如何获得关联模型

Question

I have this model:

type Process struct {
    Asset Asset  `json:"asset" binding:"required"`
    Buyer Person `json:"buyer" binding:"required"`
    Payer Person `json:"payer" binding:"required"`
}

asset and person is a foreign key, this is how i set it to be foregin key (if there is a better way you can also tell me):

type DBProcess struct {
    DBBase
    Asset uint `gorm:"column:asset_id" json:"-"`
    Buyer uint `gorm:"column:buyer_id" json:"-"`
    Payer uint `gorm:"column:payer_id" json:"-"`
}

func (DBProcess) TableName() string {
    return "t_processes"
}

------------ main func -----------

db.Model(&models.DBProcess{}).AddForeignKey("asset_id", "t_assets(id)", "RESTRICT", "RESTRICT")
db.Model(&models.DBProcess{}).AddForeignKey("buyer_id", "t_persons(id)", "RESTRICT", "RESTRICT")
db.Model(&models.DBProcess{}).AddForeignKey("payer_id", "t_persons(id)", "RESTRICT", "RESTRICT")

for other tables of course, I want to search process by the Asset id, how can I do that? I don't know if you need more information, but if you do, please tell me what information I can add so the question will be more understandable