Constructing the ToolValidator Class to Validate Inputs in a Python Script Tool containing Multiple Tools
Fundamentally confused. I made a Python Script Toolbox with multiple tools (hopefully proper terminology):
Each tool works fine, and the basic Python code/structure is as shown below. NOTE! I am only showing one of the Tools (metadata_mcm) and not update_attr or xml_element_csv_creator - but they are the same in basic structure. Skip to my questions below before diving into code.
class Toolbox(object):
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 = [metadata_mcm, create_xml_element_csv, update_attr]
class ToolValidator(object):
"""Class for validating a tool's parameter values and controlling
the behavior of the tool's dialog."""
def __init__(self):
"""Setup arcpy and the list of tool parameters."""
self.params = arcpy.GetParameterInfo()
def initializeParameters(self):
"""Refine the properties of a tool's parameters. This method is
called when the tool is opened."""
return
def updateParameters(self):
"""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):
"""Modify the messages created by internal validation for each tool
parameter. This method is called after internal validation."""
self.params[1].clearMessage()
if self.params[1].value is None:
self.params[1].clearMessage()
else:
if os.path.exists(self.params[1]):
self.params[1].setErrorMessage('output path already exists')
else:
self.params[1].clearMessage()
return
class create_xml_element_csv(object):
def __init__(self):
self.label = "xml element csv creator"
self.desciption = "create inventory of xml elements relevant to fields"
self.canRunInBackground = False
def getParameterInfo(self):
"""Define parameter definitions"""
param0 = arcpy.Parameter(
displayName="Input Feature",
name="fc_in",
datatype="Layer",
parameterType="Required",
direction="Input")
param1 = arcpy.Parameter(
displayName="Path/to/file.csv",
name="fp_csv",
datatype="DEFile",
parameterType="Required",
direction="Input")
params = []
params.append(param0)
params.append(param1)
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."""
def execute(self, parameters, messages):
"""The source code of the tool."""
fc = parameters[0]
desc = arcpy.Describe(fc)
fp_fc = desc.featureClass.catalogPath
fp_csv = parameters[1].valueAsText
st0, st1 = os.path.splitext(fp_csv)
# csv
if st1 == '.csv':
pass
else:
fp_csv = '{}.csv'.format(fp_csv)
flds = [f.name for f in arcpy.ListFields(fp_fc)]
vals = np.column_stack([flds, [None] * len(flds), [None] * len(flds), [None] * len(flds)])
# attrdef = definition
# attrdefs = definition source
cn = ['attrlabl', 'attralias', 'attrdef', 'attrdefs']
df_fields = pd.DataFrame(vals, columns=cn)
df_fields.to_csv(fp_csv)
return
I don't understand a couple things:
1) Can the ToolValidator Class work with multiple tools? It's odd that I have essentially hard-coded the paramaters positionally in updateMessages for ALL subsequent tools. I want to ensure that the output file does not exist prior to running tool. This is argument 1 for create_xml_element_csv but doesn't exist for the two other tools. So can I create a ToolValidator Class and only apply the validation to one tool in the toolbox?
2) Is my syntax within ToolValidator/updateMessages method correct? Found this syntax from a StackExchange response.
The tools run BUT the validation of
if os.path.exists(self.params[1]):
self.params[1].setErrorMessage('output path already exists')
is not being performed. I can pass an argument of a path that exists, and no warming is issued, tool overwrites the existing file. No bueno.
Thanks,
Zach
Tentatively found a solution. Any alternatives to the conditional logic: if parameters[1].value would be greatly appreciated! But it works. Code is commented to explain why I did this.
def updateMessages(self, parameters):
"""Modify the messages created by internal validation for each tool
parameter. This method is called after internal validation."""
# This if statement required or else error message will for parameter[0]
# "TypeError: stat: path should be string, bytes, os.PathLike or integer, not NoneType".
# Apparently this method will run through ALL parameters right off the bat. So add
# conditional statements to ensure validation only performed on target parameters i.e. parameter[1] in this case
if parameters[1].value:
fp_csv = parameters[1].valueAsText
if os.path.exists(fp_csv):
parameters[1].setErrorMessage('output path already exists')
else:
parameters[1].clearMessage()
returnNote that when an existing path/to/file.csv is passed for argument 2 (parameters[1]), the message will display:
Perhaps a new post is in order. Do either of you have experience defining an argument as a DETextFile or DEFile? For another Python Toolbox built on the same template you all helped me with (thanks!), I want to pass a path/to/csv as an argument. Spent the hour fleshing out, copying and pasting the .pyt. Looks good. Tool opens, but when I select (or try to select) the input csv in both the third and fourth arguments, it doesn't load - argument input box(es) stay blank. I've tried manually copying the path/to/file.csv into the argument, csv GIS attribute table in this case. Same thing.
When I try running the tool I, an error is thrown about NoneType as would be expected. My first instinct is to think an ESRI bug, but I'll withhold judgement until digging. Just trying to pass a file as an argument.
