/// <summary>
/// Ensures the automatic history rollback.
/// The entity goes back to a defined previous state or its last previous state.
/// </summary>
/// <param name="context">The context.</param>
/// <param name="entity">The entity being restaured to its previous state.</param>
/// <param name="historyNumber">[Optional] The history number from where rollback is done.</param>
public static void AutoHistoryRollback <T>(this DbContext context, ref T entity, int?historyNumber = null) where T : class
{
if (String.IsNullOrEmpty(context.Entry(entity).PrimaryKey()))
{
throw new ArgumentNullException(String.Format("The entity {0} doesn't have a valid primary key, so can not be rollbacked", entity.GetType().Name));
}
if (context.Entry(entity).State == EntityState.Added)
{
throw new Exception(String.Format("The entity {0} is added, it can not be rollbacked", entity.GetType().Name));
}
context.Entry(entity).State = EntityState.Detached;
string keyString = context.Entry(entity).PrimaryKey();
var historicChanges = context.Set <AutoHistory>().Where(h => h.RowId == keyString);
AutoHistory history = null;
if (historicChanges.Count() == 1)
{
return;
}
if (historyNumber != null)
{
history = historicChanges.Where(h => h.Id == historyNumber).FirstOrDefault();
}
else
{
history = historicChanges.OrderByDescending(h => h.Id).FirstOrDefault();
}
if (history != null)
{
try
{
// If this entity type does not exist in its assembly, GetType throws a TypeLoadException.
//Type elementType = Type.GetType(history.EntityName, true);
JObject jsonObj = JObject.Parse(history.Changed);
entity = Newtonsoft.Json.JsonConvert.DeserializeObject <T>(jsonObj.GetValue("before").ToString());
context.Remove(history);
context.Entry(entity).State = EntityState.Modified;
}
catch (Newtonsoft.Json.JsonReaderException ex)
{
Console.WriteLine("{0}: Unable to load json string", ex.Message);
}
catch (TypeLoadException e)
{
Console.WriteLine("{0}: Unable to load type", e.GetType().Name);
}
}
}
private static void WriteHistoryDeletedState(AutoHistory history, EntityEntry entry, IEnumerable <PropertyEntry> properties)
{
dynamic json = new System.Dynamic.ExpandoObject();
foreach (var prop in properties)
{
((IDictionary <String, Object>)json)[prop.Metadata.Name] = prop.OriginalValue;
}
history.RowId = entry.PrimaryKey();
history.Kind = EntityState.Deleted;
history.Changed = JsonSerializer.Serialize(json, AutoHistoryOptions.Instance.JsonSerializerOptions);
}
/// <summary>
/// Ensures the automatic history.
/// </summary>
/// <param name="context">The context.</param>
public static void EnsureAutoHistory(this DbContext context)
{
// TODO: only record the changed properties.
var jsonSetting = new JsonSerializerSettings
{
ContractResolver = new EntityContractResolver(context),
};
var entries = context.ChangeTracker.Entries().Where(e => e.State != EntityState.Unchanged &&
e.State != EntityState.Detached &&
IncludeEntity(e)).ToList();
if (entries.Count == 0)
{
return;
}
foreach (var entry in entries)
{
var history = new AutoHistory
{
TypeName = entry.Entity.GetType().FullName,
};
switch (entry.State)
{
case EntityState.Added:
// REVIEW: what's the best way to do this?
history.SourceId = "0";
history.Kind = EntityState.Added;
history.AfterJson = JsonConvert.SerializeObject(entry.Entity, Formatting.Indented, jsonSetting);
break;
case EntityState.Deleted:
history.SourceId = entry.PrimaryKey();
history.Kind = EntityState.Deleted;
history.BeforeJson = JsonConvert.SerializeObject(entry.Entity, Formatting.Indented, jsonSetting);
break;
case EntityState.Modified:
history.SourceId = entry.PrimaryKey();
history.Kind = EntityState.Modified;
history.BeforeJson = JsonConvert.SerializeObject(entry.Original(), Formatting.Indented, jsonSetting);
history.AfterJson = JsonConvert.SerializeObject(entry.Entity, Formatting.Indented, jsonSetting);
break;
default:
continue;
}
context.Add(history);
}
}
private static void WriteHistoryAddedState(AutoHistory history, IEnumerable <PropertyEntry> properties)
{
dynamic json = new System.Dynamic.ExpandoObject();
foreach (var prop in properties)
{
if (prop.Metadata.IsKey() || prop.Metadata.IsForeignKey())
{
continue;
}
((IDictionary <String, Object>)json)[prop.Metadata.Name] = prop.CurrentValue;
}
// REVIEW: what's the best way to set the RowId?
history.RowId = "0";
history.Kind = EntityState.Added;
history.Changed = JsonSerializer.Serialize(json);
}
private static void WriteHistoryModifiedState(AutoHistory history, EntityEntry entry, IEnumerable <PropertyEntry> properties)
{
dynamic json = new System.Dynamic.ExpandoObject();
dynamic bef = new System.Dynamic.ExpandoObject();
dynamic aft = new System.Dynamic.ExpandoObject();
PropertyValues databaseValues = null;
foreach (var prop in properties)
{
if (prop.IsModified)
{
if (prop.OriginalValue != null)
{
if (!prop.OriginalValue.Equals(prop.CurrentValue))
{
((IDictionary <String, Object>)bef)[prop.Metadata.Name] = prop.OriginalValue;
}
else
{
databaseValues ??= entry.GetDatabaseValues();
var originalValue = databaseValues.GetValue <object>(prop.Metadata.Name);
((IDictionary <String, Object>)bef)[prop.Metadata.Name] = originalValue;
}
}
else
{
((IDictionary <String, Object>)bef)[prop.Metadata.Name] = null;
}
((IDictionary <String, Object>)aft)[prop.Metadata.Name] = prop.CurrentValue;
}
}
((IDictionary <String, Object>)json)["before"] = bef;
((IDictionary <String, Object>)json)["after"] = aft;
history.RowId = entry.PrimaryKey();
history.Kind = EntityState.Modified;
history.Changed = JsonSerializer.Serialize(json, AutoHistoryOptions.Instance.JsonSerializerOptions);
}
internal static AutoHistory AutoHistory(this EntityEntry entry)
{
var history = new AutoHistory {
TableName = entry.Metadata.Relational().TableName,
};
// Get the mapped properties for the entity type.
// (include shadow properties, not include navigations & references)
var properties = entry.Properties;
var json = new JObject();
switch (entry.State)
{
case EntityState.Added:
foreach (var prop in properties)
{
if (prop.Metadata.IsKey() || prop.Metadata.IsForeignKey())
{
continue;
}
//json[prop.Metadata.Name] = new JObject(prop.CurrentValue);
json[prop.Metadata.Name] = JToken.FromObject(prop.CurrentValue);
}
// REVIEW: what's the best way to set the RowId?
history.RowId = "0";
history.Kind = EntityState.Added;
history.Changed = json.ToString();
break;
case EntityState.Modified:
var bef = new JObject();
var aft = new JObject();
foreach (var prop in properties)
{
if (prop.IsModified)
{
bef[prop.Metadata.Name] = JToken.FromObject(prop.OriginalValue);
aft[prop.Metadata.Name] = JToken.FromObject(prop.CurrentValue);
}
}
json["Before"] = bef;
json["After"] = aft;
history.RowId = entry.PrimaryKey();
history.Kind = EntityState.Modified;
history.Changed = json.ToString();
break;
case EntityState.Deleted:
foreach (var prop in properties)
{
json[prop.Metadata.Name] = JToken.FromObject(prop.OriginalValue);
}
history.RowId = entry.PrimaryKey();
history.Kind = EntityState.Deleted;
history.Changed = json.ToString();
break;
case EntityState.Detached:
case EntityState.Unchanged:
default:
throw new NotSupportedException("AutoHistory only support Deleted and Modified entity.");
}
return(history);
}
