Using Python Toolbox Parameters

Question

I want to specify an input for each column of the 'field compare' parameter, so it would be 'baseFeatures' would link just to the 'Base Fields' column and 'updatedFeatures' would just link to the 'Updated Fields' column. This is basically what 'Compare Fields' do in the 'Detect Feature Changes' tool.

This is what I did.

class Tool(object):
def __init__(self):
    """Define the tool (tool name is the name of the class)."""
    self.label = "Compare Features"
    self.description = "Compare the features from two datasets (a base one and an updated one)" + \
                       "and returns the desired outputs."
    self.canRunInBackground = False

def getParameterInfo(self):
    """Define parameter definitions"""
    baseFeatures = arcpy.Parameter(displayName="Input Base Features", name="base_Features", datatype="GPFeatureLayer", parameterType="Required", direction="Input")

    updatedFeatures = arcpy.Parameter(displayName="Input Updated Features", name="updated_Features", datatype="GPFeatureLayer", parameterType="Required", direction="Input")

    linearUnit = arcpy.Parameter(displayName="Search Distance", name="search_distance", datatype="GPLinearUnit", parameterType="Required", direction="Input")

    fieldCompare = arcpy.Parameter(displayName="Compare Fields", name="compareFields", datatype="GPValueTable", parameterType="Optional", direction="Input")
    paramNames = [baseFeatures.name, updatedFeatures.name]
    fieldCompare.parameterDependencies = paramNames
    fieldCompare.columns = [['Field', 'Base Fields'], ['Field', 'Updated Fields']]

    geometryOutput = arcpy.Parameter(displayName="Geometry Changes Output", name="newandnochange_Features", datatype="GPBoolean", parameterType="Optional", direction="Input")

    attributeChangeOutput = arcpy.Parameter(displayName="Attribute Changes Output", name="attributechanges_Features", datatype="GPBoolean", parameterType="Optional", direction="Input")

    delAndNewOutput = arcpy.Parameter(displayName="Deleted/New Features", name="delandnew_Features", datatype="GPBoolean", parameterType="Optional", direction="Input")

    params = [baseFeatures, updatedFeatures, linearUnit, fieldCompare, geometryOutput, attributeChangeOutput ,delAndNewOutput]

    return params

I thought that with parameter dependencies I could specify two names, instead it only takes into account the first name I choose in the dependencies list (if Ihave 'baseFeatures.name' first both columns will only have the baseFeatures columns / if I have 'updatedFeatures.name' first it will only have the updatedFeature columns), and I can't "link" one parameter with the desired cloumn.

Does anyone know what am I missing?

Answer 1

This is the expected behaviour, which is similar to Dissolve or Summary Statistics tools. You can set one dependency to the extract fields of a table (i.e., feature class as well). If you change fieldCompare.parameterDependencies = paramNames to fieldCompare.parameterDependencies = [baseFeatures.name] presuming you want to list base data's fields to compare and set your columns as fieldCompare.columns = [['Field', 'Base Fields'], ['String', 'Updated Fields']], you will have the correct initial setup.

Following that you need to control Updated Fields from def updateParameters(self, parameters): by checking the state of updatedFeatures variable. This question may help: Updating ValueTable parameter of ArcPy Python Toolbox tool.

UPDATE

The ESRI Community answer that you posted devises a similar approach, removing dependencies, and populating the fields of base... and updated... table fields when layer selections are made for all. However, it may fail if you change your layer selected. I suggest similar approach which might solve this issue as keeping the dependency.

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."""
    if parameters[1].altered and not parameters[1].hasBeenValidated:
        # Reset the corresponding update field when the "updated..." selection is changed, 
        # if there is existing field(s) in the value table
        if parameters[3].values:                
            parameters[3].values = [[i[0].value, ''] for i in parameters[3].values]
        # Populate the updated side of the value table with the fields from the "updated..."
        parameters[3].filters[1].list = [f.name for f in arcpy.ListFields(parameters[1].value)]
    return 

Answer 2

I got a response from the ESRI community that solved the problem.

This is the code:

def getParameterInfo(self):
    """Define parameter definitions"""
    baseFeatures = arcpy.Parameter(displayName="Input Base Features", name="base_Features", datatype="GPFeatureLayer", parameterType="Required", direction="Input")
    updatedFeatures = arcpy.Parameter(displayName="Input Updated Features", name="updated_Features", datatype="GPFeatureLayer", parameterType="Required", direction="Input")
    linearUnit = arcpy.Parameter(displayName="Search Distance", name="search_distance", datatype="GPLinearUnit", parameterType="Required", direction="Input")
    fieldCompare = arcpy.Parameter(displayName="Compare Fields", name="compareFields", datatype="GPValueTable", parameterType="Optional", direction="Input")
    fieldCompare.columns = [['GPString', 'Base Fields'], ['GPString', 'Updated Fields']]
    geometryOutput = arcpy.Parameter(displayName="Geometry Changes Output", name="newandnochange_Features", datatype="GPBoolean", parameterType="Optional", direction="Input")
    attributeChangeOutput = arcpy.Parameter(displayName="Attribute Changes Output", name="attributechanges_Features", datatype="GPBoolean", parameterType="Optional", direction="Input")
    delAndNewOutput = arcpy.Parameter(displayName="Deleted/New Features", name="delandnew_Features", datatype="GPBoolean", parameterType="Optional", direction="Input")
    params = [baseFeatures, updatedFeatures, linearUnit, fieldCompare, geometryOutput, attributeChangeOutput ,delAndNewOutput]

    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."""
    if parameters[0].valueAsText and parameters[1].valueAsText:
        desc_b = arcpy.Describe(parameters[0].value)
        desc_u = arcpy.Describe(parameters[1].value)
        parameters[3].filters[0].list = [field.name for field in desc_b.fields]
        parameters[3].filters[1].list = [field.name for field in desc_u.fields]

    return

I will now finish this question.