writefreely/migrations/migrations.go

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/*
* Copyright © 2019 A Bunch Tell LLC.
*
* This file is part of WriteFreely.
*
* WriteFreely is free software: you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License, included
* in the LICENSE file in this source code package.
*/
// Package migrations contains database migrations for WriteFreely
package migrations
import (
"database/sql"
"github.com/writeas/web-core/log"
)
// TODO: refactor to use the datastore struct from writefreely pkg
type datastore struct {
*sql.DB
driverName string
}
func NewDatastore(db *sql.DB, dn string) *datastore {
return &datastore{db, dn}
}
// TODO: use these consts from writefreely pkg
const (
driverMySQL = "mysql"
driverSQLite = "sqlite3"
)
type Migration interface {
Description() string
Migrate(db *datastore) error
}
type migration struct {
description string
migrate func(db *datastore) error
}
func New(d string, fn func(db *datastore) error) Migration {
return &migration{d, fn}
}
func (m *migration) Description() string {
return m.description
}
func (m *migration) Migrate(db *datastore) error {
return m.migrate(db)
}
var migrations = []Migration{}
func Migrate(db *datastore) error {
var version int
var err error
if db.tableExists("appmigrations") {
err = db.QueryRow("SELECT MAX(version) FROM appmigrations").Scan(&version)
} else {
log.Info("Initializing appmigrations table...")
version = 0
_, err = db.Exec(`CREATE TABLE appmigrations (
version ` + db.typeInt() + ` NOT NULL,
migrated ` + db.typeDateTime() + ` NOT NULL,
result ` + db.typeText() + ` NOT NULL
) ` + db.engine() + `;`)
if err != nil {
return err
}
}
if len(migrations[version:]) > 0 {
for i, m := range migrations[version:] {
curVer := version + i + 1
log.Info("Migrating to V%d: %s", curVer, m.Description())
err = m.Migrate(db)
if err != nil {
return err
}
// Update migrations table
_, err = db.Exec("INSERT INTO appmigrations (version, migrated, result) VALUES (?, "+db.now()+", ?)", curVer, "")
if err != nil {
return err
}
}
} else {
log.Info("Database up-to-date. No migrations to run.")
}
return nil
}
func (db *datastore) tableExists(t string) bool {
var dummy string
var err error
if db.driverName == driverSQLite {
err = db.QueryRow("SELECT name FROM sqlite_master WHERE type = 'table' AND name = ?", t).Scan(&dummy)
} else {
err = db.QueryRow("SHOW TABLES LIKE ?", t).Scan(&dummy)
}
switch {
case err == sql.ErrNoRows:
return false
case err != nil:
log.Error("Couldn't SHOW TABLES: %v", err)
return false
}
return true
}