scanner valuer example

scanval.go

package main

import (
	"database/sql"
	"database/sql/driver"
	"errors"
	"fmt"
	_ "github.com/mattn/go-sqlite3"
)

type YesNoEnum bool

func (yne YesNoEnum) Value() (driver.Value, error) {
	return bool(yne), nil
}

func (yne *YesNoEnum) Scan(value interface{}) error {
	// if value is nil, false
	if value == nil {
		// set the value of the pointer yne to YesNoEnum(false)
		*yne = YesNoEnum(false)
		return nil
	}
	if bv, err := driver.Bool.ConvertValue(value); err == nil {
		// if this is a bool type
		if v, ok := bv.(bool); ok {
			// set the value of the pointer yne to YesNoEnum(v)
			*yne = YesNoEnum(v)
			return nil
		}
	}
	// otherwise, return an error
	return errors.New("failed to scan YesNoEnum")
}

const (
	Yes YesNoEnum = true
	No            = false
)

type Customer struct {
	CustomerID int64
	Active     YesNoEnum
}

func main() {
	// open a database
	db, err := sql.Open("sqlite3", "./my.db")
	if err != nil {
		// fail!
		fmt.Println(err.Error())
		fmt.Println("ouch, database open failed")
		return
	}
	// close the database at the end of the function
	defer db.Close()

	//new Customer
	c := &Customer{
		CustomerID: 1,
		Active:     Yes,
	}
	// insert customer!
	_, err = db.Exec(
		"insert into customer (id, active) values (?, ?);",
		c.CustomerID, c.Active,
	)
	if err != nil {
		// fail!
		fmt.Println(err.Error())
		fmt.Println("I am sorry, your insert failed...better luck next time!")
		return
	}

	// get the customer record
	rows, err := db.Query("select id, active from customer")
	if err != nil {
		fmt.Println(err.Error())
		fmt.Println("I am sorry, your query failed...better luck next time!")
		return
	}
	// close the rows at the end of the function
	defer rows.Close()
	for rows.Next() {
		foundCustomer := new(Customer)
		if err := rows.Scan(
			&foundCustomer.CustomerID, &foundCustomer.Active,
		); err != nil {
			fmt.Println(err.Error())
			fmt.Println("I am sorry, your scanning failed...better luck next time!")
			return
		}
		// time to print our customers!!
		fmt.Println(foundCustomer)
	}
	if err := rows.Err(); err != nil {
		fmt.Println(err.Error())
		fmt.Println("I am sorry, your rows failed...better luck next time!")
		return
	}
}

Thanks! This helped me write https://github.com/blaskovicz/go-cryptkeeper