gorm - skynocover/Wiki-for-GoLang GitHub Wiki
gorm
go get -u github.com/jinzhu/gorm
import (
"github.com/jinzhu/gorm"
)
基本操作
db, err := gorm.Open("sqlite3", "test.db")
//db, err := gorm.Open("mysql", "user:password@(localhost)/dbname?charset=utf8&parseTime=True&loc=Local")
//若為本機(localhost)可以不填
if err != nil {
panic("failed to connect database")
}
defer db.Close()
db.AutoMigrate(&Product{}) //同步
db.Create(&Product{Code: "L1212", Price: 1000}) //創建
var product Product
db.First(&product, 1) //未指定則查詢id
db.First(&product, "code = ?", "L1212")
db.Model(&product).Update("Price", 2000)//更新
db.Delete(&product) //刪除
tag標記
type User struct {
gorm.Model //gorm內建模型
Name string `gorm:"default:'galeone'"`//設定預設值
Age sql.NullInt64
Birthday *time.Time
Email string `gorm:"type:varchar(100);unique_index"`
Role string `gorm:"size:255"` // 指定大小,default為255
MemberNumber *string `gorm:"unique;not null"` // 指定唯一並不為空
Num int `gorm:"AUTO_INCREMENT"` // 指定為自增
Address string `gorm:"index:addr"` // 指定index
IgnoreMe int `gorm:"-"` //忽略此字段
table
model
自動包含下列四種欄位,並且將ID設為主key
type Model struct {
ID uint `gorm:"primary_key"`
CreatedAt time.Time
UpdatedAt time.Time //會自動更新時間
DeletedAt *time.Time //刪除時會記錄時間,而不是直接刪除,可參考軟刪除
}
type User struct {
gorm.Model
Name string
}
db.Model(&user).Update("CreatedAt", time.Now()) //可用此方式修改建立或更新時間
table name
type User struct {} // default table name `users`
func (User) TableName() string { //set the table name
return "profiles"
}
//修改默認規則
gorm.DefaultTableNameHandler = func (db *gorm.DB, defaultTableName string) string {
return "prefix_" + defaultTableName;
}
表格操作
// 使用struct建立表格
db.Table("deleted_users").CreateTable(&User{})
var deleted_users []User
db.Table("deleted_users").Find(&deleted_users)
//// SELECT * FROM deleted_users; 會丟到宣告出來的struct陣列內
db.Table("deleted_users").Where("name = ?", "jinzhu").Delete()
//// DELETE FROM deleted_users WHERE name = 'jinzhu';
column
type User struct {
ID uint // column name is `id`
Birthday time.Time // column name is `birthday`
}
// Overriding Column Name
type Animal struct {
AnimalId int64 `gorm:"column:beast_id"` // set column name to `beast_id`
}
database
根據主key
db.First(&user)
//// SELECT * FROM users ORDER BY id LIMIT 1;
db.Take(&user) //隨機查詢
//// SELECT * FROM users LIMIT 1;
db.Last(&user)
//// SELECT * FROM users ORDER BY id DESC LIMIT 1;
db.Find(&users)
//// SELECT * FROM users;
db.First(&user, 10) //只有主key為int時可用
//// SELECT * FROM users WHERE id = 10;
where
db.Where("name = ?", "jinzhu").First(&user)
//// SELECT * FROM users WHERE name = 'jinzhu' limit 1;
db.Where("name = ?", "jinzhu").Find(&users)
//// SELECT * FROM users WHERE name = 'jinzhu';
db.Where("name <> ?", "jinzhu").Find(&users)
//// SELECT * FROM users WHERE name <> 'jinzhu';
db.Where("name IN (?)", []string{"jinzhu", "jinzhu 2"}).Find(&users)
//// SELECT * FROM users WHERE name in ('jinzhu','jinzhu 2');
db.Where("name LIKE ?", "%jin%").Find(&users)
//// SELECT * FROM users WHERE name LIKE '%jin%';
db.Where("name = ? AND age >= ?", "jinzhu", "22").Find(&users)
//// SELECT * FROM users WHERE name = 'jinzhu' AND age >= 22;
db.Where("updated_at > ?", lastWeek).Find(&users)
//// SELECT * FROM users WHERE updated_at > '2000-01-01 00:00:00';
db.Where("created_at BETWEEN ? AND ?", lastWeek, today).Find(&users)
//// SELECT * FROM users WHERE created_at BETWEEN '2000-01-01 00:00:00' AND '2000-01-08 00:00:00';
struct & map
// Struct
db.Where(&User{Name: "jinzhu", Age: 20}).First(&user)
//// SELECT * FROM users WHERE name = "jinzhu" AND age = 20 ORDER BY id LIMIT 1;
// Map
db.Where(map[string]interface{}{"name": "jinzhu", "age": 20}).Find(&users)
//// SELECT * FROM users WHERE name = "jinzhu" AND age = 20;
// 主键切片
db.Where([]int64{20, 21, 22}).Find(&users)
//// SELECT * FROM users WHERE id IN (20, 21, 22);
自動忽略0值或空值
db.Where(&User{Name: "jinzhu", Age: 0}).Find(&users)
//// SELECT * FROM users WHERE name = "jinzhu";
// 使用*可以避免空值問題
type User struct {
gorm.Model
Name string
Age *int
}
not
db.Not("name", "jinzhu").First(&user)
//// SELECT * FROM users WHERE name <> "jinzhu" ORDER BY id LIMIT 1;
db.Not("name", []string{"jinzhu", "jinzhu 2"}).Find(&users)
//// SELECT * FROM users WHERE name NOT IN ("jinzhu", "jinzhu 2");
db.Not([]int64{1,2,3}).First(&user)
//// SELECT * FROM users WHERE id NOT IN (1,2,3) ORDER BY id LIMIT 1;
db.Not([]int64{}).First(&user)
//// SELECT * FROM users ORDER BY id LIMIT 1;
db.Not("name = ?", "jinzhu").First(&user)
//// SELECT * FROM users WHERE NOT(name = "jinzhu") ORDER BY id LIMIT 1;
db.Not(User{Name: "jinzhu"}).First(&user)
//// SELECT * FROM users WHERE name <> "jinzhu" ORDER BY id LIMIT 1;
or
db.Where("role = ?", "admin").Or("role = ?", "super_admin").Find(&users)
//// SELECT * FROM users WHERE role = 'admin' OR role = 'super_admin';
db.Where("name = 'jinzhu'").Or(User{Name: "jinzhu 2"}).Find(&users)
//// SELECT * FROM users WHERE name = 'jinzhu' OR name = 'jinzhu 2';
db.Where("name = 'jinzhu'").Or(map[string]interface{}{"name": "jinzhu 2"}).Find(&users)
//// SELECT * FROM users WHERE name = 'jinzhu' OR name = 'jinzhu 2';
inline condition
db.First(&user, 23)
//// SELECT * FROM users WHERE id = 23;
// 若主key不是int則必須使用下面的方式
db.First(&user, "id = ?", "string_primary_key")
//// SELECT * FROM users WHERE id = 'string_primary_key';
db.Find(&user, "name = ?", "jinzhu")
//// SELECT * FROM users WHERE name = "jinzhu";
db.Find(&users, "name <> ? AND age > ?", "jinzhu", 20)
//// SELECT * FROM users WHERE name <> "jinzhu" AND age > 20;
db.Find(&users, User{Age: 20})
//// SELECT * FROM users WHERE age = 20;
db.Find(&users, map[string]interface{}{"age": 20})
//// SELECT * FROM users WHERE age = 20;
firstORinit
僅適用於struct或map
// 未找到
db.FirstOrInit(&user, User{Name: "non_existing"})
//// user 塞入 User{Name: "non_existing"}
// 找到
db.Where(User{Name: "Jinzhu"}).FirstOrInit(&user)
//// user 塞入 User{Id: 111, Name: "Jinzhu", Age: 20}
db.FirstOrInit(&user, map[string]interface{}{"name": "jinzhu"})
//// user 塞入 User{Id: 111, Name: "Jinzhu", Age: 20}
Attrs
若未找到則使用參數初始化strust
// 未找到
db.Where(User{Name: "non_existing"}).Attrs(User{Age: 20}).FirstOrInit(&user)
//// SELECT * FROM USERS WHERE name = 'non_existing' ORDER BY id LIMIT 1;
//// user 塞入 User{Name: "non_existing", Age: 20}
db.Where(User{Name: "non_existing"}).Attrs("age", 20).FirstOrInit(&user)
//// SELECT * FROM USERS WHERE name = 'non_existing' ORDER BY id LIMIT 1;
//// user 塞入 User{Name: "non_existing", Age: 20}
// 找到
db.Where(User{Name: "Jinzhu"}).Attrs(User{Age: 30}).FirstOrInit(&user)
//// SELECT * FROM USERS WHERE name = jinzhu' ORDER BY id LIMIT 1;
//// user 塞入 User{Id: 111, Name: "Jinzhu", Age: 20}
Assign
不管是否找到都賦值給struct並保存
// 未找到
db.Where(User{Name: "non_existing"}).Assign(User{Age: 20}).FirstOrInit(&user)
//// user 塞入 User{Name: "non_existing", Age: 20}
// 找到
db.Where(User{Name: "Jinzhu"}).Assign(User{Age: 30}).FirstOrInit(&user)
//// SELECT * FROM USERS WHERE name = jinzhu' ORDER BY id LIMIT 1;
//// user 塞入 User{Id: 111, Name: "Jinzhu", Age: 30}
子查詢
db.Where("amount > ?", db.Table("orders").Select("AVG(amount)").Where("state = ?", "paid").SubQuery()).Find(&orders)
// SELECT * FROM "orders" WHERE "orders"."deleted_at" IS NULL AND (amount > (SELECT AVG(amount) FROM "orders" WHERE (state = 'paid')));
select
db.Select("name, age").Find(&users)
//// SELECT name, age FROM users;
db.Select([]string{"name", "age"}).Find(&users)
//// SELECT name, age FROM users;
db.Table("users").Select("COALESCE(age,?)", 42).Rows()
//// SELECT COALESCE(age,'42') FROM users;
order
db.Order("age desc, name").Find(&users)
//// SELECT * FROM users ORDER BY age desc, name;
// 多字段排序
db.Order("age desc").Order("name").Find(&users)
//// SELECT * FROM users ORDER BY age desc, name;
// 覆盖排序
db.Order("age desc").Find(&users1).Order("age", true).Find(&users2)
//// SELECT * FROM users ORDER BY age desc; (users1)
//// SELECT * FROM users ORDER BY age; (users2)
Limit
db.Limit(3).Find(&users)
//// SELECT * FROM users LIMIT 3;
// -1 取消 Limit 条件
db.Limit(10).Find(&users1).Limit(-1).Find(&users2)
//// SELECT * FROM users LIMIT 10; (users1)
//// SELECT * FROM users; (users2)
offset
開始記錄前跳過的數目
db.Offset(3).Find(&users)
//// SELECT * FROM users OFFSET 3;
// -1 取消 Offset 条件
db.Offset(10).Find(&users1).Offset(-1).Find(&users2)
//// SELECT * FROM users OFFSET 10; (users1)
//// SELECT * FROM users; (users2)
count
總數,必須是最後一個動作,因為會覆蓋前面的select
db.Where("name = ?", "jinzhu").Or("name = ?", "jinzhu 2").Find(&users).Count(&count)
//// SELECT * from USERS WHERE name = 'jinzhu' OR name = 'jinzhu 2'; (users)
//// SELECT count(*) FROM users WHERE name = 'jinzhu' OR name = 'jinzhu 2'; (count)
db.Model(&User{}).Where("name = ?", "jinzhu").Count(&count)
//// SELECT count(*) FROM users WHERE name = 'jinzhu'; (count)
db.Table("deleted_users").Count(&count)
//// SELECT count(*) FROM deleted_users;
db.Table("deleted_users").Select("count(distinct(name))").Count(&count)
//// SELECT count( distinct(name) ) FROM deleted_users; (count)
Scan
將掃描結果丟至一個列
type Result struct {
Name string
Age int
}
var result Result
db.Table("users").Select("name, age").Where("name = ?", "Antonio").Scan(&result)
// 原生 SQL
db.Raw("SELECT name, age FROM users WHERE name = ?", "Antonio").Scan(&result)