OnMarketData and Drawing Tools... AttachedTo is null unless chart is refreshed

[neoikon]

I am building a Drawing Tool that requires OnMarketdata() support. I was told by Patrick H to place this in OnStateChange() when State.Active. Something similar to this:

if (AttachedTo != null)
{
marketData = new MarketData(AttachedTo.Instrument);
marketData.Update += OnMarketData;
}

The problem is, "AttachedTo" is always null when you first place the drawing object on the chart. Once you refresh the chart, it runs fine.

I believe the problem is that all the States are run/handled before the object is actually placed onto the chart. Thus, AttachedTo is null, thus it never adds the event handler. When you refresh the chart, it's already attached, so it works fine.

Is there a better place to add the event handler other than OnStateChange()? In OnRender() (not liking this option)? OnMouseDown()?

Thank you

[NinjaTrader_Jim]

Hello neoikon,

Thanks for your question.

It would be appropriate to subscribe to the MarketData event in OnRender when GetAttachedToChartBars gives a valid value and can be used to fetch the instrument. I have attached an example that uses GetAttachedToChartBars in OnRender and subscribes to MarketData events on the first OnRender pass.

Please let us know if we can be of further assistance.