Creating a ValueTable with a column that has dependency

Question

I am creating a python tool which looks like the figure below.

Input feature: It asks for a input feature class. Valuetable(Lookup tables): It has two columns - one for look up tables and another for fields.

The fields in value table should have dependency on Input feature. is this possible ? How ?

Code:

 def getParameterInfo(self):
    param1 = arcpy.Parameter(
        displayName = "Input Feature",
        name = "in_features",
        datatype = "DEFeatureClass",
        parameterType = "Required",
        direction= "Input")
    param1.filter.list = ["Polyline"]

    param2 = arcpy.Parameter(
        displayName='Lookup tables',
        name='lookup',
        datatype='GPValueTable',
        parameterType='Required',
        direction='Input')

    param2.columns = [ ['DETable', 'LookupTable'], ['Field', 'Fields']]


    param2.filters[1].type="ValueList"  
    desc = arcpy.Describe(param1)  
    fields = desc.fields
    l=[]
    for f in fields:
        l.append(f.name)
    param2.filters[1].list = l

    param3 = arcpy.Parameter(
        displayName='Output',
        name='excel',
        datatype='DEFile',
        parameterType='Required',
        direction='Output')
    param3.filter.list = ['xls', 'xlsx']



    params = [param1, param2, param3]
    return params

Answer 1

I think you need to have the Fields as the first column in the Value Table in order to use the parameter dependency:

import arcpy
import pythonaddins

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 = ""

        # List of tool classes associated with this toolbox
        self.tools = [SomeTool]

class SomeTool(object):
    def __init__(self):
        """Define the tool (tool name is the name of the class)."""
        self.label = "Set up Variables"
        self.description = ""
        self.canRunInBackground = False

    def getParameterInfo(self):
        param1 = arcpy.Parameter(
            displayName = "Input Feature",
            name = "in_features",
            datatype = "DEFeatureClass",
            parameterType = "Required",
            direction= "Input")
        param1.filter.list = ["Polyline"]

        param2 = arcpy.Parameter(
            displayName='Lookup tables',
            name='lookup',
            datatype='GPValueTable',
            parameterType='Required',
            direction='Input')

        param2.columns = [ ['Field', 'Fields'], ['DETable', 'LookupTable']]


        param3 = arcpy.Parameter(
            displayName='Output',
            name='excel',
            datatype='DEFile',
            parameterType='Required',
            direction='Output')
        param3.filter.list = ['xls', 'xlsx']
        param2.parameterDependencies = [param1.name]

        params = [param1, param2, param3]
        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('Success')   
        return