使用gorm.Scopes函数实现复用查询逻辑示例

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)
  }
}
// 查找所有金额大于 1000 的信用卡订单
db.Scopes(AmountGreaterThan1000, PaidWithCreditCard).Find(&orders)
// 查找所有金额大于 1000 的 COD 订单
db.Scopes(AmountGreaterThan1000, PaidWithCod).Find(&orders)
// 查找所有金额大于1000 的已付款或已发货订单
db.Scopes(AmountGreaterThan1000, OrderStatus([]string{"paid", "shipped"})).Find(&orders)

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

// DeleteAction 通用删除动作
func DeleteAction(control dto.Control) gin.HandlerFunc {
 return func(c *gin.Context) {
  db, err := pkg.GetOrm(c)
        ...//省略了一些逻辑
  //数据权限检查
  p := GetPermissionFromContext(c)
        // 将Permission函数传入Scopes函数
  db = db.WithContext(c).Scopes(
   Permission(object.TableName(), p),
  ).Where(req.GetId()).Delete(object)
        ...//省略了一些逻辑
        // 检查操作的行数，如果操作的行数是0，说明没有权限
  if db.RowsAffected == 0 {
   response.Error(c, http.StatusForbidden, nil, "无权删除该数据")
   return
  }
  response.OK(c, object.GetId(), "删除成功")
  c.Next()
 }
}
// Permission函数的逻辑
// 根据不同 的数据范围枚举值，转换成不同的Where条件
func Permission(tableName string, p *DataPermission) func(db *gorm.DB) *gorm.DB {
 return func(db *gorm.DB) *gorm.DB {
  if !config.ApplicationConfig.EnableDP {
   return db
  }
  switch p.DataScope {
  case "2":
   return db.Where(tableName+".create_by in (select sys_user.user_id from sys_role_dept left join sys_user on sys_user.dept_id=sys_role_dept.dept_id where sys_role_dept.role_id = ?)", p.RoleId)
  case "3":
   return db.Where(tableName+".create_by in (SELECT user_id from sys_user where dept_id = ? )", p.DeptId)
  case "4":
   return db.Where(tableName+".create_by in (SELECT user_id from sys_user where sys_user.dept_id in(select dept_id from sys_dept where dept_path like ? ))", "%/"+pkg.IntToString(p.DeptId)+"/%")
  case "5":
   return db.Where(tableName+".create_by = ?", p.UserId)
  default:
   return db
  }
 }
}