02-创建数据

合集 - 【基础卷】----------------------------(40)

1.01-包引用和引用顺序2021-08-162.02-运算符号、标识符、注释、关键字2021-11-163.03-变量和作用域2021-11-164.02-常量（const）2021-11-165.03-数组（array）2022-12-056.04-切片（slice）2022-12-017.05-map2022-12-068.06-指针（pointer）2022-12-079.07-通道（channel）2022-12-0710.08-结构体（struct）2022-12-0811.01-if语句2022-12-1212.02-for循环2021-11-2113.04-select语句2022-12-2614.03-switch语句2021-11-1615.make()、new()2023-01-1016.copy（切片间复制）2021-08-1717.append（增加切片成员）2023-01-1218.delete（删除map的成员）2021-08-1619.panic&recover2023-01-0920.03-匿名函数和闭包2023-01-1121.01-函数简单使用2021-11-1722.02-形参和实参2021-11-2023.04-递归函数2021-11-2024.05-方法2021-11-2025.06-接口（interface）2022-10-0526.01-并发2021-11-2027.02-携程通讯2021-08-1828.03-携程同步2021-08-1929.01-连接和建表2022-02-12

30.02-创建数据2023-06-28

31.03-基本查询2023-06-2832.04-高级查询2023-06-2833.05-初始化2022-02-1434.06-更新数据2022-02-1735.07-删除数据2023-06-2836.08 事务2022-02-2237.根据操作系统程序自动选择不同常量2023-02-2138.golang字串的base64编码解码2022-05-0939.golang数据类型转换2022-01-1340.golang 时间/时间戳的获取和转换2021-11-24

收起

目录

• 1. 简单示例
• 2. 用指定的字段创建记录
• 3. 批量插入
  • 3.1 用数组切片创建
  • 3.2 CreateInBatches 批量创建
• 4. 创建钩子
  • 4.1 概念
  • 4.2 完整示例
  • 4.3 跳过钩子
• 5. 根据MAP 创建

1. 简单示例

db.Create(&liuBei)

• 完整示例

package main
 
import (
	"database/sql"
	"fmt"
	"gorm.io/driver/mysql"
	"gorm.io/gorm"
	"time"
)
 
type User struct {
	ID int64
	Age int64
	Name string
}
 
func main() {
	db,sqlDB,_ := connect()
	defer sqlDB.Close()
    liuBei := User{
    	Name: "LiuBei",
    	Age: 28,
	}
	db.Create(&liuBei)
 
}
 
func connect() (db *gorm.DB,sqlDB *sql.DB,err error) {
	dsn := "root:40010355@tcp(127.0.0.1:3306)/crow?charset=utf8&parseTime=True&loc=Local"
	db, err = gorm.Open(mysql.Open(dsn), &gorm.Config{})
	sqlDB,_ = db.DB()
	if err != nil {
		fmt.Printf(err.Error())
		defer sqlDB.Close()
	}else {
		fmt.Printf("OK\n")
		sqlDB.SetMaxIdleConns(10)
		sqlDB.SetMaxOpenConns(100)
		sqlDB.SetConnMaxLifetime(time.Hour)
	}
	return
}

2. 用指定的字段创建记录

• 使用指定字段

db.Select("name").Create(&liuBei)

• 排除指定字段

db.Omit("name").Create(&liuBei)

3. 批量插入

3.1 用数组切片创建

func main() {
	db,sqlDB,_ := connect()
	defer sqlDB.Close()
 
	var users = []User{{Name: "LiuBei",Age: 28}, {Name: "GuanYu",Age: 22}, {Name: "ZhangFei",Age: 20}}
	db.Create(&users)
    fmt.Println(users)
 
}

• 输出

OK
[{8 28 LiuBei} {9 22 GuanYu} {10 20 ZhangFei}]

• 数据库表结果

mysql> select * from users;
+----+------+----------+
| id | age  | name     |
+----+------+----------+
|  8 |   28 | LiuBei   |
|  9 |   22 | GuanYu   |
| 10 |   20 | ZhangFei |
+----+------+----------+
3 rows in set (0.00 sec)

3.2 CreateInBatches 批量创建

测试未成功，依然会创建5条数据。

func main() {
	db,sqlDB,_ := connect()
	defer sqlDB.Close()
 
	//db.Migrator().CreateTable(&User{})
	user := []User{{Name: "soldier_01"},{Name: "soldier_02"},{Name: "soldier_03"},{Name: "soldier_04"},{Name: "soldier_05"}}
    db.CreateInBatches(user, 3)
}

4. 创建钩子

4.1 概念

• GORM 允许用户定义的钩子
  BeforeSave, BeforeCreate, AfterSave, AfterCreate

• 创建

func (u *User) BeforeCreate(tx *gorm.DB) (err error) {
	u.Name = "Shi_Bing"
	return
}

4.2 完整示例

• 代码

示例中通过切片创建表，本应是 soldier_01到soldier_05。但因为 BeforeCreate方法的存在，实际表中name列都是 shi_bing

package main
 
import (
	"database/sql"
	"fmt"
	"gorm.io/driver/mysql"
	"gorm.io/gorm"
	"time"
)
 
type User struct {
	ID int64
	Age int64
	Name string
}
 
func (u *User) BeforeCreate(tx *gorm.DB) (err error) {
	u.Name = "Shi_Bing"
	return
}
 
 
func main() {
	db,sqlDB,_ := connect()
	defer sqlDB.Close()
	user := []User{{Name: "soldier_01"},{Name: "soldier_02"},{Name: "soldier_03"},{Name: "soldier_04"},{Name: "soldier_05"}}
	db.Create(&user)
	fmt.Println(user)
}
 
func connect() (db *gorm.DB,sqlDB *sql.DB,err error) {
	dsn := "root:40010355@tcp(127.0.0.1:3306)/crow?charset=utf8&parseTime=True&loc=Local"
	db, err = gorm.Open(mysql.Open(dsn), &gorm.Config{})
	sqlDB,_ = db.DB()
	if err != nil {
		fmt.Printf(err.Error())
		defer sqlDB.Close()
	}else {
		fmt.Printf("OK\n")
		sqlDB.SetMaxIdleConns(10)
		sqlDB.SetMaxOpenConns(100)
		sqlDB.SetConnMaxLifetime(time.Hour)
	}
	return
}

• 输出

OK
[{16 0 Shi_Bing} {17 0 Shi_Bing} {18 0 Shi_Bing} {19 0 Shi_Bing} {20 0 Shi_Bing}]

• 数据库表

mysql> select * from users;
+----+------+----------+
| id | age  | name     |
+----+------+----------+
| 16 |    0 | Shi_Bing |
| 17 |    0 | Shi_Bing |
| 18 |    0 | Shi_Bing |
| 19 |    0 | Shi_Bing |
| 20 |    0 | Shi_Bing |
+----+------+----------+
5 rows in set (0.00 sec)

4.3 跳过钩子

SkipHooks 会话模式可以跳过钩子。

db.Session(&gorm.Session{SkipHooks: true}).Create(&user)

5. 根据MAP 创建

	user := map[string]interface{}{
		"Name":"GuanYu",
		"Age":22,
	}
	db.Model(&User{}).Create(user)	

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