(Python 3.6) call a variable from a python toolbox file (.pyt)

Question

Hello everyone! I'd really appreciate it if someone could help me with this issue.

I have a customized python toolbox file (.pyt) and what I need to do is, from another module (.py), call a variable stored inside a function in that toolbox. Here's a quick overview of the .pyt file:

Validation.pyt

>class Validation(object):

>> def getParameterInfo(self):

>> def execute(self, parameters, messages):

>>> def check_geometry_poly(inputfile):

(...some code) error_count = x

I need to get the result from that error_count variable to use it in another script. I'm struggling with the fact that .pyt file doesn't seem to be callable like a normal .py module, where I would simply import Validation and call Validation.check_geometry_poly() to access the variable result.

Any ideas?

Thank you in advance!

C Castro

LongDinh · Accepted Answer

Hi @CCastro_GIS,

You can load a pyt file as a module by using the importlib.machinery.SourceFileLoader() method. SourceFileLoader allows you to create a module-like object from a text file which can then be imported in your script.

So it would look something like:

# Lets load MyToolBox.pyt from Z:\MyToolBox.pyt

import importlib
import os

pytDir = r"Z:"
pytFile = "MyToolBox.pyt"
pytPath = os.path.join(pytDir, pytFile)

# Create module-like object
pytModule = importlibe.machinery.SourceFileLoad(
   "MyToolBox", pytPath 
)
# Import the file as a module called MyToolbox (similar to a 'import MyToolbox' statement)
MyToolBox = pytModule.load_module("MyToolBox")

# Access the module and print some of its class/methods
print (MyToolBox)
print (MyToolBox.Validation().check_geometry_poly)

LongDinh · Accepted Answer

Hi @CCastro_GIS ,

You can use Python's Built-in vars() function or the Python Class object's Built-in __dict__ variable. Both return a dictionary/mapping object of all the stored attributes of the object.

If your object's variables are hard-coded into the Class object, the values will appear.

If they are stored via the arcpy.GetParameter within the class method, I suspect the attribute will not appear as it is encapsulated within the class method. You can probably assign the parameter to the class's self to make it appear after executing the method (ArcGIS Tool).

Something like the below should cover both scenarios (printing the stored variable in your Tool and printing the input parameter stored as a variable in your class at method call).

class MyToolBox(ToolBox):
 def __init__(self):
    # Use the ArcGIS ToolBox Template (I can't remember how it goes...)
    self.tools = [MyTool]

class MyTool(Tool):
 def __init__(self):
    self.stored_variable_to_print = 'Hello world'

def paramaters(self):
    self.dynamic_parameter = arcpy.Parameter("dynamicParameter" ...)
    self.parameters = [self.dynamic_parameter]
 def getParameters(self):
    # ...
    return self.parameters

def executeMyTool(self):
    print (self.__dict__)
    self._executeMyTool_dynamic = arcpy.GetParameter(0)
    # See if self.parameters[0] has changed to the set value, 
    # and check _executeMyTool_dynamic variable
    print (self.__dict__)
    return

print (vars(MyTool))