topic Reprojecting an Extent object in a Python Toolbox in Python Questions

Reprojecting an Extent object in a Python Toolbox

LewisTrotter — Thu, 19 Dec 2024 03:34:11 GMT

Hello,

I am wondering how to reproject an arcpy.Extent object. I have a Python script toolboxes with a single GPExtent parameter. In the execute block, I have the following code:

ext = parameters[0].value srs = arcpy.SpatialReference(4326) ext.projectAs(srs)

When I run this, I get an error stating "RuntimeError: Object: CreateObject error creating spatial reference". Am I doing something wrong? Oddly, the above code runs fine in a notebook.

Thanks in advance!

Re: Reprojecting an Extent object in a Python Toolbox

DanPatterson — Thu, 19 Dec 2024 10:20:50 GMT

Extent—ArcGIS Pro | Documentation

What is parameter 0? use an AddMessage to report it. Perhaps the extent object is non-existent or not in the correct form

Re: Reprojecting an Extent object in a Python Toolbox

LewisTrotter — Fri, 20 Dec 2024 03:40:46 GMT

Thanks Dan,

It is an Extent object, I can pluck the XMin, XMax et al. from it no problem. It also appears to have the correct .spatialReference.

Re: Reprojecting an Extent object in a Python Toolbox

DanPatterson — Fri, 20 Dec 2024 04:25:08 GMT

You might want to have a look at this link

Python Extent Calculations

it uses the extent object to make a geometry object, project it, then get the extent... seems to contradict the projectAs in the help though if the source and destination spatial references are known and correct

Re: Reprojecting an Extent object in a Python Toolbox

HaydenWelch — Fri, 20 Dec 2024 14:20:45 GMT

You might need to assign a transformation, according to the docstring for Extent.projectAs():

If your projection requires a transformation, you can use ListTransformations to get a list of valid transformations and pass those to the call:

from arcpy import Extent, SpatialReference, ListTransformations ext: Extent = parameters[0].value srs = SpatialReference(4326) transformation: str = ListTransformations(ext.spatialReference, srs, extent=ext)[0] ext.projectAs(srs, transformation_name=transformation)

Re: Reprojecting an Extent object in a Python Toolbox

KristinBlier — Tue, 03 Jun 2025 16:03:58 GMT

Thanks! I ran into the same issue recently, and converting the extent to a geometry fixed it. Seems to be a python toolbox bug, because the Extent projectAs() works fine from a python shell. Never would've figured that out...