英文:
How to share globally the MySQL driver on different handlers on GoLang
问题
我想从不同的处理程序中调用数据库，这是我的mysql.go代码：
package common
import (
"database/sql"
"fmt"
_ "github.com/go-sql-driver/mysql"
)
var db *sql.DB
var err error
// 连接数据库
func connectDB() {
db, err = sql.Open("mysql", "root@tcp(localhost:3306)/mysqlapi")
if err != nil {
fmt.Println(err.Error())
}
defer db.Close()
// 测试连接
err = db.Ping()
if err != nil {
fmt.Println(err.Error())
}
// 表迁移
stmt, err := db.Prepare("CREATE TABLE person (id int NOT NULL AUTO_INCREMENT, first_name varchar(40), last_name varchar(40), PRIMARY KEY (id));")
if err != nil {
fmt.Println(err.Error())
}
_, err = stmt.Exec()
if err != nil {
fmt.Println(err.Error())
} else {
fmt.Println("Person Table successfully migrated....")
}
}
这是我想要做的，但我不知道如何从common包中调用不同包中的db（我尝试了common.db，但它不起作用）：
package models
import (
"github.com/colombia9503/RESTful-Mysql/common"
)
type User struct {
Id int
First_Name string
Last_Name string
}
var Users = new(users)
type users struct{}
func (users) SelectAll() ([]*User, error) {
var users []*User
rows, err := common.db.Query("select id, first_name, last_name from person;")
if err != nil {
panic(err)
}
for rows.Next() {
// 一些代码...
}
return users, err
}
func (users) SelectOne(id string) (*User, error) {
// 一些代码...
}
func (users) Insert(name, last_name string) (*User, error) {
// 一些代码...
}
func (users) Update(id, name, last_name string) error {
// 一些代码...
}
func (users) Delete(id string) error {
// 一些代码...
}
你可以尝试将common.db更改为common.DB，因为在common包中，db是一个全局变量，需要以大写字母开头才能在其他包中访问。
英文:
I want to call db from the different handlers, This is my mysql.go:
<!-- language: golang -->
package common
import (
"database/sql"
"fmt"
_ "github.com/go-sql-driver/mysql"
)
var db *sql.DB
var err error
//db connection
func connectDB() {
db, err = sql.Open("mysql", "root@tcp(localhost:3306)/mysqlapi")
if err != nil {
fmt.Println(err.Error())
}
defer db.Close()
//test connection
err = db.Ping()
if err != nil {
fmt.Println(err.Error())
}
//table migration
stmt, err := db.Prepare("CREATE TABLE person (id int NOT NULL AUTO_INCREMENT, first_name varchar(40), last_name varchar(40), PRIMARY KEY (id));")
if err != nil {
fmt.Println(err.Error())
}
_, err = stmt.Exec()
if err != nil {
fmt.Println(err.Error())
} else {
fmt.Println("Person Table successfully migrated....")
}
}
this is what i want to do, but i don't know how i call db from common package into a different package (i tried common.db but it doesn't works):
<!-- language: golang -->
package models
import (
"github.com/colombia9503/RESTful-Mysql/common"
)
type User struct {
Id int
First_Name string
Last_Name string
}
var Users = new(users)
type users struct{}
func (users) SelectAll() ([]*User, error) {
var users []*User
rows, err := common.db.Query("select id, first_name, last_name from person;")
if err != nil {
panic(err)
}
for rows.Next() {
some code..
}
return users, err
}
func (users) SelectOne(id string) (*User, error) {
some code..
}
func (users) Insert(name, last_name string) (*User, error) {
some code..
}
func (users) Update(id, name, last_name string) error {
some code..
}
func (users) Delete(id string) error {
some code..
}
答案1
得分: 0
你需要像这样编写你的 db 变量：
package common
import (
"database/sql"
"fmt"
_ "github.com/go-sql-driver/mysql"
)
var Db *sql.DB
var Err error
在 Golang 中，大写字母表示将其导出到包外部。你可以在这里了解更多信息：这里
英文:
You need to write your db var like this :
package common
import (
"database/sql"
"fmt"
_ "github.com/go-sql-driver/mysql"
)
var Db *sql.DB
var Err error
In Golang Capital letter means exporting it to outside of the package.you can learn more about this here
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