sequelize.customerLoader.ts

export class SequelizeCustomerLoader implements CustomerLoader {
    async get(id: string): Promise<Customer> {
        const customers = await SequelizeCustomerModel
            .findAll({
                where: { id: id },
                limit: 1
            })
            .then(this.mapToCustomers)
        return customers[0] || Promise.reject(new CustomerNotFoundError())
    }

    private mapToCustomers(customers: SequelizeCustomerModel[]): Customer[] {
        return customers.map(customer => new Customer(
            customer.id,
            customer.name,
            customer.email,
            customer.phone
        ))
    }
}