answer/internal/migrations/migrations.go

package migrations

import (
	"context"
	"fmt"

	"github.com/answerdev/answer/internal/base/data"
	"github.com/answerdev/answer/internal/entity"
	"xorm.io/xorm"
)

const minDBVersion = 0 // answer 1.0.0

// Migration describes on migration from lower version to high version
type Migration interface {
	Description() string
	Migrate(*xorm.Engine) error
	ShouldCleanCache() bool
}

type migration struct {
	description      string
	migrate          func(*xorm.Engine) error
	shouldCleanCache bool
}

// Description returns the migration's description
func (m *migration) Description() string {
	return m.description
}

// Migrate executes the migration
func (m *migration) Migrate(x *xorm.Engine) error {
	return m.migrate(x)
}

// ShouldCleanCache should clean the cache
func (m *migration) ShouldCleanCache() bool {
	return m.shouldCleanCache
}

// NewMigration creates a new migration
func NewMigration(desc string, fn func(*xorm.Engine) error, shouldCleanCache bool) Migration {
	return &migration{description: desc, migrate: fn, shouldCleanCache: shouldCleanCache}
}

// Use noopMigration when there is a migration that has been no-oped
var noopMigration = func(_ *xorm.Engine) error { return nil }

var migrations = []Migration{
	// 0->1
	NewMigration("this is first version, no operation", noopMigration, false),
	NewMigration("add user language", addUserLanguage, false),
	NewMigration("add recommend and reserved tag fields", addTagRecommendedAndReserved, false),
	NewMigration("add activity timeline", addActivityTimeline, false),
	NewMigration("add user role", addRoleFeatures, false),
	NewMigration("add theme and private mode", addThemeAndPrivateMode, true),
	NewMigration("add new answer notification", addNewAnswerNotification, true),
	NewMigration("add user pin hide features", addRolePinAndHideFeatures, true),
	NewMigration("update accept answer rank", updateAcceptAnswerRank, true),
	NewMigration("update user pin hide features", updateRolePinAndHideFeatures, true),
}

// GetCurrentDBVersion returns the current db version
func GetCurrentDBVersion(engine *xorm.Engine) (int64, error) {
	if err := engine.Sync(new(entity.Version)); err != nil {
		return -1, fmt.Errorf("sync version failed: %v", err)
	}

	currentVersion := &entity.Version{ID: 1}
	has, err := engine.Get(currentVersion)
	if err != nil {
		return -1, fmt.Errorf("get first version failed: %v", err)
	}
	if !has {
		_, err := engine.InsertOne(&entity.Version{ID: 1, VersionNumber: 0})
		if err != nil {
			return -1, fmt.Errorf("insert first version failed: %v", err)
		}
		return 0, nil
	}
	return currentVersion.VersionNumber, nil
}

// ExpectedVersion returns the expected db version
func ExpectedVersion() int64 {
	return int64(minDBVersion + len(migrations))
}

// Migrate database to current version
func Migrate(dbConf *data.Database, cacheConf *data.CacheConf) error {
	cache, cacheCleanup, err := data.NewCache(cacheConf)
	if err != nil {
		fmt.Println("new check failed:", err.Error())
	}
	engine, err := data.NewDB(false, dbConf)
	if err != nil {
		fmt.Println("new database failed: ", err.Error())
		return err
	}

	currentDBVersion, err := GetCurrentDBVersion(engine)
	if err != nil {
		return err
	}
	expectedVersion := ExpectedVersion()

	for currentDBVersion < expectedVersion {
		fmt.Printf("[migrate] current db version is %d, try to migrate version %d, latest version is %d\n",
			currentDBVersion, currentDBVersion+1, expectedVersion)
		migrationFunc := migrations[currentDBVersion]
		fmt.Printf("[migrate] try to migrate db version %d, description: %s\n", currentDBVersion+1, migrationFunc.Description())
		if err := migrationFunc.Migrate(engine); err != nil {
			fmt.Printf("[migrate] migrate to db version %d failed: %s\n", currentDBVersion+1, err.Error())
			return err
		}
		if migrationFunc.ShouldCleanCache() {
			if err := cache.Flush(context.Background()); err != nil {
				fmt.Printf("[migrate] flush cache failed: %s\n", err.Error())
			}
		}
		fmt.Printf("[migrate] migrate to db version %d success\n", currentDBVersion+1)
		if _, err := engine.Update(&entity.Version{ID: 1, VersionNumber: currentDBVersion + 1}); err != nil {
			fmt.Printf("[migrate] migrate to db version %d, update failed: %s", currentDBVersion+1, err.Error())
			return err
		}
		currentDBVersion++
	}
	if cache != nil {
		cacheCleanup()
	}
	return nil
}