Gorm Can't Insert Value into Sqlite

Question

I use dao layer to init sqlitedb and try to insert a col into db in main.go

The Problem is When the main.go is finish and the database is created.But No any data in db..

my model.go is here

package model

import "gorm.io/gorm"

type User struct {
    gorm.Model
    Username string `json:"username"`
    Password string `json:"password"`
}

and my gorm dao.go is here

package dao

import (
    "go_blog/model"
    "log"

    "gorm.io/driver/sqlite"
    "gorm.io/gorm"
)

type Manager interface {
    AddUser(user *model.User)
}

type manager struct {
    db *gorm.DB
}

var Mgr Manager

func init() {
    db, err := gorm.Open(sqlite.Open("database/blog.db"), &gorm.Config{})
    if err != nil {
        log.Fatal("Failed to INIT db:", err)
    }
    Mgr = &manager{db: db}
    db.AutoMigrate(&model.User{})
    log.Fatal("Init DB Successful")

}

func (mgr *manager) AddUser(user *model.User) {
    mgr.db.Create(user)
}

when I use main.go to run the Mgr.AddUser function,I look into sqlite db,but the DB is no any data in there...So Confuse..

main.go is here

package main

import (
    "go_blog/dao"
    "go_blog/model"
)

func main() {
    user := model.User{
        Username: "tom",
        Password: "123",
    }
    dao.Mgr.AddUser(&user)
}