Hi @Willy - thanks for the example - that was helpful!
Try changing the filter to this:
return {
"isExternalFilterPresent": {"function": "true"},
"doesExternalFilterPass": {"function": f"params.data.City === '{city}' && params.data.State === '{state}' && params.data.Population === {population}"}
}
Just need to use the correct field name and data type. Your version was using a string for the population.