113 lines
2.4 KiB
Go
113 lines
2.4 KiB
Go
package migrate
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import (
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"database/sql"
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"fmt"
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"strings"
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"time"
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)
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// EnsureSchema applies all "up" migrations when the database has no tables.
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func EnsureSchema(db *sql.DB, dir string) error {
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if err := ensureSchemaMigrations(db); err != nil {
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return err
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}
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empty, err := isDatabaseEmpty(db)
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if err != nil {
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return err
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}
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runner := Runner{Dir: dir}
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migrations, err := runner.Load(Up)
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if err != nil {
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return err
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}
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if empty {
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for _, migration := range migrations {
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if err := execStatements(db, migration.SQL); err != nil {
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return fmt.Errorf("apply %s: %w", migration.Name, err)
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}
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if err := recordMigration(db, migration.Name); err != nil {
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return err
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}
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}
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return nil
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}
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applied, err := loadAppliedMigrations(db)
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if err != nil {
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return err
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}
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for _, migration := range migrations {
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if applied[migration.Name] {
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continue
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}
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if err := execStatements(db, migration.SQL); err != nil {
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return fmt.Errorf("apply %s: %w", migration.Name, err)
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}
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if err := recordMigration(db, migration.Name); err != nil {
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return err
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}
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}
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return nil
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}
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func isDatabaseEmpty(db *sql.DB) (bool, error) {
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var count int
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if err := db.QueryRow(`SELECT COUNT(*) FROM information_schema.tables WHERE table_schema = DATABASE()`).Scan(&count); err != nil {
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return false, err
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}
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return count == 0, nil
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}
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func execStatements(db *sql.DB, sqlText string) error {
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statements := strings.Split(sqlText, ";")
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for _, stmt := range statements {
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stmt = strings.TrimSpace(stmt)
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if stmt == "" {
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continue
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}
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if _, err := db.Exec(stmt); err != nil {
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return err
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}
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}
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return nil
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}
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func ensureSchemaMigrations(db *sql.DB) error {
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_, err := db.Exec(`CREATE TABLE IF NOT EXISTS schema_migrations (
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id BIGINT PRIMARY KEY AUTO_INCREMENT,
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name VARCHAR(255) NOT NULL UNIQUE,
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applied_at TIMESTAMP NOT NULL
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)`)
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return err
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}
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func loadAppliedMigrations(db *sql.DB) (map[string]bool, error) {
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rows, err := db.Query(`SELECT name FROM schema_migrations`)
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if err != nil {
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return nil, err
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}
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defer rows.Close()
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applied := map[string]bool{}
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for rows.Next() {
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var name string
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if err := rows.Scan(&name); err != nil {
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return nil, err
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}
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applied[name] = true
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}
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if err := rows.Err(); err != nil {
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return nil, err
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}
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return applied, nil
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}
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func recordMigration(db *sql.DB, name string) error {
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_, err := db.Exec(`INSERT INTO schema_migrations (name, applied_at) VALUES (?, ?)`, name, time.Now().UTC())
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return err
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}
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