# Scopes
Scopes 允許您輕松地復用常見的邏輯
## 查詢
```go
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)
// 查找所有金額大于 1000 的信用卡訂單
db.Scopes(AmountGreaterThan1000, PaidWithCod).Find(&orders)
// 查找所有金額大于 1000 的 COD 訂單
db.Scopes(AmountGreaterThan1000, OrderStatus([]string{"paid", "shipped"})).Find(&orders)
// 查找所有金額大于1000 的已付款或已發貨訂單
```
## 分頁
```go
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
```go
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
}
}
```
