Embed operator $exists within the operator $map-CodePudding

I am extending the solution provided at this example where I am adding multiple conditions within the "in" of operator $map. All the conditions need to be true so I'm using $and operator to combine them. The new condition checks whether a particular field exists as a key in the document. I am using operator $exists to check this. The code snippet to check this condition is

{
 "isTypePattern": {
    $exists: false
  }
}

where the name of the field (to check for existence) is: isTypePattern. This snippet works independently however when embedded under $map operator it throws a compile error:

The code looks like following and here is the playground link:

db.collection.find({
  "$expr": {
    "$anyElementTrue": {
      "$map": {
        "input": "$entities",
        "in": {
          $and: [
            {
              "$regexMatch": {
                "input": "Room1",
                "regex": "$$this.id",
                "options": "i"
              },
              
            },
            {
              "isTypePattern": {
                $exists: false
              }
            }
          ]
        }
      }
    }
  }
})

So if someone can suggest how to embed $exists within $map operator that would be great

CodePudding user response：

Maybe something like this:

db.collection.find({
"$expr": {
"$anyElementTrue": {
  "$map": {
    "input": "$entities",
    "in": {
      $and: [
        {
          "$regexMatch": {
            "input": "Room1",
            "regex": "$$this.id",
            "options": "i"
          },
          
        },
        {
          $eq: [
            {
              $type: "$$this.isTypePattern"
            },
            "missing"
          ]
        }
      ]
    }
   }
  }
 }
})

Explained:

$expr allow using $type and aggregation comparison operators like $eq,$ne,$lt,$gt that can be used for the case , but do not support $exists.

playground