NinjaTrader

Using the NinjaScript Editor

Paste your code, compile with F5, and run it

The NinjaScript Editor is where NinjaTrader 8 turns your code into a working indicator or strategy. This guide shows how to open it, paste the code you copied from HorizonAI, compile it, deal with common errors, and add the result to a chart.

In HorizonAI, click Copy Code in the chat header to copy your NinjaScript to the clipboard first. There's no download for NinjaScript — you'll paste directly into the editor.

1) Open the NinjaScript Editor

From the Control Center, go to New → NinjaScript Editor (you can also reach it from Tools → NinjaScript Editor). The editor opens in its own window.

2) Create a new indicator or strategy

Your generated code already contains a full class. Create a matching file for it:

  1. In the NinjaScript Editor, click New and choose Indicator or Strategy — pick whichever matches your code. (HorizonAI-generated indicators derive from Indicator; strategies derive from Strategy and use EnterLong() / EnterShort() calls.)
  2. The NinjaScript Wizard asks for a name. Name it to match the class name in your generated code — e.g. if the code says public class EmaCross : Strategy, name it EmaCross.
  3. Finish the wizard. NinjaTrader creates a template file with some starter code.

The file name must match the class name inside the code, or it won't compile. If your generated code declares public class MyStrategy, the file has to be MyStrategy. Rename one to match the other if they differ.

3) Paste your HorizonAI code

Select all of the template code the wizard generated (Ctrl+A) and replace it by pasting your copied HorizonAI code (Ctrl+V). You want the pasted code to be the entire contents of the file — including its using statements and namespace — not appended to the template.

4) Compile

Compile the code in any of these ways:

  • Press F5, or
  • Click the Compile button on the editor toolbar, or
  • Right-click in the editor and choose Compile.

On success, NinjaTrader converts your code into a native C# assembly and your script is ready to use. If anything is wrong, compile errors appear at the bottom of the editor with the file and line number.

Save with Ctrl+S before compiling. A clean compile with no errors listed at the bottom means your indicator or strategy is now available in the platform.

Where your compiled script lands

NinjaTrader files your script by its base class automatically:

  • Indicators (deriving from Indicator, namespace NinjaTrader.NinjaScript.Indicators) appear in the chart's Indicators list.
  • Strategies (deriving from Strategy, namespace NinjaTrader.NinjaScript.Strategies) appear in the chart's Strategies list and in the Strategy Analyzer.

Add an indicator to a chart

  1. Open the chart you want to use.
  2. Right-click the chart and choose Indicators (or press Ctrl+I).
  3. Find your indicator by name in the Available list, select it, and click Add.
  4. Adjust any inputs on the right, then click OK. It plots on the chart in real time.

Apply a strategy

To run a strategy live-in-simulation, right-click a chart and choose Strategies, add yours, set its account to your simulation account, and enable it. To test it on historical data instead, use the Strategy Analyzer — see Backtesting in NinjaTrader.

Fixing common compile errors

If the compile fails, read the message at the bottom of the editor — it names the line. A few things that trip up pasted code:

  • File name ≠ class name. The .cs file must be named exactly like the public class in the code.
  • Duplicate name. If a script with that name already exists, rename your new one (and its class) to something unique.
  • Missing using or namespace. Make sure you pasted the whole script, including the using block and namespace at the top — don't paste just the class body over the template.
  • Indicator vs. strategy mismatch. Trading calls like EnterLong() only exist on a Strategy. If you created an Indicator file but the code is a strategy, recreate it as a Strategy (or ask HorizonAI to regenerate it as the type you want).

Stuck on an error? Copy the exact message, paste it back into your HorizonAI chat, and ask the AI to fix it. It knows the NinjaScript it wrote and can correct the offending line.

Next steps

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