go__xormtuto/main.go

/*
When using xorm, you can create multiple orm engines, an engine means a database.
*/
package main

import (
	// Core.
	"fmt"
	"os"

	// SQLite 3
	_ "github.com/mattn/go-sqlite3"

	// MySQL. Use either driver.
	// _ "github.com/go-sql-driver/mysql"
	// _ "github.com/ziutek/mymysql"

	// PostgreSQL
	// _ "github.com/lib/pq"

	// SQL Server
	// _ "github.com/lunny/godbc"

	// XORM.
	"github.com/go-xorm/xorm"

	// Others.
	// "github.com/davecgh/go-spew/spew"
	"github.com/go-xorm/core"
)

func check(err error) {
	if err != nil {
		fmt.Println(err.Error())
		os.Exit(1)
	}
}

func NewOrm() *xorm.Engine {
	// NewEngine parameters are those of the SQL driver: driver and DSN.
	engine, err := xorm.NewEngine("sqlite3", "./test.db")
	check(err)
	fmt.Println("ORM loaded")
	return engine
}

func setupLogging(engine *xorm.Engine) {
	// Enable built-in Logging features.
	engine.ShowSQL = true
	engine.ShowDebug = true
	engine.ShowErr = true
	engine.ShowWarn = true

	// Optional: declare a custom logger.
	f, err := os.Create("sql.log")
	check(err)
	engine.SetLogger(xorm.NewSimpleLogger(f))
}

func setupConnections(engine *xorm.Engine) {
	// Optional: limit connections.
	const CONNECTION_LIMIT = 4

	engine.SetMaxOpenConns(CONNECTION_LIMIT)
	// The number of idle connections is bound by the number of open ones.
	engine.SetMaxIdleConns(CONNECTION_LIMIT)
}

/*
------------------------------+---------------------------------------+------------
go type's kind			value method				xorm type
------------------------------+---------------------------------------+------------
implemented Conversion		Conversion.ToDB / Conversion.FromDB	Text
int, int8, int16, int32							Int
uint, uint8, uint16, uint32						Int
int64, uint64								BigInt
float32									Float
float64									Double
complex64, complex128		json.Marshal / json.UnMarshal		Varchar(64)
[]uint8									Blob
array, slice, other maps	json.Marshal / json.UnMarshal		Text
bool				1 or 0					Bool
string									Varchar(255)
time.Time								DateTime
cascade struct			primary key field value			BigInt
struct				json.Marshal / json.UnMarshal		Text
Others									Text
------------------------------+---------------------------------------+------------
 */
func setupMapping(engine *xorm.Engine) {
	same := core.SameMapper{}
	gonic := core.GonicMapper{}
	snake := core.SnakeMapper{}

	// Global mapping. Default is snake.
	// engine.SetMapper(same)

	// Table-specific mapping.
	engine.SetTableMapper(gonic)

	// Column-specific mapping.
	engine.SetColumnMapper(snake)

	prefixedMapper := core.NewPrefixMapper(same, "prefix")
	wrappedMapper := core.NewSuffixMapper(prefixedMapper, "suffix")
	decoratedMapper := core.NewCacheMapper(wrappedMapper)
	engine.SetMapper(decoratedMapper)
}

func main() {
	var engine *xorm.Engine = NewOrm()

	setupLogging(engine)
	setupConnections(engine)
	setupMapping(engine)

	// Not needed: called automatically on exit.
	engine.Close()
	fmt.Println("ORM closed")
}