This probably falls into the bonehead category, but this might bite somebody else so I'm writing it up: LINQ to SQL works best when your database tables have version fields that can be used to see change state. So recluctantly I resigned myself to give in to this and decided I'd use a consistent fieldname that wouldn't interfere with normal naming.
Version and TimeStamp may be very clear names, but they are also likely fieldnames that can be chosen for real field data in a table. So I decided to use:
_version
Nice and simple and clear and not likely for field name interference.
But LINQ to SQL gets confused in some situations by fields with a leading underscore. The code generated looks Ok from what I can see:
[Column(Name="[_version]", Storage="__version", AutoSync=AutoSync.Always, DbType="rowversion", IsDbGenerated=true, IsVersion=true, UpdateCheck=UpdateCheck.Never)]
[DataMember(Order=28)]
public byte[] _version
{ get
{ return this.@__version;
}
set
{ if ((this.@__version != value))
{ this.On_versionChanging(value);
this.SendPropertyChanging();
this.@__version = value;
this.SendPropertyChanged("_version"); this.On_versionChanged();
}
}
}
but @__version/_version returns null in dynamic query scenarios. For example in the following code the second query fails to load the timestamp field:
// *** this works
TimeTrakkerContext ctx = new TimeTrakkerContext();
tt_customer cust33 = ctx.tt_customers.Single(c => c.Pk == 1);
Response.Write( cust33._version);
// *** this doesn't
TimeTrakkerContext ctx2 = new TimeTrakkerContext();
tt_customer cust32 = ctx2.ExecuteQuery<tt_customer>("select * from tt_customers where pk = 1").Single();Response.Write( cust32._version);
If I go in and change the _version field to tversion in the database and adjust the field names accordingly in the code:
// *** this works
TimeTrakkerContext ctx = new TimeTrakkerContext();
tt_customer cust33 = ctx.tt_customers.Single(c => c.Pk == 1);
Response.Write( cust33.tversion);
// *** now it works
TimeTrakkerContext ctx2 = new TimeTrakkerContext();
tt_customer cust32 = ctx2.ExecuteQuery<tt_customer>("select * from tt_customers where pk = 1").Single();Response.Write( cust32.tversion);
then it all works as expected.
For now better safe than sorry - I'm not using any leading underscores in fields and especially not timestamp fields. <g>
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