I have a questions collection with _id and name and other fields(..), and a tests collection with _id, name and array of questions.
I'm trying to get all the questions with their fields and adding a field "usedIn" which counts the number of tests that the specific questions is present in.
questions = await Question.aggregate([ /*{ "$match": { params } },*/ { "$lookup": { "from": "tests", "let": {"questionId": "$_id"}, pipeline: [ { "$match": { "$expr": { "$in": ["$$questionId", "$questions"], }, }, }, ], as: "tests" } }, { "$addFields": { "usedIn": { "$size": "tests" } } }, { "$project": fieldsObject }, ]) This code is giving me this error:
Error: Failed to optimize pipeline :: caused by :: The argument to $size must be an array, but was of type: string
What Am I doing wrong ?
