Save/Restore BarsPeriod

[aslane]

I have an AddOn that uses an IntervalSelector similar to the AddOnFramewoek example. I have been trying to save/restore the corresponding BarsPeriod. I am using the BarsPeriod.ToXml method to save, and the FromXml method to restore. The problem I am running into is the ToXml method seems to be only saving the value and not the entire BarsPeriod. For example, if I set to 1000 volume, and save, it is saving 1000 minute in the resulting xml, and the restore restores that instead of the original.

You can see the issue if you add the following code to the AddOnFramework example

//  add to: protected override void Restore(XElement element)

            // Restore the previously selected interval
            BarsPeriod barsPeriod = NinjaTrader.Data.BarsPeriod.FromXml(element);

            if (intervalSelector != null && barsPeriod != null)
                intervalSelector.Interval = barsPeriod;


// add to: protected override void Save(XElement element)

            // Save the currently selected interval
            if (BarsPeriod != null)
                BarsPeriod.ToXml(element);

Am I doing something wrong or is there an issue in ToXml()?

Also, would be nice if this was added properly to the example. Thanks.

[NinjaTrader_ChelseaB]

Hello aslane,

The issue is that a BarsPeriod class is not easily converted to a string.

Try saving the BarsPeriod.Id and BarsPeriod.Value individually instead, and then instantiate a new BarsPeriod using the saved Id and Value.

Also, below is a link to an example of workspace persistence you may find helpful.

https://ninjatrader.com/support/forum/forum/ninjatrader-8/add-on-development/98812-how-to-save-restore-an-intervalselector-value?p=790447#post790447

[aslane]

So in other words, ToXml doesn't work

[NinjaTrader_ChelseaB]

Hello aslane,

ToXml() works for anything easily converted to a string.

This is the same for inputs in an indicator or strategy that need serializing. (NinjaTrader uses the ToXml() on NinjaScript properties that are easily converted to strings. Things that are not easily converted to strings have to be converted to a string first, before it can be saved.)

https://ninjatrader.com/support/help...definedbrushes

[aslane]

Ok, I understand now. I thought this was a specific method of BarsPeriod. I will implement my own. Thanks.

[aslane]

Just for others, you can save/restore by doing some quick casting. You can use something like the following to save:

        private void SaveBarPeriod(XElement element)
        {
            if (BarsPeriod == null)
                return;

            XElement bpElement = new XElement("BarsPeriod");

            bpElement.Add(new XElement("BaseBarsPeriodType") { Value = ((int)BarsPeriod.BaseBarsPeriodType).ToString() });
            bpElement.Add(new XElement("BaseBarsPeriodValue") { Value = BarsPeriod.BaseBarsPeriodValue.ToString() });
            bpElement.Add(new XElement("BarsPeriodType") { Value = ((int)BarsPeriod.BarsPeriodType).ToString() });
            bpElement.Add(new XElement("MarketDataType") { Value = ((int)BarsPeriod.MarketDataType).ToString() });
            bpElement.Add(new XElement("PointAndFigurePriceType") { Value = ((int)BarsPeriod.PointAndFigurePriceType).ToString() });
            bpElement.Add(new XElement("ReversalType") { Value = ((int)BarsPeriod.ReversalType).ToString() });
            bpElement.Add(new XElement("Value") { Value = BarsPeriod.Value.ToString() });
            bpElement.Add(new XElement("Value2") { Value = BarsPeriod.Value2.ToString() });

            element.Add(bpElement);
        }

You can restore with something like:

        private void RestoreBarPeriod(XElement topElement)
        {
            try
            {
                if (BarsPeriod == null)
                    return;

                XElement bpElement = topElement.Element("BarsPeriod");

                if (bpElement == null)
                    return;

                XElement element;

                BarsPeriod barsPeriod = new BarsPeriod();

                element = bpElement.Element("BarsPeriodType");
                if (element != null)
                    barsPeriod.BarsPeriodType = (BarsPeriodType)int.Parse(element.Value);
                else
                    return;    // no period type not ok

                element = bpElement.Element("BaseBarsPeriodType");
                if (element != null)
                    barsPeriod.BaseBarsPeriodType = (BarsPeriodType)int.Parse(element.Value);

                element = bpElement.Element("BaseBarsPeriodValue");
                if (element != null)
                    barsPeriod.BaseBarsPeriodValue = int.Parse(element.Value);

                element = bpElement.Element("MarketDataType");
                if (element != null)
                    barsPeriod.MarketDataType = (MarketDataType)int.Parse(element.Value);

                element = bpElement.Element("PointAndFigurePriceType");
                if (element != null)
                    barsPeriod.PointAndFigurePriceType = (PointAndFigurePriceType)int.Parse(element.Value);

                element = bpElement.Element("ReversalType");
                if (element != null)
                    barsPeriod.ReversalType = (ReversalType)int.Parse(element.Value);

                element = bpElement.Element("Value");
                if (element != null)
                    barsPeriod.Value = int.Parse(element.Value);

                element = bpElement.Element("Value2");
                if (element != null)
                    barsPeriod.Value2 = int.Parse(element.Value);

                if (intervalSelector != null)
                    intervalSelector.Interval = barsPeriod;            
            }
            catch (Exception ex)
            {
                // LogError("Problem restoring BarsPeriod, ex= "+ex);
            }
        }

There are some assumptions in above code (geared toward the AddOnFramework example) and there may be better ways to do, but wanted to provide for anyone looking for a start.

[NinjaTrader_ChelseaB]

Hello aslane,

Thank you for posting your solution.

The community may find this very helpful.