$mergeObjects requires object inputs, but input is of type array

Question

I am trying to add one property if current user has permission or not based on email exists in array of objects.

My input data looks like below.

[
  {
    nId: 0,
    children0: [
      {
        nId: 3,
        access: [
          {
            permission: "view",
            email: "user1@email.com"
          }
        ]
      },
      {
        nId: 4,
        access: [
          {
            permission: "view",
            email: "user2@email.com"
          }
        ]
      }
    ]
  }
]

https://mongoplayground.net/p/xZmRGFharAb

[
  {
    "$addFields": {
      "children0": {
        "$map": {
          "input": "$children0.access",
          "as": "accessInfo",
          "in": {
            "$cond": [
              {
                "$eq": [
                  "$$accessInfo.email",
                  "user1@email.com"
                ]
              },
              {
                "$mergeObjects": [
                  "$$accessInfo",
                  {
                    "hasAccess": true
                  }
                ]
              },
              {
                "$mergeObjects": [
                  "$$accessInfo",
                  {
                    "hasAccess": false
                  }
                ]
              },
              
            ]
          }
        }
      }
    }
  }
]

I also tried this answer as following, but that is also not merging the object.

https://mongoplayground.net/p/VNXcDnXl_sZ

Answer 1

Try this:

db.collection.aggregate([
  {
    "$addFields": {
      "children0": {
        "$map": {
          "input": "$children0",
          "as": "accessInfo",
          "in": {
            nId: "$$accessInfo.nId",
            access: "$$accessInfo.access",
            hasAccess: {
              "$cond": {
                "if": {
                  "$ne": [
                    {
                      "$size": {
                        "$filter": {
                          "input": "$$accessInfo.access",
                          "as": "item",
                          "cond": {
                            "$eq": [
                              "$$item.email",
                              "user1@email.com"
                            ]
                          }
                        }
                      }
                    },
                    0
                  ]
                },
                "then": true,
                "else": false
              }
            }
          }
        }
      }
    }
  }
])

Here, we use one $map to loop over children0 and then we filter the access array to contain only elements with matching emails. If the filtered array is non-empty, we set hasAccess to true.

Playground link.