DeprecationWarning: current Server Discovery and Monitoring engine is deprecated, and will be removed in a future version. To use the new Server Discover and Monitoring engine, pass option { useUnifiedTopology: true } to the MongoClient constructor

mongoose.connect("paste db link", {useUnifiedTopology: true, useNewUrlParser: true, useCreateIndex: true });

mongoose.connect(mongoConnectionString, {useNewUrlParser: true, useUnifiedTopology: true});

mongoose.connect("mongodb://localhost:27017/NAME", { useUnifiedTopology: true, useNewUrlParser: true });