Scopes 允许您轻松地复用常见的逻辑

查询

func AmountGreaterThan1000(db *gorm.DB) *gorm.DB {
  return db.Where("amount > ?", 1000)
}
func PaidWithCreditCard(db *gorm.DB) *gorm.DB {
  return db.Where("pay_mode_sign = ?", "C")
}
func PaidWithCod(db *gorm.DB) *gorm.DB {
  return db.Where("pay_mode_sign = ?", "C")
}
func OrderStatus(status []string) func (db *gorm.DB) *gorm.DB {
  return func (db *gorm.DB) *gorm.DB {
    return db.Where("status IN (?)", status)
  }
}
db.Scopes(AmountGreaterThan1000, PaidWithCreditCard).Find(&orders)
// 查找所有金额大于 1000 的信用卡订单
db.Scopes(AmountGreaterThan1000, PaidWithCod).Find(&orders)
// 查找所有金额大于 1000 的 COD 订单
db.Scopes(AmountGreaterThan1000, OrderStatus([]string{"paid", "shipped"})).Find(&orders)
// 查找所有金额大于1000 的已付款或已发货订单

分页

func Paginate(r *http.Request) func(db *gorm.DB) *gorm.DB {
  return func (db *gorm.DB) *gorm.DB {
    page, _ := strconv.Atoi(r.Query("page"))
    if page == 0 {
      page = 1
    }
    pageSize, _ := strconv.Atoi(r.Query("page_size"))
    switch {
    case pageSize > 100:
      pageSize = 100
    case pageSize <= 0:
      pageSize = 10
    }
    offset := (page - 1) * perPasge
    return db.Offset(offset).Limit(pageSize)
  }
}
db.Scopes(Paginate(r)).Find(&users)
db.Scopes(Paginate(r)).Find(&articles)

更新

func CurOrganization(r *http.Request) func(db *gorm.DB) *gorm.DB {
  return func (db *gorm.DB) *gorm.DB {
    org := r.Query("org")
    if org != "" {
      var organization Organization
      if db.Session(&Session{}).First(&organization, "name = ?", org).Error == nil {
        return db.Where("organization_id = ?", org.ID)
      }
    }
    db.AddError("invalid organization")
    return db
  }
}