We make each parameter available because hard coded parameters can kill your tool 2% of the time. Or maybe more like 10%.... Whatever.
Its best to have all the parameters exposed in the tool dialog and loaded with the defaults your going to use 98% of the time. If these defaults are the same across many tools you don't want to be going into each tool's parameters to set the defaults. You want one location to set all the defaults. That's your config file bro.
So here is an example of one tool's tool validator that loads the defaults from a config file located in the same directory as the toolbox we are running the tool from.
import sys
import os
import ConfigParser
import arcpy
# Finds the path of the toolbox
scriptPath = sys.path[0]
# The config file should be in the same directory as the toolbox
configFile = scriptPath + "\\amp_config.cfg"
class ToolValidator:
"""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()
#Group the following parameters in the dialog box
self.params[2].category = "Defaults"
self.params[3].category = "Defaults"
self.params[4].category = "Defaults"
self.params[5].category = "Defaults"
self.params[6].category = "Defaults"
self.params[7].category = "Defaults"
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 parmater
has been changed."""
# If the config file is not found the parameters remain blank.
if not os.path.exists(configFile):
self.params[2].value = ""
self.params[3].value = ""
self.params[4].value = ""
self.params[5].value = ""
self.params[6].value = ""
self.params[7].value = ""
return
#If the config file is found it moves on to populate the parameters.
# Adds defalut values from the config file when the first paramter is filled for the first time.
if self.params[0].altered and not self.params[0].hasBeenValidated:
if not self.params[0].value == None:
# Loads the config file into memory
config = ConfigParser.SafeConfigParser()
config.readfp(open(configFile))
# Gets the values from the config file.
scratchDir = config.get('environment','scratchDir')
coverageName = os.path.basename(str(self.params[0].value))
logFile = scratchDir + "\\" + coverageName + "_log.txt"
self.params[3].value = logFile
self.params[4].value = coverageName
self.params[6].value = scratchDir + "\\" + coverageName + "_cov.gdb"
self.params[2].value = scratchDir
self.params[5].value = config.get('dataConversion','coverageList')
self.params[7].value = config.get('dataConversion','annotationLayerList')
# If parameter 1 is false then parameter 7 is greyed out.
if self.params[1].value == False:
self.params[7].enabled = False
else:
self.params[7].enabled = True
return
def updateMessages(self):
"""Modify the messages created by internal validation for each tool
parameter. This method is called after internal validation."""
return
