Gorm 中如何跨文件共享 DB 实例？

// model/user.go
package model

import "gorm.io/gorm"

var db *gorm.db

type user struct {
    id       int
    mobile    string
}

package main

import (
    "fmt"

    "github.com/gin-gonic/gin"
    "gorm.io/driver/mysql"
    "gorm.io/gorm"

    "model"
)

func main() {
    dsn := "root:nexon8888@tcp(127.0.0.1:3306)/iapplus?charset=utf8mb4&parsetime=true&loc=local"
    db, err := gorm.open(mysql.open(dsn), &gorm.config{})
    if err != nil {
        fmt.println("数据库连接错误")
        return
    }
    model.db = db

    // 下面代码与上面示例相同
}

// constants/db.go
package constants

import (
    "github.com/gin-gonic/gin"
    "gorm.io/driver/mysql"
    "gorm.io/gorm"
)

var db *gorm.db

func init() {
    dsn := "root:nexon8888@tcp(127.0.0.1:3306)/iapplus?charset=utf8mb4&parsetime=true&loc=local"
    db, err := gorm.open(mysql.open(dsn), &gorm.config{})
    if err != nil {
        log.fatal("数据库连接错误")
    }
    db = db
}

package main

import (
    "fmt"

    "github.com/gin-gonic/gin"

    "constants"
)

func main() {
    // 下面代码与上面示例相同
}