[GIS] How to fill Field Mappings parameter in script tool on updateParameters

arcpyfield-mappingparameterspython-script-tooltool-validation

My goal is to get a list of fields choosen by an user from existing fields in feature class.
I think that I can show all fields in Field Mappings dialog, an user deletes unwanted fields and I get a required list.

The problem is how to populate Field Mappings when adding a feature class as a first parameter.
I can't select anything in 'Obtained from' property.
The code self.params[1].parameterDependencies = [0] in updateParameters function does't work in this case (it worked when 'Field' parameter data type was chosen).

What should I use to automatically populate Field Mappings when filling first parameter?

EDIT:
Fields list is applied as follows:
enter image description here

Best Answer

Under your Fields to Choose option, change it to Field instead of Field Mappings. That will give you a list of the feature layer fields.

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You're not really supposed to do this, but you could open a cursor in your validator's updateParameters method.

if self.params[0].value and arcpy.Exists(self.params[0].value):
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This will take some feature layer/table from the first parameter and populate the second parameter's dropdown with a list of values in its COL_NAME field.

Note: this will greatly slow down your validator and is highly discouraged.

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