simple functions with single datasources lose their datasource when the chart is written using TStream.WriteObjectResource and later reloading it.

This is because of the 'Datasources' defineproiperties implementation and the IsDataSourceStored implementation.

When only 1 datasource is present, it is stored using a component link instead of a component name (like de datasources list). 

When the chart is reloaded later on, the series get to be owned by the chart rather than the form containg the chart causing the single datsource link not be resolved.

I have created a solution and verified that it works in my case. It is not likely to break any existing code, so here it is. IMHO it could be even fixed a bit better if the .Loaded routine that resolves the FTempDatasourcesList would be a bit more intelligent.

To me the issue is critical since it blocks storing and restoring charts defined /adjusted by my users.


Here are my patches for teengine.pas:

procedure TChartSeries.DefineProperties(Filer: TFiler);
begin
  inherited;

  Filer.DefineProperty('DataSources',ReadDataSources,WriteDataSources,
       Assigned(FDataSources)
       {$ifdef HH_PATCH_TC_DATASOURCEPERSISTANCE}
         and (FDataSources.Count>0) and not IsDataSourceStored
       {$else}
         and (FDataSources.Count>1)
       {$endif}
       );  { <-- don't translate }

  Filer.DefineProperty('CustomHorizAxis', ReadCustomHorizAxis,
                                          WriteCustomHorizAxis,Assigned(FCustomHorizAxis));  { <-- don't translate }
  Filer.DefineProperty('CustomVertAxis', ReadCustomVertAxis,
                                          WriteCustomVertAxis,Assigned(FCustomVertAxis));  { <-- don't translate }

  Filer.DefineBinaryProperty('Data',ReadData,WriteData,IsDataStored);
end;


Function TChartSeries.IsDataSourceStored:Boolean;
Begin
{$ifdef HH_PATCH_TC_DATASOURCEPERSISTANCE}
  // chart custom elements always through Datasources property (linked by component name)
  result:=(DataSources.Count=1) and not (Datasources[0] is TCustomChartElement);
{$else}
  result:=DataSources.Count=1;;
{$endif}
end;