topic Re: How to return value from ArcGIS Pro custom tool (.py)? in ArcGIS Pro Questions

How to return value from ArcGIS Pro custom tool (.py)?

uasdev — Thu, 29 Feb 2024 22:55:06 GMT

How do we return a value from a custom .py tool, so that when I run the tool in another script, it will return a value (such as a number, string, or tuple)?

Notice in the execute class function, I attempt to return a tuple of values. However, when I run the tool in a separate script, the return value is empty.

I use the following code to import the toolbox and run the code:

```

arcpy.ImportToolbox(pyt_path, "myToolbox")

arcpy.myToolbox.HelloWorld()

```

Below is an example .py script for the tool above

```

import arcpy

from multiprocessing import Pool

class HelloWorld(object):

def __init__(self):

"""Define the tool (tool name is the name of the class)."""

self.label = "Hello World"

self.description = ""

self.canRunInBackground = False

def getParameterInfo(self):

"""Define parameter definitions"""

params = None

return params

def isLicensed(self):

"""Set whether tool is licensed to execute."""

return True

def updateParameters(self, parameters):

"""Modify the values and properties of parameters before internal

validation is performed. This method is called whenever a parameter

has been changed."""

return

def updateMessages(self, parameters):

"""Modify the messages created by internal validation for each tool

parameter. This method is called after internal validation."""

return

def execute(self, parameters, messages):

"""The source code of the tool."""

arcpy.AddMessage("Hello World!")

# arcpy.AddMessage("Hello Jupiter!")

return ("Hello world", 1, True)

def postExecute(self, parameters):

"""This method takes place after outputs are processed and

added to the display."""

return

```

Re: How to return value from ArcGIS Pro custom tool (.py)?

GeeteshSingh07 — Fri, 01 Mar 2024 04:28:05 GMT

Hi @uasdev, this is how I execute my codes:

The following is my .py file:

import arcpy class Toolbox: def __init__(self): """Define the toolbox (the name of the toolbox is the name of the .pyt file).""" self.label = "Toolbox" self.alias = "toolbox" # List of tool classes associated with this toolbox self.tools = [HelloWorld] class HelloWorld: def __init__(self): self.label = "HelloWorld" self.description = "" def getParameterInfo(self): """Define the tool parameters.""" params = None return params def isLicensed(self): """Set whether the tool is licensed to execute.""" return True def updateParameters(self, parameters): """Modify the values and properties of parameters before internal validation is performed. This method is called whenever a parameter has been changed.""" return def updateMessages(self, parameters): """Modify the messages created by internal validation for each tool parameter. This method is called after internal validation.""" return def execute(self, parameters, messages): """The source code of the tool.""" out_str = "This is String" out_tuple = [1,2,3,4,5] arcpy.AddMessage("Hello") print(out_str, out_tuple) def postExecute(self, parameters): """This method takes place after outputs are processed and added to the display.""" return

If you want to print, string/tuple or any other data type:

If you want to return arcpy.message, then, instead of 'print', use 'return':

def execute(self, parameters, messages): """The source code of the tool.""" out_str = "This is String" out_tuple = [1,2,3,4,5] arcpy.AddMessage("Hello") return

How did I debug?

Using return statement, python understands there is an output, but it returns empty.

I am not sure, if this is expected behavior or not, but this is how I run my code.

Best, Geetesh

Re: How to return value from ArcGIS Pro custom tool (.py)?

uasdev — Fri, 01 Mar 2024 16:52:16 GMT

Thanks Geetesh! This should work for my application.

Appreciate the help.

Best,

Alex

Re: How to return value from ArcGIS Pro custom tool (.py)?

GeeteshSingh07 — Fri, 01 Mar 2024 17:44:33 GMT

That's great! @uasdev

Re: How to return value from ArcGIS Pro custom tool (.py)?

uasdev — Fri, 15 Mar 2024 19:36:27 GMT

HI @GeeteshSingh07 , this option does not work for me. The return value is None when I try to return variables within the execute function in arcgis tool.