Python is used in many parts of the ArcGIS Pro application. Integrated development environments (IDEs) are applications that provide editing and debugging functionality for code writers. IDEs make the writing and troubleshooting of code more efficient. Python IDEs can be used to author and troubleshoot script tool and Python toolbox validation and execution code.
Microsoft Visual Studio
The following ArcGIS Pro components can be debugged in Visual Studio:
- Script tool Execution
- Script tool Validation
- Python toolboxes
The following Visual Studio workload must be installed: Python development. See https://docs.microsoft.com/en-us/visualstudio/install/modify-visual-studio.
To start debugging Python code in ArcGIS Pro, use the following steps:
- In ArcGIS Pro, open the Geoprocessing pane of the tool to be debugged.
The Python window and any notebooks must be closed.
- Start Microsoft Visual Studio and open the script to be debugged.
- On the main menu, click Debug > Attach to Process.
- On the Attach to Process dialog box, click the Select button.
- On the Select Code Type dialog box, check Debug these code types, check Python, and click OK.
You must choose Attach to: Python code. Do not use the default code type of Automatic: Managed (v4.6, v4.5, v4.0) code, Python code.
- In the list of available processes, click the ArcGISPro.exe process and click the Attach button.
- Run your tool in ArcGIS Pro to start debugging.
After detaching the IDE from ArcGIS Pro, exceptions in Python code will not display correctly. To address this, either reattach the IDE or restart ArcGIS Pro.
Microsoft Visual Studio 2017 can be used to debug ArcGIS Pro 2.1 and later. Earlier versions of either of these applications will not work.
PyCharm Professional edition
The following ArcGIS Pro components can be debugged in PyCharm Professional edition:
- Script tool Execution
- Script tool Validation
The pdb module is part of the Python standard library. It is not a fully developed IDE, but it can be used for interactive source code debugging. The pdb module cannot be used to debug within ArcGIS Pro, but it can be used to debug stand-alone scripts, including the execution code for script tools.
Using the pdb module is useful for debugging a script tool's execution code running in a stand-alone Python script. Add a breakpoint (using import pdb;pdb.set_trace()) into your script tool's code, and run a Python script that calls that script tool. Upon encountering the breakpoint, Python will enter interactive mode. Remember to remove the breakpoint code upon completion of the debugging effort.
Debug script tool validation code
IDEs can only debug Python files (.py). For Python code in script tool validation (embedded in a toolbox), copy the code to an external Python file and replace the code in the Python toolbox with the example below. You can then open the Python file in your IDE and set breakpoints, attach the IDE to ArcGIS Pro, and run your script tool. Upon completion of code modification, copy the contents of the Python file back into the tool validation.
In the following example, val.py contains the ToolValidator class and is saved to the same directory as the toolbox.
import sys import val # the following code will reload the val.py module if it's modified if 'val' in sys.modules: import importlib importlib.reload(val) # ToolValidator should exist at the global scope ToolValidator = val.ToolValidator
The validation code in script tool validation is run repeatedly as a user interacts with a tool.
Debug Python toolboxes
IDEs can only debug Python files (.py). Follow these steps to debug a Python toolbox.
- Create an external Python file within the same directory as the Python toolbox.
- Copy the code within the execute function of the Python toolbox and paste it into a function func() in the new Python file. Copy over any other necessary functions.
- Replace the code in the Python toolbox execute function with the following:
- Open the Python file in Visual Studio and set breakpoints using the steps above to debug the Python toolbox.
import execute_code execute_code.func(parameters)
The following code is an example of the execute function in the Python toolbox and the separate Python file being called.
In the following example, runCode.py is saved to the same directory as a .pyt file.
import arcpy def func(parameters): arcpy.AddMessage("This is where your code execution goes.") return
The following is an example of the modified execute function in a Python toolbox.
def execute(self, parameters, messages): """The source code of the tool.""" import runCode runCode.func(parameters) return
Upon completion of code modification, copy the contents of the Python file back into the tool's execute function.