Update aggregate pipeline is updating array even i am tryign to give condition

[Shyam_Sohane]

I am trying to update the memberOfGroups array only if none of the element has the matching value. not sure why its taking even the condition is not satisfy, I can not give condition in find and use positional because I need to update more array inside document. so I need to utilize aggregation pipeline.
I can not use addtoset as there may be few field which are different , i can rely only on unique id.

Please try here.

Mongo playground

[turivishal (Vishal Turi)]

Hello @Shyam_Sohane,

I would suggest you use a normal query instead of update with aggregation pipeline, here is a query,

• check query if memberOfGroups._id is not present
• $push to add element in memberOfGroups array

db.principals.update(
  { 
    _id: "67448af8-a68b-4d08-8948-2cddca57d708",
    "memberOfGroups._id": {
      $ne: "ba93384d-d18a-4b36-9a24-7d3ebb1619d8"
    }
  },
  {
    $push: {
      memberOfGroups: {
        _id: "ba93384d-d18a-4b36-9a24-7d3ebb1619d8",
        name: "test group"
      }
    }
  }
)

Playground

---

Fixed issues in your query,

• Condition should check array by $in operator because $memberOfGroups._id returns an array of _ids
• True part return the current existing value of $memberOfGroups
• False part return concat array

db.principals.update(
  { _id: "67448af8-a68b-4d08-8948-2cddca57d708" },
  [{
    $set: {
      memberOfGroups: { $ifNull: ["$memberOfGroups", []] }
    }
  },
  {
    $set: {
      memberOfGroups: {
        $cond: [
          { $in: ["ba93384d-d18a-4b36-9a24-7d3ebb1619d8", "$memberOfGroups._id"] },
          "$memberOfGroups",
          {
            $concatArrays: [
              "$memberOfGroups",
              [
                {
                  _id: "ba93384d-d18a-4b36-9a24-7d3ebb1619d8",
                  name: "test group"
                }
              ]
            ]
          }
        ]
      }
    }
  }
])

Playground

[Shyam_Sohane]

Awesome, thanks Vishal. I was comparing opposite. Thanks.