IDictionarys Are Very Valuable



  • I found this bit of joy when I went to override a method in ASP.NET:

    protected override int ExecuteUpdate(IDictionary keys, IDictionary values, IDictionary oldValues)

    Call me behind the times, but I would have thought... uh... That the keys and values were both held in a dictionary...

    Oh well. I suppose this means something sensible, but I'll be damned if I know what it is at first glance.
     



  • Not much of a WTF.

    Keys is just a dictionary for filtering (when not databound - otherwise meaning changes). That means you can change values where keys [a=1; b=2] - multicolumn WHERE clause.
    Values updates columns with names from values.Keys with values from values.Values.

    Though I still have no idea what oldValues does... It's not documented and I don't really see what would happen when more than one row is updated...

    Example from MSDN for this method is "the real WTF":

    public override bool CanUpdate {
    get {
    return false;
    }
    }
    protected override int ExecuteUpdate(IDictionary keys, IDictionary values, IDictionary oldValues)
    {
    throw new NotSupportedException();
    }

     Yup... that surely helped :D



  • I did figure out the meaning soon after and, as you saw, MSDN was not much help. However, the MSDN example is part of a larger example which only implements Select. So, they carved it up, exceptions and all, into the individual examples...

    I'm in the middle of a project to write a "generalized" solution for managing table data with no special fields. Beware of assignments to "generalize" something, as managers will not allocate enough time to complete them, no matter what.
     


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