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3

I am trying to create a tool from a python script I have written that will take a list I have created and use it as a drop-down menu in the finished tool as one of the inputs (see attached image for example):

enter image description here

The list I am using is a large list that includes all the towns in the state of Vermont, and I generate it in the script from a table (see code below). I suspect my problem at the moment is just with setting the tool Properties to take this list and use it to create a drop-down list for the user. Here is the block of code that creates the list for use in the parameter - does anybody see any problems with this code-end of the tool?

import arcpy
arcpy.env.workspace = "Z:\\OPS\\TechnicalServices\\Culverts\\GetCulverts\\GetCulverts.gdb"
towns = "Database Connections\\GDB_GEN.sde\\GDB_Gen.VTRANS_ADMIN.townindex"
arcpy.MakeFeatureLayer_management(towns,"towns_lyr")

NameList = []
NameListArray = set()
rows = arcpy.SearchCursor("towns_lyr")
for row in rows:
    value = row.getValue("TOWNNAME")
if value not in NameListArray:
    NameList.append(value)
town = NameList

town = arcpy.GetParameterAsText(0)

Here is an image of the Tool properties as well, with the default validation code - do I need to alter this validation code?

I looked for info on altering this validation code, but I could not find info on using it for formatting drop-down lists.

enter image description here

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1 Answer 1

up vote 4 down vote accepted

Try setting the tool validator class code to this:

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."""
    towns = "Database Connections\\GDB_GEN.sde\\GDB_Gen.VTRANS_ADMIN.townindex"
    rows = arcpy.SearchCursor(towns)
    self.params[0].filter.list = sorted(list(set(r.getValue('TOWNNAME') for r in rows)))
    del rows
    return

  def updateMessages(self):
    """Modify the messages created by internal validation for each tool
    parameter.  This method is called after internal validation."""
    return
share|improve this answer
    
Excellent! Thanks! That worked perfect. The next task I have, which may be more complicated, is to make the next user input do the same thing, but have it based on the choice in the first input - I will post a follow up to this question with those details soon. –  GISdan Sep 15 '14 at 16:23
1  
GISdan if it worked for you then you should tick @crmackey answer as correct. It's just not cricket if you don't... :( –  Hornbydd Sep 15 '14 at 17:28
    
Sorry, I was working on a follow up to crmackey's reply, but haven't finished testing it yet. I have now ticked the answer as correct. Thanks for the nudge. –  GISdan Sep 15 '14 at 19:23

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