Question

Why don’t the entities returned below update? They are null on the Get and remain null after the Save (in the db) even though the stocktakeid variable has values.

protected void GetPipelineState()
        {
            InventoryModelDataContext context = new InventoryModelDataContext(this.ConnectionString);
            var f = from pe in context.StockTakePipelines
                    where pe.StockTakeId == null
                    select pe;
            this.PipeLine = f;
        }

        protected void SavePipelineState()
        {
            InventoryModelDataContext context = new InventoryModelDataContext(this.ConnectionString);
            foreach (StockTakePipeline p in this.PipeLine)
            {
                p.StockTakeId = this.StockTakeId;
            }
            context.SubmitChanges();
        }

EDIT : Re PK

Answer 1

You’re changing entities from the context local to GetPipelineState(), and then calling SubmitChanges() on the context local to SavePipelineState().

Try something more like:

    protected IQueryable<StockTakePipeline> GetPipelineState(InventoryModelDataContext context)
    {
        return from pe in context.StockTakePipelines
                where pe.StockTakeId == null
                select pe;
    }

    protected void SavePipelineState()
    {
        using(InventoryModelDataContext context = new InventoryModelDataContext(this.ConnectionString));
        {
          foreach (StockTakePipeline p in GetPipelineState(context))
          {
              p.StockTakeId = this.StockTakeId;
          }
          context.SubmitChanges();
        }
    }

Edit:

Just a note for someone else finding this question. Another thing that will cause entities to not update is if they don’t implement INotifyPropertyChanging and INotifyPropertyChanged, which they normally will, but won’t if either you hand-code the class and forget to implement those, or if the table has no primary key (in which case there’s no way to do an update on a given row anyway since it can’t be identified, and the code gen drops the implementation of those now-pointless interfaces as an optimisation).