casting error?

[NinjaTrader_ChelseaB]

Hello td_910,

Syntax errors do not cause run-time errors. Syntax errors cause compile errors.

You are experiencing a run-time error, you are not experiencing a compile error.

No, I do not see any errors with syntax.

What is the exact line causing the run-time error?

Are you able to reproduce using the test script I have provided you?

If the error is not being produced when refreshing the chart, when is the error being produced?

[td_910]

Hello td_910,

Syntax errors do not cause run-time errors. Syntax errors cause compile errors.

You are experiencing a run-time error, you are not experiencing a compile error.

No, I do not see any errors with syntax.

What is the exact line causing the run-time error?

Are you able to reproduce using the test script I have provided you?

If the error is not being produced when refreshing the chart, when is the error being produced?

yes, I know, I meant the syntax for the dynamic object handling and dynamic object properties
the script runs without errors on the same chart

[td_910]

looking at that code, there should all errors been taken care of
even checking twice, that the objects are not null before accessing them

what exactly does the error msg mean?

this stuff is delaying the launch of my website since two weeks
all NT7 versions of my indicators run without any errors, but I want to start providing version 8 indicators as well

[td_910]

2019-03-26 17:15:00:411|3|4|Indicator 'PASuppResBreakoutTest': Error on calling 'OnBarUpdate' method on bar 1167:

[A]NinjaTrader.NinjaScript.DrawingTools.Line cannot be cast to
[B]NinjaTrader.NinjaScript.DrawingTools.Line.

Type A originates from '99e5424db07446b8aa696f44becabc5c, Version=8.0.17.2, Culture=neutral, PublicKeyToken=null' in the context 'LoadFrom' at location 'C:\Users\Thomas\Documents\NinjaTrader 8\tmp\99e5424db07446b8aa696f44becabc5c.dll'.

Type B originates from 'cce54770972f475cb2d53c957eb5d606, Version=8.0.17.2, Culture=neutral, PublicKeyToken=null' in the context 'LoadFrom' at location 'C:\Users\Thomas\Documents\NinjaTrader 8\tmp\cce54770972f475cb2d53c957eb5d606.dll'.

both DLLs and the corresponding XML files have the same size, the XML files are the same and the DLLs have a handful of differences only (using FC)

https://www.screencast.com/t/pwX0naIZmUGg

[NinjaTrader_ChelseaB]

Hello td_910,

I notice you are still casting instead of using the dynamic object.

In the example I have provided you, the dynamic object is used.


The error is telling you that this object exists in two places and the object being used isn't the original.

NinjaTrader takes the code you have written and then compiles it as part of the internal code. I can't get into much detail with this internal process but its the reason the dynamic keyword must be used when making a dll.

The dynamic keyword basically means, hey its the same class please don't care where it came from.

Below is a link to the microsoft documentation.

https://docs.microsoft.com/en-us/dotnet/csharp/programming-guide/types/using-type-dynamic

If the script I have provided for you doesn't reproduce, this could be a good place to start from.

At this point you have not provided enough information for some to assist, unless they have a specific example of where they have run into this before and gotten around it.


It would save considerable time if we didn't have to guess which line is the issue and you could tell us the exact problem and the exact line of code.
You can use prints to find the exact line of code as I have previously recommended.

[td_910]

I think I misunderstood your 1st proposal
I thought one has to use dynamic type, then check if it's the wanted type, then cast and then access object properties
Sorry, I'm a trader and no programmer

there is one step to much, the cast :-)

this should do the trick?

            #region delete line two and three bars back
            if (IsFirstTickOfBar)
            {
                if (DrawObjects["BT_Swing_Low"+unique+(CurrentBar-2)] != null && DrawObjects["BT_Swing_Low"+unique+(CurrentBar-1)] != null)
                {
                    dynamic BT_Swing_Low1 = DrawObjects["BT_Swing_Low"+unique+(CurrentBar-1)];
                    dynamic BT_Swing_Low2 = DrawObjects["BT_Swing_Low"+unique+(CurrentBar-2)];

                    if (BT_Swing_Low1.ToString().Equals("NinjaTrader.NinjaScript.DrawingTools.Line") &&
                        BT_Swing_Low2.ToString().Equals("NinjaTrader.NinjaScript.DrawingTools.Line"))
                    {
                        //BT_Swing_Low1 = (NinjaTrader.NinjaScript.DrawingTools.Line) DrawObjects["BT_Swing_Low"+unique+(CurrentBar-1)];
                        //BT_Swing_Low2 = (NinjaTrader.NinjaScript.DrawingTools.Line) DrawObjects["BT_Swing_Low"+unique+(CurrentBar-2)];

                        if (BT_Swing_Low1 != null && BT_Swing_Low2 != null &&
                            BT_Swing_Low1.StartAnchor.BarsAgo == BT_Swing_Low2.StartAnchor.BarsAgo+1 &&
                            BT_Swing_Low1.StartAnchor.Price   == BT_Swing_Low2.StartAnchor.Price)

                            RemoveDrawObject("BT_Swing_Low"+unique+(CurrentBar-2));
                    }
                }
                if (DrawObjects["BT_Swing_Low"+unique+(CurrentBar-3)] != null && DrawObjects["BT_Swing_Low"+unique+(CurrentBar-1)] != null)
                {
                    dynamic BT_Swing_Low1 = DrawObjects["BT_Swing_Low"+unique+(CurrentBar-1)];
                    dynamic BT_Swing_Low2 = DrawObjects["BT_Swing_Low"+unique+(CurrentBar-3)];

                    if (BT_Swing_Low1.ToString().Equals("NinjaTrader.NinjaScript.DrawingTools.Line") &&
                        BT_Swing_Low2.ToString().Equals("NinjaTrader.NinjaScript.DrawingTools.Line"))
                    {
                        //BT_Swing_Low1 = (NinjaTrader.NinjaScript.DrawingTools.Line) DrawObjects["BT_Swing_Low"+unique+(CurrentBar-1)];
                        //BT_Swing_Low2 = (NinjaTrader.NinjaScript.DrawingTools.Line) DrawObjects["BT_Swing_Low"+unique+(CurrentBar-3)];

                        if (BT_Swing_Low1 != null && BT_Swing_Low2 != null &&
                            BT_Swing_Low1.StartAnchor.BarsAgo == BT_Swing_Low2.StartAnchor.BarsAgo+2 &&
                            BT_Swing_Low1.StartAnchor.Price   == BT_Swing_Low2.StartAnchor.Price)

                            RemoveDrawObject("BT_Swing_Low"+unique+(CurrentBar-3));
                    }
                }
            }
            #endregion

[NinjaTrader_ChelseaB]

Hello td_910,

Yes, with those lines commented out I would not be expecting casting errors.

Was this posted because you are still getting an casting error?

[td_910]

Hello td_910,

Yes, with those lines commented out I would not be expecting casting errors.

Was this posted because you are still getting an casting error?

Everything is fine now, thanks for your patience.

[td_910]

I have Visual Studio running in the background all day and caught this

And I thought the null checks were safe

[NinjaTrader_ChelseaB]

Hello td_910,

Thank you for your note.

Null checks are safe if the index is valid or when using a variable that is not a collection.

The issue is that a tag is used as the index to find an element in a collection that was modified.
This likely means an object was removed from the collection which modified the collection.

What version of NinjaTrader 8 are you using?


Are there multiple instances of the script added to the chart?
https://ninjatrader.com/support/foru...417#post805417


Below is a link to a post that describes making a copy of the collection with ToList() as the copy will not be modified.
https://ninjatrader.com/support/foru...754#post811754

Using a for loop would also work to prevent the error.

[td_910]

Hi Chelsea,

I'm using NT 8.0.17.2 64-bit.

Yes there are multiple instances of the indicator on that chart (2).

I'm already using a unique string to separate the drawing objects

                //unique identifier
                unique = BarsPeriod.Value.ToString("N") + Guid.NewGuid().ToString("N");

This is a snippet of an if statement of another indicator. How would I use a thread safe list copy with this many objects (OnPriceChange)?

                //prior opposite signal
                DrawObjects["Thumbs_DT"+(CurrentBar-2)] == null && DrawObjects["Thumbs_DT"+(CurrentBar-1)] == null && DrawObjects["Thumbs_DT"+(CurrentBar)] == null &&
                DrawObjects["Thumbs_TT"+(CurrentBar-2)] == null && DrawObjects["Thumbs_TT"+(CurrentBar-1)] == null &&  DrawObjects["Thumbs_TT"+(CurrentBar)] == null &&
                !(DrawObjects["Thumbs_mDT"+(CurrentBar-1)] != null && Bars.BarsSinceSession>8 && MAX(High,2)[4]<High[3]) &&

                //prior bar and current are thumbs already
                (DrawObjects["Thumbs_mDB"+(CurrentBar-1)] == null || Low[2]!=Low[1]) &&
                DrawObjects["Thumbs_DB"+(CurrentBar)] == null && DrawObjects["Thumbs_TB"+(CurrentBar)] == null)

[NinjaTrader_ChelseaB]

Hello td_910,

Below is how a list copy of the collection can be made.

List<IDrawingTool> objs = DrawObjects.ToList();
for(int i = 0; i < objs.Count; i++)
{
IDrawingTool obj = objs[i];
Print(obj.GetType().Name);
}

[td_910]

Hello td_910,

Below is how a list copy of the collection can be made.\

List<IDrawingTool> objs = DrawObjects.ToList();
for(int i = 0; i < objs.Count; i++)
{
IDrawingTool obj = objs[i];
Print(obj.GetType().Name);
}

And how would I use that in that example if statement?

 //prior opposite signal
DrawObjects["Thumbs_DT"+(CurrentBar-2)] == null && DrawObjects["Thumbs_DT"+(CurrentBar-1)] == null && DrawObjects["Thumbs_DT"+(CurrentBar)] == null &&
DrawObjects["Thumbs_TT"+(CurrentBar-2)] == null && DrawObjects["Thumbs_TT"+(CurrentBar-1)] == null && DrawObjects["Thumbs_TT"+(CurrentBar)] == null &&
!(DrawObjects["Thumbs_mDT"+(CurrentBar-1)] != null && Bars.BarsSinceSession>8 && MAX(High,2)[4]<High[3]) &&

//prior bar and current are thumbs already
(DrawObjects["Thumbs_mDB"+(CurrentBar-1)] == null || Low[2]!=Low[1]) &&
DrawObjects["Thumbs_DB"+(CurrentBar)] == null && DrawObjects["Thumbs_TB"+(CurrentBar)] == null)

[td_910]

        // Loops through the DrawObjects collection via a threadsafe list copy
        public string DrawObjectsCheck(string DrawObjectTag)
        {
            foreach(var tool in DrawObjects.ToList())
            {
                if (tool.Tag == DrawObjectTag)
                {
                    return DrawObjectTag;
                }
            }
            return null;
        }

using that method, this

[FONT=arial]DrawObjects["Thumbs_DT"+(CurrentBar-2)] == null && [/FONT]

becomes that

DrawObjectsCheck("Thumbs_DT"+(CurrentBar-2)) == null &&

???

[NinjaTrader_ChelseaB]

Hello td_910,

private string unique = string.Empty;
private int barIndex;

In OnStateChange():
else if (State == State.DataLoaded)
{
    unique    = Guid.NewGuid().ToString();
}

In OnBarUpdate():
// draw a dot
if (State == State.Historical && CurrentBar == Count - 10)
{
    Draw.Dot(this, string.Format("dot{0}{1}", unique, CurrentBar), true, 0, High[0] + 3 * TickSize, Brushes.Blue);
    barIndex = CurrentBar;
}

loop through a copy of the drawing objects collection (which won't be modified while we're looping)
List<IDrawingTool> objs = DrawObjects.ToList();
for (int i = 0; i < objs.Count; i++)
{
    IDrawingTool obj = objs[i];
    Print(obj.Tag);

    Print(string.Format("dot{0}{1}\r\n", unique, barIndex));
// if its the drawing object i was looking for, remove it
    if (obj.Tag == string.Format("dot{0}{1}", unique,  barIndex))
        RemoveDrawObject(obj.Tag);
}