我正在尝试在Password表上创建一个外键，该键必须指向表id内的User列。但是当我尝试以下操作时，它不起作用。将foreign key不会产生。它只是user_id在password表内添加列名。

package schema

import (
"github.com/jinzhu/gorm"
_ "github.com/jinzhu/gorm/dialects/mysql"
)

type User struct {
    gorm.Model
    FirstName string `gorm:"not null"`
    LastName string `gorm:"not null"`
    Email string `gorm:"type:varchar(100);unique_index"`
    IsActive bool `gorm:"not null"`
    IsVerified bool `gorm:"not null"`
}

type Password struct {
    gorm.Model
    Password string `gorm:"not null"`
    UserId int `gorm:"not null"`
    User User `gorm:"foreignkey:UserId;association_foreignkey:id"`
}


func SyncDB(db *gorm.DB) {

    db.AutoMigrate(&User{})
    db.AutoMigrate(&Password{})
}

我究竟做错了什么？如何在Password表内部使外键指向User表？