Fs02/grimoire

// Package mysql wraps mysql driver as an adapter for grimoire.
//
// Usage:
//    // open mysql connection.
//    adapter, err := mysql.Open("root@(127.0.0.1:3306)/grimoire_test?charset=utf8&parseTime=True&loc=Local")
//    if err != nil {
//        panic(err)
//    }
//    defer adapter.Close()
//
//    // initialize grimoire's repo.
//    repo := grimoire.New(adapter)
package mysql

import (
    db "database/sql"

    "github.com/Fs02/go-paranoid"
    "github.com/Fs02/grimoire"
    "github.com/Fs02/grimoire/adapter/sql"
    "github.com/Fs02/grimoire/errors"
    "github.com/Fs02/grimoire/internal"
    "github.com/go-sql-driver/mysql"
)

// Adapter definition for mysql database.
type Adapter struct {
    *sql.Adapter
}

var _ grimoire.Adapter = (*Adapter)(nil)

// Open mysql connection using dsn.
func Open(dsn string) (*Adapter, error) {
    var err error

    adapter := &Adapter{
        Adapter: &sql.Adapter{
            Config: &sql.Config{
                Placeholder:   "?",
                EscapeChar:    "`",
                IncrementFunc: incrementFunc,
                ErrorFunc:     errorFunc,
            },
        },
    }
    adapter.DB, err = db.Open("mysql", dsn)

    return adapter, err
}

func incrementFunc(adapter sql.Adapter) int {
    var variable string
    var increment int
    var err error
    if adapter.Tx != nil {
        err = adapter.Tx.QueryRow("SHOW VARIABLES LIKE 'auto_increment_increment';").Scan(&variable, &increment)
    } else {
        err = adapter.DB.QueryRow("SHOW VARIABLES LIKE 'auto_increment_increment';").Scan(&variable, &increment)
    }
    paranoid.Panic(err, "grimoire: MySQL failed to get auto_increment_increment variable")

    return increment
}

func errorFunc(err error) error {
    if err == nil {
        return nil
    }

    if e, ok := err.(*mysql.MySQLError); ok {
        switch e.Number {
        case 1062:
            return errors.New(e.Message, internal.ExtractString(e.Message, "key '", "'"), errors.UniqueConstraint)
        case 1452:
            return errors.New(e.Message, internal.ExtractString(e.Message, "CONSTRAINT `", "`"), errors.ForeignKeyConstraint)
        }
    }

    return err
}