new ValidationException($"Validation errors:\n {string.Join(Environment.NewLine, validationErrors)}");
}
context.SetAuditingFields();
bool successfulSave;
var currentAttempt = 1;
do
{
try
{
return(await context.SaveChangesAsync(cancellationToken));
}
catch (DbUpdateConcurrencyException exception) when(currentAttempt <= retryAttempts)
{
logger.LogWarning(exception, $"Attempt {currentAttempt}/{retryAttempts} failed. Retrying...");
successfulSave = false;
currentAttempt++;
}
} while (!successfulSave);
throw new InvalidOperationException("A serious issue has been encountered! Contact support immediately.");
}
/// <summary>
/// Discards the prepared audit records. This method should be called
/// when the actual changes could not be saved to the database.
/// </summary>
/// <param name="context">
/// The database context whose changes were recorded.
/// </param>
/// <param name="cancellationToken">
/// A token to monitor for cancellation requests.
/// </param>
/// <returns>A task that represents the asynchronous operation.</returns>
public static async Task DiscardRecordedChangesAsync(this IAuditedContext context, CancellationToken cancellationToken = default)
{
if (!context.CanAudit())
{
return;
}
await Task.WhenAll(context.ChangeRecorders.Select(x => x.DiscardAsync(cancellationToken)));
}
/// <summary>
/// Determines whether the database context is configured to support
/// auditing.
/// </summary>
/// <param name="auditedContext">The database context.</param>
/// <returns>
/// <c>true</c> if the services required for auditing are set; otherwise,
/// <c>false</c>.
/// </returns>
public static bool CanAudit(this IAuditedContext auditedContext)
{
if (auditedContext == null)
{
throw new ArgumentNullException(nameof(auditedContext));
}
return(auditedContext.ChangeRecorders?.Any() == true &&
auditedContext.Identity != null);
}
public static void SetAuditingFields(this IAuditedContext context)
{
if (context.ContextScope == null)
{
throw new InvalidOperationException($"{nameof(context.ContextScope)} has not bet set. Cannot set audit fields in {nameof(IAuditedContext)}");
}
foreach (var stateAction in context.ContextScope.StateActions)
{
InvokeStateActionPerEntity(context.ChangeTracker.Entries().Where(entry => entry.State == stateAction.Key).ToList(), stateAction.Value);
}
}
private static void RecordChange(this IAuditedContext context, EntityEntry entity, IAuditedEntity auditedEntity)
{
if (!context.CanAudit())
{
return;
}
switch (entity.State)
{
case EntityState.Added:
foreach (var changeRecorder in context.ChangeRecorders)
{
changeRecorder.RecordAdd(auditedEntity);
}
break;
case EntityState.Deleted:
foreach (var changeRecorder in context.ChangeRecorders)
{
changeRecorder.RecordDelete(auditedEntity);
}
break;
case EntityState.Modified:
foreach (var property in entity.CurrentValues.Properties)
{
var entry = entity.Property(property.Name);
// Note: do not change the line below into `!=`!
// `Equals(object, object)` calls an overridden Equals,
// whereas `object != object` does not.
if (entry.IsModified && !Equals(entry.CurrentValue, entry.OriginalValue))
{
foreach (var changeRecorder in context.ChangeRecorders)
{
changeRecorder.RecordChange(auditedEntity, property.Name, entry.OriginalValue, entry.CurrentValue);
}
}
}
break;
}
}
/// <summary>
/// Records the currently tracked changes in the database context to all
/// change recorders.
/// </summary>
/// <param name="context">
/// The database context that contains the changes.
/// </param>
public static void RecordChanges(this IAuditedContext context)
{
if (context.ChangeTracker.AutoDetectChangesEnabled)
{
context.ChangeTracker.DetectChanges();
}
foreach (var entity in context.ChangeTracker.Entries().Where(e => e.Entity is IAuditedEntity))
{
var auditedEntity = (IAuditedEntity)entity.Entity;
switch (entity.State)
{
case EntityState.Added:
auditedEntity.Created = DateTimeOffset.Now;
auditedEntity.CreatedBy = context.Identity?.Id;
break;
case EntityState.Modified:
auditedEntity.LastModified = DateTimeOffset.Now;
auditedEntity.LastModifiedBy = context.Identity?.Id;
break;
}
context.RecordChange(entity, auditedEntity);
}
if (context.CanAudit())
{
foreach (var changeRecorder in context.ChangeRecorders)
{
if (changeRecorder is IHasParentContext parentContextRecorder)
{
parentContextRecorder.ParentContext = (IAuditContext)context;
}
changeRecorder.OnSavingChanges();
}
}
}
public static ContextRepository <IAuditedContext> Create(IAuditedContext context)
{
return(new ContextRepository <IAuditedContext>(context, new Mock <ILogger <IAuditedContext> >().Object));
}
public static IDictionary <object, ICollection <ValidationResult> > GetValidationErrors(this IAuditedContext context)
{
var validationErrors = new Dictionary <object, ICollection <ValidationResult> >();
context.ChangeTracker.Entries().Where(entry => _entityStates.Contains(entry.State)).ToList().ForEach(entry =>
{
var ValidationResult = new List <ValidationResult>();
if (!Validator.TryValidateObject(entry.Entity, new ValidationContext(entry.Entity), ValidationResult, true))
{
validationErrors.Add(entry.Entity, ValidationResult);
}
});
return(validationErrors);
}
