In ServiceNow, debugging server-side scripts can be a challenging task, especially when dealing with complex applications. Fortunately, the Script Tracer tool provides a powerful way to trace and debug these scripts as they execute in real time, making it easier to identify issues and ensure your applications are functioning as expected.
In this article, we’ll walk you through how to use the Script Tracer to debug synchronous server-side scripts, view trace details, and resolve errors effectively.
What is the Script Tracer?
The Script Tracer is a tool within ServiceNow’s Script Debugger that allows you to track the execution of server-side scripts, such as Business Rules, Script Includes, and UI Actions, during specific transactions. By enabling Script Tracing, you can see detailed logs of what happens when a script runs, including the changes to records and any errors that occur.
How to Use the Script Tracer
To get started with the Script Tracer, follow these steps:
1. Opening the Script Tracer
- Navigate to the Script Tracer:
- In the ServiceNow application menu, go to System Diagnostics and then select Script Tracer.
- Start the Trace:
- Once the Script Tracer window is open, click the Start Tracer button to begin capturing script activity.
2. Triggering the Trace
- Perform the Action:
- After starting the trace, return to the form or UI where you want to debug the script. For example, if you’re debugging a UI Action, click the Save or Update button, or perform any other transaction that triggers the server-side script.
- Tracing Begins:
- The Script Tracer will begin recording information as soon as the action takes place. It will capture all relevant server-side scripts and UI Actions that execute during this time.
3. What You See in the Script Tracer
- Once the trace has started, the Script Tracer will display a table with a list of scripts that ran during the trace session. Each row in the table provides detailed information about the transaction.
- File Name: The name of the script file that was executed.
- File Type: Indicates whether the file is a UI Action, Business Rule, Script Include, or another type of script.
- Table: The name of the database table involved in the script execution.
- Line Number: The specific line number in the script where the action took place.
- Errors: If any errors occurred during script execution, they are clearly marked with a red circle and a white X next to the table row.
4. Viewing Trace Details
- To get more information about any specific script, click on the relevant row in the table. This will open the Trace Details panel, which is divided into three tabs:
- State Tab:
- This tab shows the fields and their values for the record being processed by the script. By default, only the changed values are shown, and these are highlighted in green. You can uncheck the Show only changed values option to view all field values for the record.
- This is especially useful for seeing how field values change during script execution, which can help you understand the impact of your script on the record.
- Script Tab:
- Here, you can view the specific line of code that was executed during the trace. To view the complete script, click the Show Script button.
- You also have the option to Debug Script, which opens the Script Debugger and allows you to step through the script line by line.
- If you want to make changes to the script directly, you can click the View File button to open the script in the Now Platform’s script editor.
- Transaction Tab:
- This tab provides information about the transaction itself, giving you additional context on what was happening when the script was executed.
- It’s useful for understanding the broader context in which the script is running and how it affects the application’s behavior.
Key Features of the Script Tracer
Here are some of the main features of the Script Tracer that make it such a valuable tool for debugging:
- Real-Time Script Execution Tracking: The Script Tracer captures the execution of server-side scripts in real time, giving you an accurate log of events as they happen.
- Error Identification: Any errors encountered during the script execution are immediately visible, marked by a red circle with a white X. This makes it easier to pinpoint issues that need attention.
- Detailed Information: The Script Tracer provides detailed information about script execution, including the affected fields, the exact line of script that ran, and details about the transaction.
- Interactive Debugging: With the Debug Script option, you can step through the script interactively, helping you pinpoint exactly where things go wrong.
Troubleshooting with the Script Tracer
When an issue arises, the Script Tracer is an invaluable tool for diagnosing and fixing problems:
Identifying Errors:
- Errors will be marked with a red X in the Script Tracer table. Clicking on the row will show you the specific line of code where the error occurred.
Investigating Field Changes:
- By reviewing the State Tab, you can see exactly what data changed during script execution. This can help you identify unexpected changes or data issues.
Reviewing Script Logic:
- The Script Tab allows you to review the exact script logic executed. If something went wrong, you can debug the script by stepping through it in the Script Debugger to identify any bugs or logic errors.
Testing and Fixing the Issue:
- Once you’ve identified the problem, you can quickly fix the code or data and re-run the test to ensure the issue is resolved.
Conclusion
The Script Tracer is a powerful tool for ServiceNow developers looking to debug and troubleshoot server-side scripts. By providing real-time visibility into script execution, field changes, and transaction details, it streamlines the process of identifying and resolving issues. Whether you’re working with UI Actions, Business Rules, or Script Includes, the Script Tracer is an essential tool in your debugging toolkit.
By following the steps outlined in this article, you can leverage the full capabilities of the Script Tracer to improve your debugging workflow and ensure your ServiceNow applications run smoothly.
