DataWeave functions fail when moved to a module - module

Question

I'm having trouble moving functions to a custom Module file.
Using Anypoint Studio v7.11.1. I have this code that works in a Transform Message component:
%dw 2.0
output application/json
var flights = {
"flights": [
{
"airlineName": "Delta",
"availableSeats": 40,
"departureDate": "Apr 11, 2018",
"destination": "LAX",
"flightCode": "A134DS",
"origination": "MUA",
"planeType": "BOEING 777",
"price": "750.00"
},
{
"airlineName": "Delta",
"availableSeats": 18,
"departureDate": "Aug 11, 2018",
"destination": "LAX",
"flightCode": "A1QWER",
"origination": "MUA",
"planeType": "BOEING 747",
"price": "496.00"
},
{
"airlineName": "Delta",
"availableSeats": 10,
"departureDate": "Feb 11, 2018",
"destination": "LAX",
"flightCode": "A1B2C4",
"origination": "MUA",
"planeType": "BOEING 737",
"price": "199.99"
},
{
"flightCode": "rree0001",
"availableSeats": 0,
"destination": "LAX",
"planeType": "Boeing 787",
"price": 541.0,
"origination": "MUA",
"departureDate": "2016-01-20T00:00:00",
"airlineName": "american"
},
{
"flightCode": "ffee0192",
"availableSeats": 0,
"destination": "LAX",
"planeType": "Boeing 777",
"price": 300.0,
"origination": "MUA",
"departureDate": "2016-01-20T00:00:00",
"airlineName": "american"
},
{
"flightCode": "eefd4511",
"availableSeats": 100,
"destination": "LAX",
"planeType": "Boeing 777",
"price": 900.0,
"origination": "MUA",
"departureDate": "2016-01-15T00:00:00",
"airlineName": "american"
},
{
"airlineName": "United",
"availableSeats": 52,
"departureDate": "2015/02/11",
"destination": "LAX",
"flightCode": "ER45if",
"origination": "MUA",
"planeType": "Boeing 737",
"price": 345.99
},
{
"airlineName": "United",
"availableSeats": 12,
"departureDate": "2015/04/11",
"destination": "LAX",
"flightCode": "ER45jd",
"origination": "MUA",
"planeType": "Boeing 777",
"price": 346
},
{
"airlineName": "United",
"availableSeats": 0,
"departureDate": "2015/06/11",
"destination": "LAX",
"flightCode": "ER0945",
"origination": "MUA",
"planeType": "Boeing 707",
"price": 423
}
]
}
import dw::modules::FlightsLibSolution
var keysToDelete = ["openFlightsAirportId", "type", "source"]
//var flights = readUrl("classpath://examples/flightsToLAX.json")
var airportDetailsByIATA = readUrl("classpath://airportInfoTiny.csv", "application/csv") groupBy $.IATA
fun joinAirportDetailsV2(payload :Object, keysToDelete = [], groupedAirportDetails = []) =
flights:{(
payload.flights map ( (flight) -> flight:
//join in the destination airport details with mapObject
flight mapObject (value, key, index) ->
if( lower(key) ~= "destination")
destination: groupedAirportDetails[ flight.destination ][0]
-- keysToDelete
//{(
//airportDetails[ ?($.IATA == flight.destination)]
//groupedAirportDetails[ flight.destination ]
//)}
else (key): value
)
)}
---
joinAirportDetailsV2(flights, keysToDelete, airportDetailsByIATA )
But when I move the function to the dw.modules.FlightsLibSolution.dwl file and I call
---
dw::modules::FlightsLibSolution::joinAirportDetailsV2(flights, keysToDelete, airportDetailsByIATA )
I get the error:
"Too many arguments (3) for function with parameters (payload, keysToDelete).
128| dw::modules::FlightsLibSolution::joinAirportDetailsV2(flights, keysToDelete, airportDetailsByIATA )
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
But if I call this function instead in a module
fun joinAirportDetailsV1(payload :Object,keysToDelete = [], groupedAirportDetails = []) =
flights:
{(
payload.flights map ( (flight) ->
flight:
flight - "destination"
//join in the destination airport details with ++
++ destination:
//{(
groupedAirportDetails[ flight.destination ][0]
//)}
//- "openFlightsAirportId" - "type" - "source"
-- keysToDelete
)
)}
It works.
Also, if I put this function in the Module:
fun joinAirportDetailsV3(payload :Object ) =
flights:{(
payload.flights map ( (flight) -> flight:
//join in the destination airport details with mapObject
flight mapObject (value, key, index) ->
if( lower(key) ~= "destination")
destination: groupedAirportDetails[ flight.destination ][0]
-- keysToDelete
//{(
//airportDetails[ ?($.IATA == flight.destination)]
//groupedAirportDetails[ flight.destination ]
//)}
else (key): value
)
)}
and then I define the two variables used in the function in my Transform Message component:
import dw::modules::FlightsLibSolution
var keysToDelete = ["openFlightsAirportId", "type", "source"]
var airportDetailsByIATA = readUrl("classpath://airportInfoTiny.csv", "application/csv") groupBy $.IATA
var groupedAirportDetails = airportDetailsByIATA
var flights = ...
---
FlightsLibSolution::joinAirportDetailsV3(flights)
I get the error:
output application/json
var flights = {
"flights": [
{
...'. Reason: Unable to resolve reference of: `groupedAirportDetails`.```
Why isn't the `groupedAirportDetails` variable resolved? This is not just a Preview pane error. I get the same error raised then I run the Mule app.

Answer 1

The syntax to import a functions is:
import joinAirportDetailsV3 from dw::modules::FlightsLibSolution
For that to work there has to be file named FlightLibSolution.dwl in the src/main/resources/dw/modules directory.
Alternatively, you can import all functions from the module like this:
import * from dw::modules::FlightLibSolution