Defining indexes or unique fields in MongoDB in Golang requires one to create it manually for each field. It takes the index definition away from the main model definition.

I would like to propose a method to create indexes for each field using the StructTags

type User struct {
	Id       primitive.ObjectID
	Email    string             `mongo:"unique"`
}

I created something similar for this here: Migrate() function
The above-mentioned method is definitely not perfect, since I created it for one-time use.

The working on the method can be tested here: ShauryaAg/ProductAPI

I would love to work on this.