Merge two JSON outputs into one with Dataweave - mule

Question

I currently have two JSON files with data.
The first has a list of actions by a user. However, the userID is a UID string instead of their user name.
The second is a JSON list of UID strings with their corresponding user names. I stored this JSON in a Flow Variable named UserPayload
I'd like to merge the user name into the first list so that my output has actual users names instead of the UID.
Here is what I had so far...but the userId part doesn't work since my flowVar is an list.
%dw 1.0
%output application/csv
---
payload map ((payload01, indexOfPayload01) -> {
user: payload.01.userId,
actions: payload01.action,
FileName: payload01.payload.properties.name default "N/A",
userId: flowVars.UserPayload.objectName
})
Any help would be appreciated. Thanks!

Answer 1

you can access the right object from the UserPayload flowVar by either filtering the content of UserPayload based on userId or creating a associative array from UserPayload.
filtering UserPayload
%dw 1.0
%output application/json
---
payload map (action, index) -> {
user: action.user,
action: action.action,
FileName: action.FileName,
userId: (flowVars.UserPayload filter $.objectId == action.user)[0].objectName
}
associative array
%dw 1.0
%output application/json
%var users = flowVars.UserPayload groupBy $.objectId
---
payload map (action, index) -> {
user: action.user,
action: action.action,
FileName: action.FileName,
userId: users[action.user][0].objectName
}
for my examples i used following sample data derived from your question.
flowVars.UserPayload
[{
"objectId": "0000-0000-0001",
"objectName": "first user"
}, {
"objectId": "0000-0000-0002",
"objectName": "second user"
}]
payload
[{
"user": "0000-0000-0001",
"action": "some crazy action",
"FileName": "some-crazy-action.mov"
}]