private static void Method08()
{
Member member = new Member {
Id = 1, Password = "******" + DateTime.Now.Second
};
using (var db = new DataContext())
{
//先查询一次，让上下文中存在相同主键的对象
Member oldMember = db.Members.Single(m => m.Id == 1);
Console.WriteLine("更新前：{0}。", oldMember.AddDate);
try
{
DbEntityEntry <Member> entry = db.Entry(member);
entry.State = EntityState.Unchanged;
entry.Property("Password").IsModified = true;
}
catch (InvalidOperationException)
{
ObjectContext objectContext = ((IObjectContextAdapter)db).ObjectContext;
ObjectStateEntry objectEntry = objectContext.ObjectStateManager.GetObjectStateEntry(oldMember);
objectEntry.ApplyCurrentValues(member);
objectEntry.ChangeState(EntityState.Unchanged);
objectEntry.SetModifiedProperty("Password");
}
db.Configuration.ValidateOnSaveEnabled = false;
int count = db.SaveChanges();
db.Configuration.ValidateOnSaveEnabled = true;
Console.WriteLine("操作结果：{0}", count > 0 ? "更新成功。" : "未更新。");
Member newMember = db.Members.Single(m => m.Id == 1);
Console.WriteLine("更新后：{0}。", newMember.Password);
}
}
//场景三的异常处理，从ObjectContext着手处理
public void Method8()
{
const string userName = "******";
long id;
using (var db = new DefaultDbContext())
{
id = db.Set <SysUser>().Single(m => m.UserName == userName).Id;
}
SysUser user = new SysUser {
Id = id, Password = "******" + DateTime.Now.Second
};
using (var db = new DefaultDbContext())
{
//关闭自动跟踪，方便调试查看
db.Configuration.AutoDetectChangesEnabled = false;
//通过查询，让上下文中存在相同主键的对象
SysUser oldUser = db.Set <SysUser>().Find(user.Id);
System.Console.WriteLine("更新前：{0}。", oldUser.Password);
try
{
DbEntityEntry <SysUser> entry = db.Entry(user);
entry.State = EntityState.Unchanged;
entry.Property("Password").IsModified = true;
}
catch (InvalidOperationException)
{
ObjectContext objectContext = ((IObjectContextAdapter)db).ObjectContext;
ObjectStateEntry objectEntry = objectContext.ObjectStateManager.GetObjectStateEntry(oldUser);
objectEntry.ApplyCurrentValues(user);
objectEntry.ChangeState(EntityState.Unchanged);
objectEntry.SetModifiedProperty("Password");
}
db.Configuration.ValidateOnSaveEnabled = false;
int count = db.SaveChanges();
db.Configuration.ValidateOnSaveEnabled = true;
System.Console.WriteLine("操作结果：{0}", count > 0 ? "更新成功。" : "未更新。");
SysUser newUser = db.Set <SysUser>().Single(m => m.Id == id);
System.Console.WriteLine("更新后：{0}。", newUser.Password);
}
}
public static void Update <TEntity, TKey>(this DbContext dbContext,
Expression <Func <TEntity, object> > propertyExpression, params TEntity[] entities)
where TEntity : EntityBase <TKey>
{
if (propertyExpression == null)
{
throw new ArgumentNullException("propertyExpression");
}
if (entities == null)
{
throw new ArgumentNullException("entities");
}
ReadOnlyCollection <MemberInfo> memberInfos = ((dynamic)propertyExpression.Body).Members;
foreach (TEntity entity in entities)
{
DbSet <TEntity> dbSet = dbContext.Set <TEntity>();
try
{
DbEntityEntry <TEntity> entry = dbContext.Entry(entity);
//entry.State = EntityState.Unchanged;
foreach (MemberInfo memberInfo in memberInfos)
{
entry.Property(memberInfo.Name).IsModified = true;
}
}
catch (InvalidOperationException)
{
TEntity originalEntity = dbSet.Local.Single(m => Equals(m.SysNo, entity.SysNo));
ObjectContext objectContext = ((IObjectContextAdapter)dbContext).ObjectContext;
ObjectStateEntry objectEntry = objectContext.ObjectStateManager.GetObjectStateEntry(originalEntity);
objectEntry.ApplyCurrentValues(entity);
objectEntry.ChangeState(EntityState.Unchanged);
foreach (MemberInfo memberInfo in memberInfos)
{
objectEntry.SetModifiedProperty(memberInfo.Name);
}
}
}
}