NinjaScript Patterns

Lightweight scaffold for NinjaTrader 8 NinjaScript/C# indicator development.

Before Generating Code

ALWAYS use doc-researcher agent or Ref MCP tools to verify:

• NinjaTrader 8 API methods

• Property attribute usage

• Drawing object APIs

File Conventions

• File naming: *LB.cs

• Author: // Author: Luther Barnum

Namespace & Class

namespace NinjaTrader.NinjaScript.Indicators.LB { public class [Name]LB : Indicator { // Implementation } }

Lifecycle Methods

OnStateChange()

protected override void OnStateChange() { if (State == State.SetDefaults) { Description = "Indicator description"; Name = "IndicatorName"; // Set property defaults } else if (State == State.Configure) { AddPlot(Brushes.Blue, "PlotName"); } else if (State == State.DataLoaded) { // Initialize Series objects } }

OnBarUpdate()

protected override void OnBarUpdate() { if (CurrentBar < BarsRequiredToPlot) return; // Calculations }

Property Attributes

[NinjaScriptProperty] [Display(Name = "Period", Order = 1, GroupName = "Parameters")] [Range(1, int.MaxValue)] public int Period { get; set; }

Session Detection

if (Bars.IsFirstBarOfSession) { // Reset session values }

Series Objects

private Series<double> myValues;

// In State.DataLoaded: myValues = new Series<double>(this);

Drawing Objects

Draw.Rectangle(this, "tag", startBar, startPrice, endBar, endPrice, Brushes.Blue); Draw.Line(this, "tag", startBar, startPrice, endBar, endPrice, Brushes.Red); Draw.Text(this, "tag", "Label", 0, High[0] + TickSize, Brushes.White);

Complete Example

Reference: /Users/lgbarn/Personal/Indicators/Ninjatrader/PEMA.cs

#region Using declarations using System; using System.ComponentModel; using System.ComponentModel.DataAnnotations; using System.Windows.Media; using NinjaTrader.Gui.Chart; using NinjaTrader.NinjaScript.DrawingTools; #endregion

// Author: Luther Barnum

namespace NinjaTrader.NinjaScript.Indicators.LB { public class SimpleMALB : Indicator { private EMA fastEma; private SMA slowSma;

    protected override void OnStateChange()
    {
        if (State == State.SetDefaults)
        {
            Description = "Simple MA Crossover Indicator";
            Name = "SimpleMALB";
            Calculate = Calculate.OnBarClose;
            IsOverlay = true;

            // Default parameters
            FastPeriod = 9;
            SlowPeriod = 21;

            // Add plots
            AddPlot(Brushes.Cyan, "FastMA");
            AddPlot(Brushes.Orange, "SlowMA");

            Plots[0].Width = 2;
            Plots[1].Width = 2;
        }
        else if (State == State.DataLoaded)
        {
            fastEma = EMA(Close, FastPeriod);
            slowSma = SMA(Close, SlowPeriod);
        }
    }

    protected override void OnBarUpdate()
    {
        if (CurrentBar < SlowPeriod)
            return;

        FastMA[0] = fastEma[0];
        SlowMA[0] = slowSma[0];
    }

    #region Properties
    [NinjaScriptProperty]
    [Range(1, int.MaxValue)]
    [Display(Name = "Fast Period", Order = 1, GroupName = "Parameters")]
    public int FastPeriod { get; set; }

    [NinjaScriptProperty]
    [Range(1, int.MaxValue)]
    [Display(Name = "Slow Period", Order = 2, GroupName = "Parameters")]
    public int SlowPeriod { get; set; }

    [Browsable(false)]
    [XmlIgnore]
    public Series<double> FastMA { get { return Values[0]; } }

    [Browsable(false)]
    [XmlIgnore]
    public Series<double> SlowMA { get { return Values[1]; } }
    #endregion
}

}

VWAP Calculation Pattern

private double cumVolume; private double cumVwap; private double cumVwap2;

protected override void OnBarUpdate() { if (Bars.IsFirstBarOfSession) { cumVolume = 0; cumVwap = 0; cumVwap2 = 0; }

double typicalPrice = (High[0] + Low[0] + Close[0]) / 3.0;
cumVolume += Volume[0];
cumVwap += Volume[0] * typicalPrice;
cumVwap2 += Volume[0] * typicalPrice * typicalPrice;

if (cumVolume > 0)
{
    double vwap = cumVwap / cumVolume;
    double variance = (cumVwap2 / cumVolume) - (vwap * vwap);
    double stdev = variance > 0 ? Math.Sqrt(variance) : 0;

    VWAP[0] = vwap;
    UpperBand[0] = vwap + stdev;
    LowerBand[0] = vwap - stdev;
}

}

Error Handling Patterns

Check bar history

protected override void OnBarUpdate() { // Ensure enough bars for calculation if (CurrentBar < BarsRequiredToPlot) return;

// Or use specific period
if (CurrentBar < Period - 1)
    return;

}

Null/zero checks

// Safe division double divisor = High[0] - Low[0]; double result = divisor != 0 ? (Close[0] - Low[0]) / divisor : 0.5;

// Check indicator values if (myIndicator[0] != 0 && !double.IsNaN(myIndicator[0])) { // Safe to use }

Validate parameters

if (State == State.SetDefaults) { // Use [Range] attribute for validation } else if (State == State.Configure) { // Additional validation if (SlowPeriod <= FastPeriod) SlowPeriod = FastPeriod + 1; }

Historical data access

// Safe access to previous bars if (CurrentBar >= barsAgo) { double previousValue = Close[barsAgo]; }

Trading Context

• Focus: /ES, /NQ futures

• Timeframe: 5-minute

• Key concepts: VWAP+bands, IB, Pivots

• Location: /Users/lgbarn/Personal/Indicators/Ninjatrader/

Documentation Sources

Use Ref MCP to search:

• NinjaTrader 8 Help Guide

• NinjaScript Reference