如何在mongoDB版本3.6中查找字符串和$ Objcectid。如果在4.0版本中有$ toObjectId,那么版本3.6中有类似的东西吗?
{ $toObjectId: <expression> }到{ $convert: { input: <expression>, to: "objectId" } }
{ $toObjectId: <expression> }
{ $convert: { input: <expression>, to: "objectId" } }