If you are trying to create a parameter filter based on a selection, you should do that within the Validation class. It executes python commands just like the execution block so you can dynamically create filters from other data. I don't think the internal wiring allows for modifying just the filter of a parameter outside of the Validation class.
Make my_content a parameter pointing to your data by default (used param[0] for the example and then build your list from there:
def updateParameters(self):
# get the list values
if self.params[1].value == 'dashboard':
fcFilter = self.params[1].filter
# use list comprehension and set to return a distinct list of values.
attributevalues = list(
set([cnt.title for cnt in self.params[0].valueAsText])) # parameter set to what the my_content variable is.
# sort alphabetically
attributevalues.sort()
# set the parameter list
fcFilter.list = attributevalues
If you must do it in through the execution (script), you may have to override/extend the Script Tool/ toolbox / Validation class to create the class methods to set values, or you can try by using SetParameterAsText and some dummy parameters.
It would be (using the next parameter index that is available):
L = ['a','b','c']
arcpy.SetParameterAsText(5, L)
Then do some parsing in the Validation class when the parameter is modified to make it into a list since you can only pass Objects or Text. I am not sure if the disabled boolean will also disable accessing/setting other properties. This is untested:
def initializeParameters(self):
# disable the dummy param to hide it from the UI
self.params[5].enabled = False
return
def updateParameters(self):
# Modify parameter values and properties.
# This gets called each time a parameter is modified, before
# standard validation.
if self.params[1].altered:
if self.params[1].value == 'dashboard':
if isinstance(self.params[5].value, str):
self.params[1].filterlist = self.params[5].value.strip('][').split(', ')
return
You'll have to play around with it.
