How to check if that data already exist in the database during update (Mongoose And Express)

Question

How to do validations before saving the edited data in mongoose?

For example, if sample.name already exists in the database, the user will receive a som

Answer 1

For anybody falling on this old solution. There is a better way from the mongoose docs.

var s = new Schema({ name: { type: String, unique: true }});
s.path('name').index({ unique: true });