mongoose save a document
const Person = mongoose.model('Person', Schema({
name: String,
rank: String
}));
const doc = new Person({
name: 'Will Riker',
rank: 'Commander'
});
// Inserts a new document with `name = 'Will Riker'` and
// `rank = 'Commander'`
await doc.save();
const person = await Person.findOne();
person.name; // 'Will Riker'