go-bindata 和 sql-migrate 用法

安装 go-bindata 

go get -u github.com/jteeuwen/go-bindata/...

This package converts any file into managable Go source code. Useful for embedding binary data into a go program. The file data is optionally gzip compressed before being converted to a raw byte slice.

这里我借助go-bindata 把我写好的sql文件，生成go源码，加入到工程中

安装 sql-migrate

go get -v github.com/rubenv/sql-migrate/...

sql-migrate

SQL Schema migration tool for Go. Based on gorp and goose.

这里我借助它 在数据库中 初始化一些我需要的表格 索引等

创建 postgres 用户及 数据库

postgres=# CREATE USER dbuser WITH PASSWORD '123456';
CREATE ROLE
postgres=# CREATE DATABASE exampledb OWNER dbuser;
CREATE DATABASE
postgres=# GRANT ALL PRIVILEGES ON DATABASE exampledb TO dbuser;
GRANT

新建 migrations 目录，新建一个sql文件

~/go/gopath/src/wjs/learnSqlMigrations $ ls
main.go  migrations
~/go/gopath/src/wjs/learnSqlMigrations/migrations $ ls
1_init.sql

sql 内容，创建student 和 people 表格，

~/go/gopath/src/wjs/learnSqlMigrations/migrations $ cat 1_init.sql 
-- +migrate Up
create table student (
	id text primary key,
	name varchar(100) unique not null,
	description text not null
);

CREATE TABLE people (id int);

-- +migrate Down
drop table student;
drop table people;

新建 main.go 文件

//go:generate go-bindata -prefix migrations -pkg bdata -o bdata/migrations_gen.go migrations
package main

import (
	"fmt"
	"time"
	"wjs/learnSqlMigrations/bdata"
	"github.com/pkg/errors"
	migrate "github.com/rubenv/sql-migrate"
	log "github.com/sirupsen/logrus"

	"github.com/jmoiron/sqlx"
	_ "github.com/lib/pq"
)

var g_db *sqlx.DB

// OpenDatabase opens the database and performs a ping to make sure the
// database is up.
func OpenDatabase(dsn string) (*sqlx.DB, error) {
	db, err := sqlx.Open("postgres", dsn)
	if err != nil {
		return nil, fmt.Errorf("database connection error: %s", err)
	}
	for {
		if err := db.Ping(); err != nil {
			log.Errorf("ping database error, will retry in 2s: %s", err)
			time.Sleep(2 * time.Second)
		} else {
			break
		}
	}
	return db, nil
}

func setPostgreSQLConnection() error {
	log.Info("connecting to postgresql")
	db, err := OpenDatabase("postgres://dbuser:123456@localhost/exampledb?sslmode=disable")
	if err != nil {
		return errors.Wrap(err, "database connection error")
	}
	g_db = db
	return nil
}

func runDatabaseMigrations() error {
	log.Info("applying database migrations")
	m := &migrate.AssetMigrationSource{
		Asset:    bdata.Asset,
		AssetDir: bdata.AssetDir,
		Dir:      "",
	}
	n, err := migrate.Exec(g_db.DB, "postgres", m, migrate.Up)
	if err != nil {
		return errors.Wrap(err, "applying migrations failed")
	}
	log.WithField("count", n).Info("migrations applied")

	return nil
}

func main() {
	setPostgreSQLConnection()
	err := runDatabaseMigrations()
	if err != nil {
		log.Error(err)
	}
}

运行 go generate

就会生成 migrations_gen.go 文件，里面保存了 1_init.sql 文件的内容

我们来看  main.go 第一行

//go:generate go-bindata -prefix migrations -pkg bdata -o bdata/migrations_gen.go migrations

-pkg 指定了生成的bindata文件包名是 bdata

-o bdata/migrations_gen.go 指定了生成bindata文件的位置

-prefix migrations  如果待转换文件路径前缀有 migrations 则，去掉这个前缀, 参考生成的migrations_gen.go源码

运行 go run main.go

exampledb=> \d
 public | gorp_migrations | table | dbuser
 public | people          | table | dbuser
 public | student         | table | dbuser