I want to perform a selection on tool startup in order to obtain a choice list for parameter derived from selected features. Code kind of works, as I get my choice list with correct values, however it works in a strange way:
- After pasting code into validation window and clicking OK, selection starts and is performed several times.
- On the first tool startup, selection is done again several times.
- Choice list gets remembered as Value List and doesn't change with further tool startups (in fact on next startups, nothing new happens - no selection or any other actions from initializeParameters).
What am I doing wrong?
Here is a code:
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.""" arcpy.SelectLayerByLocation_management(in_layer="OBR", overlap_type="CONTAINS", select_features="POW") choice_list =  with arcpy.da.SearchCursor("OBR", ["OBR", "NAZWA"]) as cursor: for row in cursor: choice_list.append(row) arcpy.SelectLayerByAttribute_management("OBR", "CLEAR_SELECTION") self.params.filter.list = choice_list 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.""" return def updateMessages(self): """Modify the messages created by internal validation for each tool parameter. This method is called after internal validation.""" return