OrientDB ETL: how to skip a duplicate vertex but create the edge - orientdb

Question

I am creating a communication graph.
Each message has a msgid and each person has a userid.
I have already created the message vertices, now i want to create the user vertices and an edge connecting a message vertex to the user vertex.
A user can get multiple messages (obviously).
My file contains:
msgid, userid, (and some other info i will assign to the edge)
The isssue that i am having is that in my file i have duplicate userids (because users can get multiple messages), i dont want to create another vertex with the user id so i skipDuplicates. But if i do skip duplicates the edge will not get created either. I do want multiple edges to the same user vertex as each edge represents one message.
How do i keep the User vertex unique but create the edge?
My current ETL .json file that works fine with the exception of what i have detailed above.
{
"source": { "file": { "path": "msgs.txt" } },
"extractor": { "row": {} },
"transformers": [
{ "csv": {"separator": "\t"} },
{ "vertex": { "class": "user", "skipDuplicates": true } },
{ "edge": { "class": "sent_to", "joinFieldName": "msgid", "lookup":"message.id","direction": "in" } },
"edgeFields": { "n": "${input.n}" }
],
"loader": {
"orientdb": {
"dbURL": "remote:/localhost/databases/communication",
"dbType": "graph",
"classes": [
{"name": "user", "extends": "V"},
{"name": "message", "extends": "V"},
{"name": "sent_to", "extends": "E"}
], "indexes": [
{"class":"user", "fields":["id"], "type":"UNIQUE" }
]
}
}
}

Answer 1

Okay, here is what i did and it seemed to work.
First i created the message vertices (as stated above, in the q.).
Then i created the user vertices.
Then to create the edge in between them i ran the following ETL on a file that had {userid, msgid, ...}
{
"source": { "file": { "path": "msgs1.txt" } },
"extractor": { "row": {} },
"transformers": [
{ "csv": {"separator": "\t"} },
{ "merge": {"joinFieldName": "userid", "lookup": "user.id"} },
{ "vertex": { "class": "user", "skipDuplicates": true } },
{ "edge": { "class": "sent_to",
"joinFieldName": "msgid",
"lookup":"message.id",
"direction": "in",
"edgeFields": { "n": "${input.n}", "date": "${input.date}"}
}
}
],
"loader": {
"orientdb": {
"dbURL": "remote:/localhost/databases/communication",
"dbType": "graph",
"classes": [
{"name": "user", "extends": "V"},
{"name": "message", "extends": "V"},
{"name": "sent_to", "extends": "E"}
],
"indexes": [
]
}
}
}
This created all the edges, even if there was more than one edge pointing to a user.
Hopefully this will help someone