问题描述
有没有办法强制 LINQ-to-SQL 将列视为脏列?在全球范围内就足够了....
Is there a way to force LINQ-to-SQL to treat a column as dirty? Globally would suffice....
基本上,我在与 L2S 交谈的遗留系统上的一些审计代码有问题,想象一下:
Basically, I've got a problem with some audit code on a legacy system that I'm talking to with L2S, imagine:
var ctx = new SomeDataContext(); // disposed etc - keeping it simple for illustration var cust = ctx.Customers.First(); // just for illustration cust.SomeRandomProperty = 17; // whatever cust.LastUpdated = DateTime.UtcNowl; cust.UpdatedBy = currentUser; ctx.SubmitChanges(); // uses auto-generated TSQL
这很好,但如果同一用户连续更新两次,UpdatedBy 是 NOP,TSQL 将(大致):
This is fine, but if the same user updates it twice in a row, the UpdatedBy is a NOP, and the TSQL will be (roughly):
UPDATE [dbo].[Customers] SET SomeRandomColumn = @p0 , LastUpdated = @p1 -- note no UpdatedBy WHERE Id = @p2 AND Version = @p3
就我而言,问题在于当前所有表上都有一个带大括号的审计触发器,它检查审计列是否已更新,如果没有则假定开发人员有错(替换 SUSER_SNAME(),尽管它也很容易抛出错误).
In my case, the problem is that there is currently a belt-and-braces audit trigger on all tables, which checks to see if the audit column has been updated, and if not assumes the developer is at fault (substituting SUSER_SNAME(), although it could just as readily throw an error).
我真正希望能够做的是说始终更新此列,即使它不脏" - 这可能吗?
What I'd really like to be able to do is say "always update this column, even if it isn't dirty" - is this possible?
推荐答案
基于 KristoferA 的回答,我在下面得到了like;这是邪恶而脆弱的(反射通常是),但现在可能已经足够了.战斗的另一面是改变触发器的行为:
Based on KristoferA's answer, I ended up with something like below; this is evil and brittle (reflection often is), but may have to suffice for now. The other side of the battle is to change the triggers to behave:
partial class MyDataContext // or a base-class { public override void SubmitChanges(System.Data.Linq.ConflictMode failureMode) { this.MakeUpdatesDirty("UpdatedBy", "Updated_By"); base.SubmitChanges(failureMode); } } public static class DataContextExtensions { public static void MakeUpdatesDirty( this DataContext dataContext, params string[] members) { if (dataContext == null) throw new ArgumentNullException("dataContext"); if (members == null) throw new ArgumentNullException("members"); if (members.Length == 0) return; // nothing to do foreach (object instance in dataContext.GetChangeSet().Updates) { MakeDirty(dataContext, instance, members); } } public static void MakeDirty( this DataContext dataContext, object instance , params string[] members) { if (dataContext == null) throw new ArgumentNullException("dataContext"); if (instance == null) throw new ArgumentNullException("instance"); if (members == null) throw new ArgumentNullException("members"); if (members.Length == 0) return; // nothing to do const BindingFlags AllInstance = BindingFlags.Instance | BindingFlags.NonPublic | BindingFlags.Public; object commonDataServices = typeof(DataContext) .GetField("services", AllInstance) .GetValue(dataContext); object changeTracker = commonDataServices.GetType() .GetProperty("ChangeTracker", AllInstance) .GetValue(commonDataServices, null); object trackedObject = changeTracker.GetType() .GetMethod("GetTrackedObject", AllInstance) .Invoke(changeTracker, new object[] { instance }); var memberCache = trackedObject.GetType() .GetField("dirtyMemberCache", AllInstance) .GetValue(trackedObject) as BitArray; var entityType = instance.GetType(); var metaType = dataContext.Mapping.GetMetaType(entityType); for(int i = 0 ; i < members.Length ; i++) { var member = entityType.GetMember(members[i], AllInstance); if(member != null && member.Length == 1) { var metaMember = metaType.GetDataMember(member[0]); if (metaMember != null) { memberCache.Set(metaMember.Ordinal, true); } } } } }