组件分享之后端组件——对golang数据库/sql的通用扩展组件sqlx
背景
近期正在探索前端、后端、系统端各类常用组件与工具，对其一些常见的组件进行再次整理一下，形成标准化组件专题，后续该专题将包含各类语言中的一些常用组件。欢迎大家进行持续关注。
组件基本信息
- 组件：sqlx
- 开源协议：MIT License
内容
本节我们分享一个对golang数据库/sql的通用扩展组件sqlx
它在 go 的标准库上提供了一组扩展
database/sql。sql.DB,sql.TX,sql.Stmt, 等的 sqlx 版本。所有这些都保持底层接口不变，因此它们的接口是标准接口的超集。这使得使用 database/sql 与 sqlx 集成现有代码库相对容易。主要的附加概念是：
- 将行编组为结构（具有嵌入式结构支持）、映射和切片
- 命名参数支持，包括准备好的语句
Get并Select快速从查询转到结构/切片除了godoc API 文档之外，还有一些用户文档解释了如何
database/sql与 sqlx 一起使用。
安装方式如下：
go get github.com/jmoiron/sqlx
使用案例如下：
package main
import (
"database/sql"
"fmt"
"log"
_ "github.com/lib/pq"
"github.com/jmoiron/sqlx"
)
var schema = `
CREATE TABLE person (
first_name text,
last_name text,
email text
);
CREATE TABLE place (
country text,
city text NULL,
telcode integer
)`
type Person struct {
FirstName string `db:"first_name"`
LastName string `db:"last_name"`
Email string
}
type Place struct {
Country string
City sql.NullString
TelCode int
}
func main() {
// ping数据库尝试连接
// 使用sqlx.Open()实现sql.Open()语义
db, err := sqlx.Connect("postgres", "user=foo dbname=bar sslmode=disable")
if err != nil {
log.Fatalln(err)
}
// exec the schema or fail; multi-statement Exec behavior varies between
// database drivers; pq will exec them all, sqlite3 won't, ymmv
db.MustExec(schema)
tx := db.MustBegin()
tx.MustExec("INSERT INTO person (first_name, last_name, email) VALUES ($1, $2, $3)", "Jason", "Moiron", "[email protected]")
tx.MustExec("INSERT INTO person (first_name, last_name, email) VALUES ($1, $2, $3)", "John", "Doe", "[email protected]")
tx.MustExec("INSERT INTO place (country, city, telcode) VALUES ($1, $2, $3)", "United States", "New York", "1")
tx.MustExec("INSERT INTO place (country, telcode) VALUES ($1, $2)", "Hong Kong", "852")
tx.MustExec("INSERT INTO place (country, telcode) VALUES ($1, $2)", "Singapore", "65")
// Named queries can use structs, so if you have an existing struct (i.e. person := &Person{}) that you have populated, you can pass it in as &person
tx.NamedExec("INSERT INTO person (first_name, last_name, email) VALUES (:first_name, :last_name, :email)", &Person{"Jane", "Citizen", "[email protected]"})
tx.Commit()
// Query the database, storing results in a []Person (wrapped in []interface{})
people := []Person{}
db.Select(&people, "SELECT * FROM person ORDER BY first_name ASC")
jason, john := people[0], people[1]
fmt.Printf("%#v\n%#v", jason, john)
// Person{FirstName:"Jason", LastName:"Moiron", Email:"[email protected]"}
// Person{FirstName:"John", LastName:"Doe", Email:"[email protected]"}
// You can also get a single result, a la QueryRow
jason = Person{}
err = db.Get(&jason, "SELECT * FROM person WHERE first_name=$1", "Jason")
fmt.Printf("%#v\n", jason)
// Person{FirstName:"Jason", LastName:"Moiron", Email:"[email protected]"}
// if you have null fields and use SELECT *, you must use sql.Null* in your struct
places := []Place{}
err = db.Select(&places, "SELECT * FROM place ORDER BY telcode ASC")
if err != nil {
fmt.Println(err)
return
}
usa, singsing, honkers := places[0], places[1], places[2]
fmt.Printf("%#v\n%#v\n%#v\n", usa, singsing, honkers)
// Place{Country:"United States", City:sql.NullString{String:"New York", Valid:true}, TelCode:1}
// Place{Country:"Singapore", City:sql.NullString{String:"", Valid:false}, TelCode:65}
// Place{Country:"Hong Kong", City:sql.NullString{String:"", Valid:false}, TelCode:852}
// Loop through rows using only one struct
place := Place{}
rows, err := db.Queryx("SELECT * FROM place")
for rows.Next() {
err := rows.StructScan(&place)
if err != nil {
log.Fatalln(err)
}
fmt.Printf("%#v\n", place)
}
// Place{Country:"United States", City:sql.NullString{String:"New York", Valid:true}, TelCode:1}
// Place{Country:"Hong Kong", City:sql.NullString{String:"", Valid:false}, TelCode:852}
// Place{Country:"Singapore", City:sql.NullString{String:"", Valid:false}, TelCode:65}
// Named queries, using `:name` as the bindvar. Automatic bindvar support
// which takes into account the dbtype based on the driverName on sqlx.Open/Connect
_, err = db.NamedExec(`INSERT INTO person (first_name,last_name,email) VALUES (:first,:last,:email)`,
map[string]interface{}{
"first": "Bin",
"last": "Smuth",
"email": "[email protected]",
})
// Selects Mr. Smith from the database
rows, err = db.NamedQuery(`SELECT * FROM person WHERE first_name=:fn`, map[string]interface{}{"fn": "Bin"})
// Named queries can also use structs. Their bind names follow the same rules
// as the name -> db mapping, so struct fields are lowercased and the `db` tag
// is taken into consideration.
rows, err = db.NamedQuery(`SELECT * FROM person WHERE first_name=:first_name`, jason)
// batch insert
// batch insert with structs
personStructs := []Person{
{FirstName: "Ardie", LastName: "Savea", Email: "[email protected]"},
{FirstName: "Sonny Bill", LastName: "Williams", Email: "[email protected]"},
{FirstName: "Ngani", LastName: "Laumape", Email: "[email protected]"},
}
_, err = db.NamedExec(`INSERT INTO person (first_name, last_name, email)
VALUES (:first_name, :last_name, :email)`, personStructs)
// batch insert with maps
personMaps := []map[string]interface{}{
{"first_name": "Ardie", "last_name": "Savea", "email": "[email protected]"},
{"first_name": "Sonny Bill", "last_name": "Williams", "email": "[email protected]"},
{"first_name": "Ngani", "last_name": "Laumape", "email": "[email protected]"},
}
_, err = db.NamedExec(`INSERT INTO person (first_name, last_name, email)
VALUES (:first_name, :last_name, :email)`, personMaps)
}
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