先上一段最近项目中的代码，此代码可以放到自己项目中的dbContext中
public override Task<int> SaveChangesAsync()
{
List<AuditLog> AuditLogs = new List<AuditLog>();
List<DataLensTrackingLog> trackinglogs = new List<DataLensTrackingLog>();
var changeTracker = ChangeTracker.Entries().Where(p => p.State == EntityState.Added || p.State == EntityState.Deleted || p.State == EntityState.Modified);
try
{
foreach (var entity in changeTracker)
{
AuditLogs.Clear();
XmlDocument doc = new XmlDocument();
doc.AppendChild(doc.CreateElement(TrackingLog.Records));
if (entity.Entity != null)
{
var entityName = ObjectContext.GetObjectType(entity.Entity.GetType()).Name;
//string entityName = entity.Entity.GetType().Name;
EntityState state = entity.State;
switch (entity.State)
{
case EntityState.Modified:
//entityName = ObjectContext.GetObjectType(entity.Entity.GetType()).Name;
foreach (string prop in entity.OriginalValues.PropertyNames)
{
object currentValue = entity.CurrentValues[prop];
object originalValue = entity.GetDatabaseValues()[prop];//OriginalValues[prop];
if (!Object.Equals(currentValue, originalValue)&&entity.Property(prop).IsModified==true
&&prop.ToLower()!="lastupdateby")
{
AuditLogs.Add(new AuditLog
{
EntityName = entityName,
RecordID = PrimaryKeyValue(entity),
State = state,
ColumnName = prop,
OriginalValue = Convert.ToString(originalValue),
NewValue = Convert.ToString(currentValue),
});
}
}
if (AuditLogs.Count > 0)
{
TrackingLog.GetXmlForUpdate(doc, AuditLogs);
trackinglogs.Add(new DataLensTrackingLog
{
EntityName = entityName,
Email = this.Email,
XmlDoc = CompressionHelper.Compresse("XmlDoc", new UTF8Encoding().GetBytes(doc.OuterXml)),
CreateTime = DateTime.Now
});
}
break;
case EntityState.Added:
//entityName = ObjectContext.GetObjectType(entity.Entity.GetType()).Name;
foreach (string prop in entity.CurrentValues.PropertyNames)
{
AuditLogs.Add(new AuditLog
{
EntityName = entityName,
RecordID = PrimaryKeyValue(entity),
State = state,
ColumnName = prop,
OriginalValue = string.Empty,
NewValue = entity.CurrentValues[prop],
});
}
TrackingLog.GetXmlForUpdate(doc, AuditLogs);
trackinglogs.Add(new DataLensTrackingLog
{
EntityName = entityName,
Email = this.Email,
XmlDoc = CompressionHelper.Compresse("XmlDoc", new UTF8Encoding().GetBytes(doc.OuterXml)),
CreateTime = DateTime.Now
});
break;
case EntityState.Deleted:
//entityName = ObjectContext.GetObjectType(entity.Entity.GetType()).Name;
foreach (string prop in entity.OriginalValues.PropertyNames)
{
AuditLogs.Add(new AuditLog
{
EntityName = entityName,
RecordID = PrimaryKeyValue(entity),
State = state,
ColumnName = prop,
OriginalValue = entity.OriginalValues[prop],
NewValue = string.Empty,
});
}
TrackingLog.GetXmlForUpdate(doc, AuditLogs);
trackinglogs.Add(new DataLensTrackingLog
{
EntityName = entityName,
Email = this.Email,
XmlDoc = CompressionHelper.Compresse("XmlDoc", new UTF8Encoding().GetBytes(doc.OuterXml)),
CreateTime = DateTime.Now
});
break;
default:
break;
}
}
}
DataTable dt=TypeConvert.ToDataTable(trackinglogs);
SqlDataHelper.SqlBulkCopy(dt, "DataLensTrackingLog", DataBaseType.ConnLogDataStr);
return base.SaveChangesAsync();
}
catch (Exception ex)
{
throw ex;
}
}
EF6中可以覆写SaveChangesAsync(异步)或者SaveChanges来实现记录变化的跟踪，这其中包括新增、修改、和删除，
dbContext中的属性ChangeTracker可以跟踪属性的变化,即查找实体修改记录：ChangeTracker.Entries().Where(p => p.State ==EntityState.Modified);
查找新增的实体记录行：ChangeTracker.Entries().Where(p => p.State == EntityState.Added);查找删除的实体记录行：
ChangeTracker.Entries().Where(p => p.State == EntityState.Deleted)
获取实体的名字是ObjectContext.GetObjectType(entity.Entity.GetType()).Name，之前获取实体是通过以下方式：
entity.Entity.GetType().Name，但是这种方式会有一个问题，假如说存在以下实体
public partial class DataLensDataPointUniverse
{
[Key]
public int DataPointUniverseId { get; set; }
public int DomicileId { get; set; }
public int ShareClassUniverseId { get; set; }
public int DataPointId { get; set; }
public int CollectionStatusId { get; set; }
public Nullable<System.DateTime> CollectionStartDate { get; set; }
public Nullable<System.DateTime> CollectionEndDate { get; set; }
public int CollectionFrequencyId { get; set; }
public int CollectionPriorityId { get; set; }
public string Restrictions { get; set; }
public int FundFormId { get; set; }
public string InterpretationRules { get; set; }
public string Comments { get; set; }
public string QualityMeasureCompleteness { get; set; }
public string QualityMeasureTimeliness { get; set; }
public string QualityMeasureAccuracy { get; set; }
public int FundCollectionRequirementId { get; set; }
public int LEANProjectId { get; set; }
public Nullable<System.Guid> CreateBy { get; set; }
public Nullable<System.Guid> LastUpdateBy { get; set; }
public Nullable<System.DateTime> CreateDate { get; set; }
public Nullable<System.DateTime> LastUpdateDate { get; set; }
public virtual DataLensDataPoint DataLensDataPoint { get; set; }
}
这时候获取的实体名字就可能是类似于这种格式343434343_DataLensDataPoint_3434,为什么会存在这种格式呢，因为
该实体中的DataPointId是另个属性 public virtual DataLensDataPoint DataLensDataPoint { get; set; }中的外键，即
（即实体DataLensDataPoint中DataPointId）
获取属性当前值entity.CurrentValues[prop](即还未保存到数据库)，获取数据库当前值entity.GetDatabaseValues()[prop]
其中的entity.Property(prop).IsModified==true属性是来判断确实该值要存到数据库中，才要去记录日志，因为在Save
之前可能有些实体属性被标记为不做更改entity.Property(prop).IsModified==false;
获取实体主键的值可以用以下方法
private string PrimaryKeyValue(DbEntityEntry entry)
{
var objectStateEntry = ((IObjectContextAdapter)this).ObjectContext.ObjectStateManager.GetObjectStateEntry(entry.Entity);
if (null == objectStateEntry.EntityKey.EntityKeyValues)
{
return string.Empty;
}
return string.Join(",", objectStateEntry.EntityKey.EntityKeyValues.Select(item => item.Value.ToString()).ToArray());
}