“MongoDB ist null” Code-Antworten

MongoDB ist null

/*
The first non-null input expression value found.
A replacement expression value if all input expressions evaluate to null.
*/

db.inventory.aggregate(
   [
      {
         $project: {
            item: 1,
            description: { $ifNull: [ "$description", "Unspecified" ] }
         }
      }
   ]
)