Mulitvalue string parameter with drop-down list in Python Script Tool

Discussion created by amilt on Mar 31, 2013
Latest reply on Apr 1, 2013 by amilt
I am trying to build a script tool using ArcGIS's 10.0 built-in python functionality. I have been trying to create a multiple value string parameter with a pre-determined set of values that each of the multiple values can take. For instance, I might give the user a value list including ['up', 'down', 'left', 'right'] and then in the tool dialog the user should be able to choose from that list multiple times, with repeats. For instance, the user might choose ['up', 'up', 'left'] as three separate inputs.

I cannot seem to get this to work. I do not want what ArcGIS considers a "MultiValue" "String" with a "Value List" filter. This only allows the user to select multiple values in the value list, without repeats.

Alternatively, I cannot get a satisfactory result when I create a "MultiValue" "String" with no filter. In this case, the user is completely unable to add to or remove values from the list (because, for some reason, the "Add Value" button is always disabled). How does that make any sense?

A third option, which I consider a huge failure if I have to resort to it, is to create two parameters, where the first parameter is a non-multivalue dropdown list and the second parameter is a multi-value string that successively appends choices from the first parameter to its values.

Is there a simple way to achieve what I am asking?