11-gorm-V2-02-创建数据

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

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("OKn")
		sqlDB.SetMaxIdleConns(10)
		sqlDB.SetMaxOpenConns(100)
		sqlDB.SetConnMaxLifetime(time.Hour)
	}
	return
}

使用指定字段

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

排除指定字段

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

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)

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)
}

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
}

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("OKn")
		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)

SkipHooks 会话模式可以跳过钩子。

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

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