gorm系列-更新

目录

• gorm更新操作
  • 无hooks更新
  • 使用sql表达式更新
  • 修改hooks中的值

gorm更新操作

更新所有字段

save()默认会更新该对象的所有字段，即使你没有赋值。

package main

import (
	"github.com/jinzhu/gorm"
	_ "github.com/jinzhu/gorm/dialects/mysql"
)

//1. 定义模型
type user struct {
	gorm.model
	name string
	age byte
	active bool
}

func main() {
	//2. 连接mysql数据库
	db, err := gorm.open("mysql","root:123456@tcp(127.0.0.1:3306)/db?charset=utf8mb4&parsetime=true&loc=local")
	if err != nil {
		panic(err)
	}
	defer db.close()
	//3. 把模型与数据库中的表对应起来
	db.automigrate(&user{})
	//4. 创建
	//u1 := user{name:"zisefeizhu", age: 22, active: true}
	//db.create(&u1)
	//u2 := user{name:" jingxing", age: 21, active:false}
	//db.create(&u2)
	//5. 查询
	var user user
	db.first(&user)
	////6. 更新
	user.name = "zisefeizhu"
	user.age = 23
	db.debug().save(&user)  //默认会修改所有字段
	//[2020-04-27 16:07:02]  [0.99ms]  update `users` set `created_at` = '2020-04-27 16:06:17', `updated_at` = '2020-04-27 16:07:02', `deleted_at` = null, `name` = 'zisefeizhu', `age` = 23, `active` = true  where `users`.`deleted_at` is null and `users`.`id` = 1
	//[1 rows affected or returned ] 
}

更新修改字段

如果你只希望更新指定字段，可以使用update或者updates

// 更新单个属性，如果它有变化
db.model(&user).update("name", "hello")
//// update users set name='hello', updated_at='2013-11-17 21:34:10' where id=111;

// 根据给定的条件更新单个属性
db.model(&user).where("active = ?", true).update("name", "hello")
//// update users set name='hello', updated_at='2013-11-17 21:34:10' where id=111 and active=true;

// 使用 map 更新多个属性，只会更新其中有变化的属性
db.model(&user).updates(map[string]interface{}{"name": "hello", "age": 18, "active": false})
//// update users set name='hello', age=18, active=false, updated_at='2013-11-17 21:34:10' where id=111;

// 使用 struct 更新多个属性，只会更新其中有变化且为非零值的字段
db.model(&user).updates(user{name: "hello", age: 18})
//// update users set name='hello', age=18, updated_at = '2013-11-17 21:34:10' where id = 111;

// 警告：当使用 struct 更新时，gorm只会更新那些非零值的字段
// 对于下面的操作，不会发生任何更新，"", 0, false 都是其类型的零值
db.model(&user).updates(user{name: "", age: 0, active: false})

db.debug().save(&user)  //默认会修改所有字段
///[2020-04-27 16:10:09]  [105.20ms]  update `users` set `created_at` = '2020-04-27 16:06:17', `updated_at` = '2020-04-27 16:10:09', `deleted_at` = null, `name` = 'zisefeizhu', `age` = 23, `active` = true  where `users`.`deleted_at` is null and `users`.`id` = 1
//[1 rows affected or returned ]
db.debug().model(&user).update("name","gengpan")
//[2020-04-27 16:10:09]  [0.99ms]  update `users` set `name` = 'gengpan', `updated_at` = '2020-04-27 16:10:09'  where `users`.`deleted_at` is null and `users`.`id` = 1  
//[1 rows affected or returned ] 

更新选定字段

如果你想更新或忽略某些字段，你可以使用 select，omit

db.model(&user).select("name").updates(map[string]interface{}{"name": "hello", "age": 18, "active": false})
//// update users set name='hello', updated_at='2013-11-17 21:34:10' where id=111;

db.model(&user).omit("name").updates(map[string]interface{}{"name": "hello", "age": 18, "active": false})
//// update users set age=18, active=false, updated_at='2013-11-17 21:34:10' where id=111;

package main

import (
   "github.com/jinzhu/gorm"
   _ "github.com/jinzhu/gorm/dialects/mysql"
)

//1. 定义模型
type user struct {
   gorm.model
   name string
   age byte
   active bool
}

func main() {
   //2. 连接mysql数据库
   db, err := gorm.open("mysql","root:123456@tcp(127.0.0.1:3306)/db?charset=utf8mb4&parsetime=true&loc=local")
   if err != nil {
      panic(err)
   }
   defer db.close()
   //3. 把模型与数据库中的表对应起来
   db.automigrate(&user{})
   //4. 创建
   //u1 := user{name:"zisefeizhu", age: 22, active: true}
   //db.create(&u1)
   //u2 := user{name:" jingxing", age: 21, active:false}
   //db.create(&u2)
   //5. 查询
   var user user
   db.first(&user)
   ////6. 更新
   user.name = "zisefeizhu"
   user.age = 23
   //db.debug().save(&user)  //默认会修改所有字段
   //db.debug().model(&user).update("name","gengpan")
   m1 := map[string]interface{}{
      "name":"yike",
      "age":22,
      "active":true,
   }
   db.debug().model(&user).updates(m1)  //m1列出来的所有字段都会更新
   //[2020-04-27 16:17:00]  [0.99ms]  update `users` set `active` = true, `age` = 22, `name` = 'yike', `updated_at` = '2020-04-27 16:17:00'  where `users`.`deleted_at` is null and `users`.`id` = 1  
   //[1 rows affected or returned ] 
   db.debug().model(&user).select("age").update(m1)  //只更新age字段
   //[2020-04-27 16:17:00]  [0.97ms]  update `users` set `age` = 22, `updated_at` = '2020-04-27 16:17:00'  where `users`.`deleted_at` is null and `users`.`id` = 1  
   //[0 rows affected or returned ] 
   db.debug().model(&user).omit("active").updates(m1)  //排除m1中的active更新其它字段
   //[2020-04-27 16:17:00]  [1.01ms]  update `users` set `age` = 22, `name` = 'yike', `updated_at` = '2020-04-27 16:17:00'  where `users`.`deleted_at` is null and `users`.`id` = 1  
   //[0 rows affected or returned ] 
}

无hooks更新

上面的更新操作会自动运行 model 的 beforeupdate, afterupdate 方法，更新 updatedat 时间戳, 在更新时保存其 associations, 如果你不想调用这些方法，你可以使用 updatecolumn， updatecolumns

// 更新单个属性，类似于 `update`
db.model(&user).updatecolumn("name", "hello")
//// update users set name='hello' where id = 111;

// 更新多个属性，类似于 `updates`
db.model(&user).updatecolumns(user{name: "hello", age: 18})
//// update users set name='hello', age=18 where id = 111;

批量更新

批量更新时hooks（钩子函数）不会运行

db.table("users").where("id in (?)", []int{10, 11}).updates(map[string]interface{}{"name": "hello", "age": 18})
//// update users set name='hello', age=18 where id in (10, 11);

// 使用 struct 更新时，只会更新非零值字段，若想更新所有字段，请使用map[string]interface{}
db.model(user{}).updates(user{name: "hello", age: 18})
//// update users set name='hello', age=18;

// 使用 `rowsaffected` 获取更新记录总数
db.model(user{}).updates(user{name: "hello", age: 18}).rowsaffected

使用sql表达式更新

先查询表中的第一条数据保存至user变量

var user user
db.first(&user)
db.model(&user).update("age", gorm.expr("age * ? + ?", 2, 100))
//// update `users` set `age` = age * 2 + 100, `updated_at` = '2020-02-16 13:10:20'  where `users`.`id` = 1;

db.model(&user).updates(map[string]interface{}{"age": gorm.expr("age * ? + ?", 2, 100)})
//// update "users" set "age" = age * '2' + '100', "updated_at" = '2020-02-16 13:05:51' where `users`.`id` = 1;

db.model(&user).updatecolumn("age", gorm.expr("age - ?", 1))
//// update "users" set "age" = age - 1 where "id" = '1';

db.model(&user).where("age > 10").updatecolumn("age", gorm.expr("age - ?", 1))
//// update "users" set "age" = age - 1 where "id" = '1' and quantity > 10;

var user user
db.first(&user)
////6. 更新
//user.name = "zisefeizhu"
//user.age = 23
//db.debug().save(&user)  //默认会修改所有字段
//db.debug().model(&user).update("name","gengpan")
db.model(&user{}).update("age",gorm.expr("age+?",2))

修改hooks中的值

如果你想修改 beforeupdate, beforesave 等 hooks 中更新的值，你可以使用 scope.setcolumn

func (user *user) beforesave(scope *gorm.scope) (err error) {
  if pw, err := bcrypt.generatefrompassword(user.password, 0); err == nil {
    scope.setcolumn("encryptedpassword", pw)
  }
}

其它更新选项

// 为 update sql 添加其它的 sql
db.model(&user).set("gorm:update_option", "option (optimize for unknown)").update("name", "hello")
//// update users set name='hello', updated_at = '2013-11-17 21:34:10' where id=111 option (optimize for unknown);