Rectangle code causes error within strategy

[several]

I have the following code inside my indicator, inside OnBarUpdate

Rectangle myRect = Draw.Rectangle(this, "Rectangle" + CurrentBar, false, StartDateTime, High, EndDateTime, Low, Brushes.Silver, Brushes.Silver, 20);

myRect.OutlineStroke = new Stroke(Brushes.Silver, 1);​

When I embed this indicator inside my strategy I found I'm getting an error: "object reference not set to an instance of an object " and it ruins the strategy.

It's this line that's causing the issue: myRect.OutlineStroke = new Stroke(Brushes.Silver, 1);

removing it solves the problem. What should I have done here?

[NinjaTrader_ChelseaB]

Hello several,

The error is indicating a variable (object reference) has a null value (not set to instance of an object).
https://ninjatrader.com/support/helpGuides/nt8/checking_for_null_references.htm?_gl=1*9tfmab*_gcl _au*MTEwNDE0ODg5Ni4xNzQxMTc5ODgz

https://forum.ninjatrader.com/forum/ninjatrader-8/strategy-development/1107472-entryorder-null-error#post1107522

There are a few variables being supplied to the Draw.Rectangle() call which might be null.
The myRect variable might be null if the Draw.Rectangle() call failed.

For the start price (startY) and end price (endY) use High[0] and Low[0].
I'm not certain how this was able to compile at all when using High and Low, as the full series would be the wrong object type (a double is required).

https://developer.ninjatrader.com/docs/desktop/draw_rectangle

Above the Draw.Rectangle() call try printing StartDateTime and EndDateTime to ensure these have values greater than the first bar (Time[CurrentBar]).

https://support.ninjatrader.com/s/article/Developer-Guide-Debugging-using-Print-and-TraceOrders

[several]

Hi, I'm using doubles for the High Low vars passed to the rectangle.

My Print:

StartDateTime = 24/03/2025 09:30:00
EndDateTime = 24/03/2025 09:50:00
CurrentTime = 23/03/2025 18:01:00
Indicator 'OpeningRange2': Error on calling 'OnBarUpdate' method on bar 949: Object reference not set to an instance of an object.

This error does not occur when the indicator is run on it's own. Only within a stratgegy inside strategy analyzer. But it seems to be the line of code with the stroke that causes the error. This line

myRect.OutlineStroke = new Stroke(Brushes.Silver, 1);

I remove this line and no error.

[NinjaTrader_ChelseaB]

Hello several,

The High and Low are variables that hold series objects that are part of the base class of Strategy (or Indicator).

You cannot add your own variables with the same name as the properties provided by the base class as this causes ambiguity.

High is a Series<double> object. High[0] is a double object. By using an index this specifies a specific bar in the series. By not using an index this references the entire series not a specific bar value.

https://developer.ninjatrader.com/docs/desktop/high

https://developer.ninjatrader.com/docs/desktop/low

If you have added your own High and Low variables, you need to rename them to have a new unique name that isn't already used.

That said, is '24/03/2025 09:30:00' greater than the time of CurrentBar 0?
Is '24/03/2025 09:50:00' greater than the time of CurrentBar 0?

The line you are specifying is trying to use the myRect variable. If the Draw tool method call failed, it will return a null.
If you try and use that variable when it is null, it will result in an 'object reference not set to an instance of an object' error.

Something you are passing to the Draw.Rectangle() call is invalid which is resulting in the draw method call failing which causes the myRect variable to be assigned null which results in the error when trying to use that variable.

Now that you have stated that 'I'm using doubles for the High Low vars passed to the rectangle.' this is now where my suspicion is.

High and Low are series not doubles. High[0] and Low[0] are doubles.
Did you define your own High and Low variables?

[several]

Sorry, I didn't mean to confuse but I have unique variable names for the High and Low. ORHigh and ORLow.

At 9:50 I draw a rectangle around the bars from 9:30 to 9:50.

The indicator works fine, on it's own. Just when I enter it in a strategy I get this error.

[NinjaTrader_ChelseaB]

Hello several,

Are you providing different code than what is actually being run in the script?

The specifics do make a difference.

Is the indicator setting a plot value and the strategy using the plot value? (calling series values causes OnBarUpdate() to run in the indicator)

[several]

This is exactly the code:

                Rectangle myRect = Draw.Rectangle(this, "OR Rectangle" + CurrentBar, false, StartDateTime, ORHigh, EndDateTime, ORLow, Brushes.Silver, Brushes.Silver, 20);
                myRect.OutlineStroke = new Stroke(Brushes.Silver, 1);    ​

I'm not using any plot. I simply seek to use ORHigh / ORLow exposed to the strategy. It works if I remove the line relating to the stroke.

[NinjaTrader_ChelseaB]

Hello several,

Add a plot with AddPlot() even if you do not plan to use it.

Set any value to the plot (like CurrentBar or 0) by assigning Value[0] to something.

https://support.ninjatrader.com/s/article/Developer-Guide-Adding-Plots-in-Indicators

Call the plot value from the strategy. (For example assign the plot value to a variable and just don't use the variable)

This should trigger OnBarUpdate() to run internally in the indicator to call the draw methods in the correct sequence.

Again, you will want to ensure that any date used for the start and end dates has a date and time greater than bar 0.

Let me know if this does not correct the error.

[several]

I tried this but I must be doing something wrong. I get now 2 errors.

In the indicator:

 // State.Configure
 AddPlot(Brushes.Blue, "SignalPlot");

//OnBarUpdate
            if (
                (Times[1][0] == StartDateTime)
                && (BarsInProgress == 1)
                )
            {
                                SignalPlot[0] = CurrentBar;
}

// properties
        [Browsable(false)]
        [XmlIgnore]
        public Series<double> SignalPlot
        { get { return Values[0]; }}​​


​

Now in the strategy:

            if (
                ((Times[0][0].TimeOfDay == EndTime.TimeOfDay))
                )
            {
                varplot = OR2.SignalPlot[0];
//Draw rectangle code here
            }    ​

I got both the original error plus an index invalid error:

Indicator 'OpeningRange2': Error on calling 'OnBarUpdate' method on bar 949: Object reference not set to an instance of an object.
Strategy 'StratOpeningRange': Error on calling 'OnBarUpdate' method on bar 1378: You are accessing an index with a value that is invalid since it is out-of-range. I.E. accessing a series [barsAgo] with a value of 5 when there are only 4 bars on the chart.
​
​

And FYI this is how I'm getting the start/end times to draw the rectangle in the indicator:

//set defaults
                Time1                                        = DateTime.Parse("09:30", System.Globalization.CultureInfo.InvariantCulture);
                Time2                                        = DateTime.Parse("09:50", System.Globalization.CultureInfo.InvariantCulture);
​
//onbarupdate

            StartDateTime = new DateTime(Times[1][0].Year, Times[1][0].Month, Times[1][0].Day, Time1.Hour, Time1.Minute, 0);
            EndDateTime = new DateTime(Times[1][0].Year, Times[1][0].Month, Times[1][0].Day, Time2.Hour, Time2.Minute, 0);    ​

The data series 1 is simply a 1 minute series.

[NinjaTrader_ChelseaB]

Hello several,

Remove the conditions.

Assign the SignalPlot[0] on every bar update without a condition in the indicator.

Call the SignalPlot[0] on every bar update without a condition in the strategy.

Temporarily comment out the Draw tool method call.

Confirm the error no longer occurs.