MongoDB update document property array of strings $push if not present $pull if present

Question

DATA = [
  {
    name: 'one',
    example: {
      arrayOfStrings: ['one', 'two', 'three']
    }
  }
]

db.getCollection('test').update(
  {name: 'one'},
  [
    {
      // From access.roles, if value is not there, then add it to array of strings.
      // if it is there, remove it from the array of strings.
    }
  ]
)

Something like below, but working.

{
  $cond: [
    {
      $in: ['one', '$example.arrayOfStrings']
    },
    {$pull: {'$example.arrayOfStrings': 'one'}},
    {$push: {'$example.arrayOfStrings': 'one'}},
  ]
}

Answer 1

When "one" does exist in the example.arrayOfStrings array, use the $filter operator to remove it from the array.

Otherwise, use the $concatArrays operator by providing "one" in an array to perform adding the element to the array.

db.collection.update({
  name: "one"
},
[
  {
    $set: {
      "example.arrayOfStrings": {
        $cond: [
          {
            $in: [
              "one",
              "$example.arrayOfStrings"
            ]
          },
          {
            $filter: {
              input: "$example.arrayOfStrings",
              cond: {
                $ne: [
                  "$$this",
                  "one"
                ]
              }
            }
          },
          {
            $concatArrays: [
              "$example.arrayOfStrings",
              [
                "one"
              ]
            ]
          }
        ]
      }
    }
  }
])

Demo @ Mongo Playground