// add model like this
package models

type Student struct {
    gorm.Model
    Name     string      `gorm:"type:varchar;not null"`
    Npm      uint64      `gorm:"type:bigint;not null"`
    Fak      string      `gorm:"type:varchar;not null"`
    Bid      string      `gorm:"type:varchar;not null"`
    Teachers []uint      `gorm:"type:text[]"`
}

type Teacher struct {
    gorm.Model
    Name   string `gorm:"type:varchar;not null"`
    Matkul string `gorm:"type:varchar;not null"`
}