108 lines
2.5 KiB
Go
108 lines
2.5 KiB
Go
// Package migrate allows you to update your database from your application
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package migrate
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import (
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"database/sql"
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"errors"
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"fmt"
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"strconv"
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)
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// Options contains all settings
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type Options struct {
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TableName string // Name used for version info table; defaults to DefaultTableName if not set
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Schema string // Schema used for version info table; In PostgreSQL the current schema is changed to the one specified here
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AssetPrefix string
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}
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// DefaultTableName is the name used when no TableName is specified in Options
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const DefaultTableName = `version`
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// ErrUpdatesMissing indicates an update is missing, making it impossible to execute the migration
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var ErrUpdatesMissing = errors.New(`Missing migration files`)
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const fileFormat = `%04d.sql`
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// AssetFunc is a function that returns the data for the given name
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type AssetFunc func(string) ([]byte, error)
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// Migrate executes migrations to get to the desired version
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// Downgrading is not supported as it could result in data loss
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func Migrate(db *sql.DB, version int, o Options, asset AssetFunc) error {
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dbType := getDbType(db)
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if o.TableName == `` {
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o.TableName = DefaultTableName
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}
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var err error
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searchPath := `public`
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tx, err := db.Begin()
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if err != nil {
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return err
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}
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defer tx.Rollback()
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if o.Schema != `` {
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err = createSchemaIfNotExists(tx, o.Schema)
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if err != nil {
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return err
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}
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if dbType == `pq` {
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_ = tx.QueryRow(`SHOW search_path`).Scan(&searchPath)
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_, err = tx.Exec(`SET search_path TO ` + o.Schema)
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if err != nil {
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return err
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}
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}
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}
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versionTable, err := createTableIfNotExists(tx, o.Schema, o.TableName)
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if err != nil {
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return err
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}
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row := tx.QueryRow(`SELECT version FROM ` + versionTable + ` ORDER BY Version DESC`)
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var v int
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err = row.Scan(&v)
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if err != sql.ErrNoRows && err != nil {
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return err
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}
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for i := v + 1; i <= version; i++ {
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fileName := fmt.Sprintf(o.AssetPrefix+fileFormat, i)
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errorf := func(e error) error { return fmt.Errorf(`migration "%s" failed: %w`, fileName, e) }
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script, err := asset(fileName)
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if err != nil {
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return errorf(ErrUpdatesMissing)
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}
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_, err = tx.Exec(string(script))
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if err != nil {
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return errorf(err)
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}
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_, err = tx.Exec(`INSERT INTO ` + versionTable + ` (version) VALUES (` + strconv.Itoa(i) + `)`)
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if err != nil {
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return errorf(err)
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}
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}
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if dbType == `pq` && o.Schema != `` {
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_, err = tx.Exec(`SET search_path TO ` + searchPath)
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if err != nil {
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return err
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}
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}
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err = tx.Commit()
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if err != nil {
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return err
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}
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return nil
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}
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