91 lines
2.1 KiB
Go
91 lines
2.1 KiB
Go
package persistence
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import (
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"fmt"
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"database/sql"
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)
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const ENGINE_DATABASE_VERSION = 0
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type VersionMismatchError struct {
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EngineVersion int
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DatabaseVersion int
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}
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func (e VersionMismatchError) Error() string {
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return fmt.Sprintf(
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`This profile was created with database schema version %d, which is newer than this application's database schema version, %d.
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Please upgrade this application to a newer version to use this profile. Or downgrade the profile's schema version, somehow.`,
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e.DatabaseVersion, e.EngineVersion,
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)
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}
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/**
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* The Nth entry is the migration that moves you from version N to version N+1
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*/
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var MIGRATIONS = []string{
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}
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/**
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* This should only get called on a newly created Profile.
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* Subsequent updates should change the number, not insert a new row.
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*/
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func InitializeDatabaseVersion(db *sql.DB) {
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_, err := db.Exec("insert into database_version (version_number) values (?)", ENGINE_DATABASE_VERSION)
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if err != nil {
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panic(err)
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}
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}
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func (p Profile) GetDatabaseVersion() (int, error) {
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row := p.DB.QueryRow("select version_number from database_version")
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var version int
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err := row.Scan(&version)
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if err != nil {
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return 0, err
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}
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return version, nil
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}
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func (p Profile) check_and_update_version() error {
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version, err := p.GetDatabaseVersion()
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if err != nil {
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return err
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}
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if version > ENGINE_DATABASE_VERSION {
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return VersionMismatchError{ENGINE_DATABASE_VERSION, version}
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}
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if ENGINE_DATABASE_VERSION > version {
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fmt.Printf("Upgrading database from version %d to version %d", version, ENGINE_DATABASE_VERSION)
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return p.UpgradeFromXToY(version, ENGINE_DATABASE_VERSION)
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}
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return nil
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}
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/**
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* Run all the migrations from version X to version Y, and update the `database_version` table's `version_number`
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*/
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func (p Profile) UpgradeFromXToY(x int, y int) error {
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for i := x; i < y; i++ {
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fmt.Println(MIGRATIONS[i])
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_, err := p.DB.Exec(MIGRATIONS[i])
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if err != nil {
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return err
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}
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_, err = p.DB.Exec("update database_version set version_number = ?", i+1)
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if err != nil {
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return err
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}
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fmt.Printf("Now at database schema version %d.\n", i + 1)
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}
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return nil
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}
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