MongoKitten：检查 ObjectId 是否存在

Question

如何判断集合中是否存在ObjectId？我从 mongo 控制台执行此操作：

> db.collection.find({_id: ObjectId("5bb216a8475fe42644993a40")}, {_id: 1}).limit(1);

如何使用 MongoKitten 做同样的事情？

Answer 1

let mongoClient = try MongoKitten.Database("mongodb://\(username):\(password)@\(ipAddress)/\(database)")
let myCollection = mongoClient[collection]
let oid = try ObjectId("5bb216a8475fe42644993a41")
let document = try myCollection.findOne("_id" ==  oid)

如果 ObjectId 不存在，

document 将是 nil

另外，基于this document, findOne() method of Mongo DB takes much more resources than find() method. But under the hood of MongoKitten findOne() uses find() method: link

MongoKitten：检查 ObjectId 是否存在

MongoKitten: check if ObjectId exist

swift

mongokitten