Filtering layers that show for input feature layer parameter for custom tool?

Question

When creating a custom tool using a Python script, is there a way to only show layers that, for example, contain a certain word?

For the drop down of the input polygon feature, I only want layers to show that have the word boundary in them.

Is this possible, or does it just automatically show all layers in the document?

Here's a screenshot of what I'm talking about:

It's a bad example because it only shows one layer, but image lots, and lots of layers.

Answer 1

You need to use tool validation for this. For custom Python script tool (that has two input parameters - string with filter value list and string with filter value list for feature layers in the currently open map document).

import arcpy
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."""
    if self.params[0].value:
        upd_list = []
        mxd = arcpy.mapping.MapDocument(r"CURRENT")
        df = arcpy.mapping.ListDataFrames(mxd, "Layers")[0]
        for lyr in arcpy.mapping.ListLayers(mxd, "*{0}*".format(self.params[0].value), df):
            upd_list.append(lyr.name)
        self.params[1].filter.list = upd_list    
    return

  def updateMessages(self):
    """Modify the messages created by internal validation for each tool
    parameter.  This method is called after internal validation."""
    return

For Python toolbox tool:

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

    def getParameterInfo(self):
        """Define parameter definitions"""
        in_filter = arcpy.Parameter(
            displayName="Input filter word",
            name="in_filter",
            datatype="GPString",
            parameterType="Required",
            direction="Input")
        in_filter.filter.type = "ValueList"
        in_filter.filter.list = ["Boundary","Border"]

        in_fc = arcpy.Parameter(
            displayName="Input Features",
            name="in_features",
            datatype="GPString",
            parameterType="Optional",
            direction="Input")
        in_fc.filter.type = "ValueList"
        in_fc.filter.list = []

        parameters = [in_filter,in_fc]
        return parameters

    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].value:
            upd_list = []
            mxd = arcpy.mapping.MapDocument(r"CURRENT")
            df = arcpy.mapping.ListDataFrames(mxd, "Layers")[0]
            for lyr in arcpy.mapping.ListLayers(mxd, "*{0}*".format(parameters[0].value), df):
                upd_list.append(lyr.name)
            parameters[1].filter.list = upd_list
        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."""
        return