MongoDB lookup when foreign field is an array of objects

by

You can use below aggregation with mongodb 3.6 and above

db.resources.aggregate([
  { "$match": { "type": "FUNC" } },
  { "$lookup": {
    "from": "initiatives",
    "let": { "id": "$_id" },
    "pipeline": [
      { "$match": { "$expr": { "$in": ["$$id", "$ressources.function"] } } },
      { "$unwind": "$ressources" },
      { "$match": { "$expr": { "$eq": ["$ressources.function", "$$id"] } } },
      { "$group": {
        "_id": "$ressources.function",
        "participation_sum": { "$sum": "$ressources.participating" }
      }}
    ],
    "as": "result"
  }}
])

More Related Contents:

  1. Group result by 15 minutes time interval in MongoDb
  2. Get names of all keys in the collection
  3. How to filter array in subdocument with MongoDB [duplicate]
  4. MongoDB: Combine data from multiple collections into one..how?
  5. Moongoose aggregate $match does not match id’s
  6. Find in Double Nested Array MongoDB
  7. Multiple join conditions using the $lookup operator
  8. Conditional $sum in MongoDB
  9. Check if every element in array matches condition
  10. Get a count of total documents with MongoDB when using limit
  11. Include all existing fields and add new fields to document
  12. mongodb count num of distinct values per field/key
  13. exclude fields in $lookup aggregation
  14. MongoDB aggregation comparison: group(), $group and MapReduce
  15. Add some kind of row number to a mongodb aggregate command / pipeline
  16. MongoDB group by array inner-elements
  17. Multiple Counts with single query in mongodb
  18. MongoDB sort documents by array elements
  19. How to return array of string with mongodb aggregation
  20. How to return just the nested documents of an array from all documents
  21. Mongodb aggregation $group, restrict length of array
  22. Get n-th element of an array in MongoDB
  23. Geospatial $near within current document field value
  24. How do I rename fields when performing search/projection in MongoDB?
  25. Mongodb aggregation pipeline how to limit a group push
  26. mongodb aggregation framework match by nested documents
  27. count array occurrences across all documents with mongo
  28. $project in $lookup mongodb
  29. Mongodb concat int and string
  30. Return actual type of a field in MongoDB

Leave a Comment