How to set up Unique Compound Index in NestJS (MongoDB) - mongodb

Question

Hey i have a schema for user with an unique email:
#Schema()
export class User {
#Prop()
firstName!: string;
#Prop()
lastName!: string;
#Prop({
unique: true,
})
email!: string;
#Prop({ nullable: true })
password?: string;
}
But now i want to extend this. I wanna have Groups with their own users. I would create a collection of groups and add their id to the users like:
#Schema()
export class User {
#Prop()
groupId: string;
#Prop()
firstName!: string;
...
}
For each group the email should be unique. That means in the collection of users there could be duplicate emails but they should be unique by group which is named Unique Compound Index i guess.
How do i set this up in NestJS?

Answer 1

Looks like its not possible to achieve it solely by use of the #nestjs/mongoose decorators, however its possible to declare index by use of SchemaFactory
#Schema()
export class User {
#Prop()
groupId: string;
#Prop()
firstName!: string;
...
}
export const UserSchema = SchemaFactory.createForClass(User);
UserSchema.index({ groupId: 1, firstName: 1 }, { unique: true });
Then you must do either create migration to create this index or enable auto-index feature
#Schema({
autoIndex: true, // <--
})
export class User {
#Prop()
groupId: string;
#Prop()
firstName!: string;
...
}