135 lines
3.5 KiB
Go
135 lines
3.5 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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_ "github.com/mattn/go-sqlite3"
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"github.com/dchest/uniuri"
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)
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type SQLiteDriver MigrationDriver
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func SQLite(tx *sql.Tx) Operation {
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return &SQLiteDriver{Tx: tx}
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}
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func (s *SQLiteDriver) CreateTable(tableName string, args []string) (sql.Result, error) {
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return s.Tx.Exec(fmt.Sprintf("CREATE TABLE %s (%s);", tableName, strings.Join(args, ", ")))
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}
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func (s *SQLiteDriver) RenameTable(tableName, newName string) (sql.Result, error) {
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return s.Tx.Exec(fmt.Sprintf("ALTER TABLE %s RENAME TO %s;", tableName, newName))
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}
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func (s *SQLiteDriver) DropTable(tableName string) (sql.Result, error) {
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return s.Tx.Exec(fmt.Sprintf("DROP TABLE IF EXISTS %s;", tableName))
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}
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func (s *SQLiteDriver) AddColumn(tableName, columnSpec string) (sql.Result, error) {
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return s.Tx.Exec(fmt.Sprintf("ALTER TABLE %s ADD COLUMN %s;", tableName, columnSpec))
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}
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func (s *SQLiteDriver) DropColumns(tableName string, columnsToDrop []string) (sql.Result, error) {
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if len(columnsToDrop) == 0 {
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return nil, fmt.Errorf("No columns to drop.")
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}
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sql, err := s.getDDLFromTable(tableName)
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if err != nil {
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return nil, err
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}
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columns, err := fetchColumns(sql)
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if err != nil {
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return nil, err
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}
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columnNames := selectName(columns)
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preparedColumns := make([]string, len(columnNames)-len(columnsToDrop))
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for k, column := range columnNames {
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listed := false
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for _, dropped := range columnsToDrop {
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if column == dropped {
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listed = true
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break
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}
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}
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if !listed {
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preparedColumns = append(preparedColumns, columns[k])
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}
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}
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if len(preparedColumns) == 0 {
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return nil, fmt.Errorf("No columns match, drops nothing.")
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}
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// Rename old table, here's our proxy
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proxyName := fmt.Sprintf("%s_%s", tableName, uniuri.NewLen(16))
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if result, err := s.RenameTable(tableName, proxyName); err != nil {
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return result, err
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}
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// Recreate table with dropped columns omitted
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if result, err := s.CreateTable(tableName, preparedColumns); err != nil {
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return result, err
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}
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// Move data from old table
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if result, err := s.Tx.Exec(fmt.Sprintf("INSERT INTO %s SELECT %s FROM %s;", tableName,
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strings.Join(selectName(preparedColumns), ", "), proxyName)); err != nil {
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return result, err
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}
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// Clean up proxy table
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return s.Tx.Exec(fmt.Sprintf("DROP TABLE %s;", proxyName))
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}
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func (s *SQLiteDriver) RenameColumns(tableName string, columnChanges map[string]string) (sql.Result, error) {
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sql, err := s.getDDLFromTable(tableName)
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if err != nil {
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return nil, err
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}
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columns, err := fetchColumns(sql)
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if err != nil {
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return nil, err
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}
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oldColumns := make([]string, len(columnChanges))
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newColumns := make([]string, len(columnChanges))
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for k, column := range selectName(columns) {
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for Old, New := range columnChanges {
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if column == Old {
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columnToAdd := strings.Replace(columns[k], Old, New, 1)
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if results, err := s.AddColumn(tableName, columnToAdd); err != nil {
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return results, err
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}
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oldColumns = append(oldColumns, Old)
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newColumns = append(newColumns, New)
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break
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}
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}
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}
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statement := fmt.Sprintf("UPDATE %s SET %s;", tableName, setForUpdate(oldColumns, newColumns))
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if results, err := s.Tx.Exec(statement); err != nil {
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return results, err
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}
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return s.DropColumns(tableName, oldColumns)
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}
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func (s *SQLiteDriver) getDDLFromTable(tableName string) (string, error) {
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var sql string
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query := `SELECT sql FROM sqlite_master WHERE type='table' and name='?';`
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err := s.Tx.QueryRow(query, tableName).Scan(&sql)
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if err != nil {
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return "", err
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}
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return sql, nil
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}
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