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[ASP.net教程]EF6 中tracking log使用方法总结


    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();          = new 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.Getnew DataLensTrackingLog                  {                    EntityName = entityName,                    Email = this.Email,                    = CompressionHelper.Compresse("", new UTF8Encoding().GetBytes(doc.Outer= 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.Getnew DataLensTrackingLog                {                  EntityName = entityName,                  Email = this.Email,                  = CompressionHelper.Compresse("", new UTF8Encoding().GetBytes(doc.Outer= 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.Getnew DataLensTrackingLog                {                  EntityName = entityName,                  Email = this.Email,                  = CompressionHelper.Compresse("", new UTF8Encoding().GetBytes(doc.Outer= 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());
}