I want to define a list of values for a Parameter as all the values for a particular field in a Feature Class.
How do I do that?
I doubt you can define a parameter as values in a field. You can pass a shapefile and field as input parameter.
Refer this blog Create a list of unique field values | ArcPy Café , get a list of values in your script and loop through the values.
You should be able to use Tool Validation for this. Also, see here for a working example, employing an arcpy.da.SearchCursor.
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