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我使用实体框架4.1，我有我的DbContext覆盖SaveChanges审计属性更改。代码从'GetEntryValueInString'返回空值。它的因果“如果（entry.Entity是EntityObject）”这种情况在所有情况下都失败了。如果我评论条件我有另一个问题像CurrentValues和OriginalValues变得相同。DbDataRecord - entry.CurrentValues和entry.originalValues是相同的
namespace mymodel
{
using System;
using System.Collections.Generic;
using System.Data;
using System.Data.Entity;
using System.Data.Entity.Infrastructure;
using System.Data.Objects;
using System.Data.Objects.DataClasses;
using System.IO;
using System.Reflection;
using System.Runtime.Serialization;
using System.Xml;
using System.Xml.Linq;
using System.Xml.Serialization;
public partial class DbEntities : DbContext
{
public DbEntities()
: base("name=DbEntities ")
{
}
protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
throw new UnintentionalCodeFirstException();
}
public DbSet<DBAudit> DBAudits { get; set; }
public string UserName { get; set; }
List<DBAudit> auditTrailList = new List<DBAudit>();
public enum AuditActions
{
I,
U,
D
}
public override int SaveChanges()
{
ChangeTracker.DetectChanges(); // Important!
ObjectContext ctx = ((IObjectContextAdapter)this).ObjectContext;
IEnumerable<ObjectStateEntry> changes = ctx.ObjectStateManager.GetObjectStateEntries(EntityState.Added | EntityState.Deleted | EntityState.Modified);
foreach (ObjectStateEntry stateEntryEntity in changes)
{
if (!stateEntryEntity.IsRelationship &&
stateEntryEntity.Entity != null &&
!(stateEntryEntity.Entity is DBAudit))
{//is a normal entry, not a relationship
DBAudit audit = this.AuditTrailFactory(stateEntryEntity, UserName);
auditTrailList.Add(audit);
}
}
if (auditTrailList.Count > 0)
{
foreach (var audit in auditTrailList)
{//add all audits
//this.AddToDBAudit(audit);
}
}
return base.SaveChanges();
}
private DBAudit AuditTrailFactory(ObjectStateEntry entry, string UserName)
{
DBAudit audit = new DBAudit();
audit.UpdateDate = DateTime.Now;
audit.TableName = entry.EntitySet.Name;
audit.UserId = UserName;
if (entry.State == EntityState.Added)
{//entry is Added
audit.NewData = GetEntryValueInString(entry, false);
audit.Actions = AuditActions.I.ToString();
}
else if (entry.State == EntityState.Deleted)
{//entry in deleted
audit.OldData = GetEntryValueInString(entry, true);
audit.Actions = AuditActions.D.ToString();
}
else
{//entry is modified
audit.OldData = GetEntryValueInString(entry, true);
audit.NewData = GetEntryValueInString(entry, false);
audit.Actions = AuditActions.U.ToString();
IEnumerable<string> modifiedProperties = entry.GetModifiedProperties();
//assing collection of mismatched Columns name as serialized string
//audit.TableName = XMLSerializationHelper.XmlSerialize(modifiedProperties.ToArray());
}
return audit;
}
private string GetEntryValueInString(ObjectStateEntry entry, bool isOrginal)
{
if (entry.Entity is EntityObject)
{
object target = CloneEntity((EntityObject)entry.Entity);
foreach (string propName in entry.GetModifiedProperties())
{
object setterValue = null;
if (isOrginal)
{
//Get orginal value
setterValue = entry.OriginalValues[propName];
}
else
{
//Get orginal value
setterValue = entry.CurrentValues[propName];
}
//Find property to update
PropertyInfo propInfo = target.GetType().GetProperty(propName);
//update property with orgibal value
if (setterValue == DBNull.Value)
{//
setterValue = null;
}
propInfo.SetValue(target, setterValue, null);
}//end foreach
XmlSerializer formatter = new XmlSerializer(target.GetType());
XDocument document = new XDocument();
using (XmlWriter xmlWriter = document.CreateWriter())
{
formatter.Serialize(xmlWriter, target);
}
return document.Root.ToString();
}
return null;
}
public EntityObject CloneEntity(EntityObject obj)
{
DataContractSerializer dcSer = new DataContractSerializer(obj.GetType());
MemoryStream memoryStream = new MemoryStream();
dcSer.WriteObject(memoryStream, obj);
memoryStream.Position = 0;
EntityObject newObject = (EntityObject)dcSer.ReadObject(memoryStream);
return newObject;
}
public DbSet<Area> Areas { get; set; }
public DbSet<Country> Countries { get; set; }
public DbSet<Event> Events { get; set; }
public DbSet<Group> Groups { get; set; }
public DbSet<Holiday> Holidays { get; set; }
public DbSet<Location> Locations { get; set; }
public DbSet<Notification> Notifications { get; set; }
public DbSet<Receipt> Receipts { get; set; }
public DbSet<Report> Reports { get; set; }
public DbSet<Role> Roles { get; set; }
public DbSet<State> States { get; set; }
public DbSet<Store> Stores { get; set; }
public DbSet<TimeZone> TimeZones { get; set; }
}
}