Add To Set

The AddToSet method can be chained to a query to add a value to an array field in the documents that match the query but only if the value is not already in the array.

Usage

result := WitcherModel.Where("name", "Vesemir").AddToSet("weapons", "Crossbow", "Axe", "Dagger").Exec().(*mongo.UpdateResult)

In the example above, we are adding the values "Crossbow", "Axe", and "Dagger" to the weapons array of the witcher named Vesemir. If any of these values are already present in the array, they will not be added again.