mongodb - Mongo Query for document existence in two collections

Question

I am new to Mongo and need to write a query which will perform the following steps:

1. Read collection "STAGING" and get all documents where "state" = "COMPLETE"
2. For each record found in step (1), check second collection "PROCESS" for its existence
3. If document exists in "PROCESS", do nothing. If document does not exist, insert a document.

I've tried to script the query up, but I'm hitting a wall. Here is my attempt so far:-

db.staging.find({"state":"COMPLETE"}).forEach(
   stagingDoc => {
      if (null !== db.process.find({ "jobReference": stagingDoc.jobReference }).forEach(
         record => {
            db.process.insertOne({
              "createdOn": new  Date(),
              "retryCount": 0,
              "jobReference": record.jobReference, 
              ...
            })
         }
       ))

question from:https://stackoverflow.com/questions/65941322/mongo-query-for-document-existence-in-two-collections

Answer 1

Waitting for answers