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tx.go
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tx.go
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package pg
import (
"io"
"os"
"gopkg.in/pg.v4/internal/pool"
"gopkg.in/pg.v4/orm"
"gopkg.in/pg.v4/types"
)
// When true Tx does not issue BEGIN, COMMIT, and ROLLBACK.
// It is primarily useful for testing and can be enabled with
// GO_PG_NO_TX environment variable.
var noTx bool
func init() {
noTx = os.Getenv("GO_PG_NO_TX") != ""
}
// Tx is an in-progress database transaction.
//
// A transaction must end with a call to Commit or Rollback.
//
// After a call to Commit or Rollback, all operations on the transaction fail
// with ErrTxDone.
//
// The statements prepared for a transaction by calling the transaction's
// Prepare or Stmt methods are closed by the call to Commit or Rollback.
type Tx struct {
db *DB
_cn *pool.Conn
stmts []*Stmt
}
// Begin starts a transaction. Most callers should use RunInTransaction instead.
func (db *DB) Begin() (*Tx, error) {
cn, err := db.conn()
if err != nil {
return nil, err
}
tx := &Tx{
db: db,
_cn: cn,
}
if !noTx {
if _, err := tx.Exec("BEGIN"); err != nil {
tx.close(err)
return nil, err
}
}
return tx, nil
}
// RunInTransaction runs a function in a transaction. If function
// returns an error transaction is rollbacked, otherwise transaction
// is committed.
func (db *DB) RunInTransaction(fn func(*Tx) error) error {
tx, err := db.Begin()
if err != nil {
return err
}
if err := fn(tx); err != nil {
tx.Rollback()
return err
}
return tx.Commit()
}
func (tx *Tx) conn() (*pool.Conn, error) {
if tx._cn == nil {
return nil, errTxDone
}
tx._cn.SetReadTimeout(tx.db.opt.ReadTimeout)
tx._cn.SetWriteTimeout(tx.db.opt.WriteTimeout)
return tx._cn, nil
}
// Stmt returns a transaction-specific prepared statement from an existing statement.
func (tx *Tx) Stmt(stmt *Stmt) *Stmt {
stmt, err := tx.Prepare(stmt.q)
if err != nil {
return &Stmt{stickyErr: err}
}
return stmt
}
// Prepare creates a prepared statement for use within a transaction.
//
// The returned statement operates within the transaction and can no longer
// be used once the transaction has been committed or rolled back.
//
// To use an existing prepared statement on this transaction, see Tx.Stmt.
func (tx *Tx) Prepare(q string) (*Stmt, error) {
cn, err := tx.conn()
if err != nil {
return nil, err
}
stmt, err := prepare(tx.db, cn, q)
if err != nil {
return nil, err
}
stmt.inTx = true
tx.stmts = append(tx.stmts, stmt)
return stmt, nil
}
// Exec executes a query with the given parameters in a transaction.
func (tx *Tx) Exec(query interface{}, params ...interface{}) (*types.Result, error) {
cn, err := tx.conn()
if err != nil {
return nil, err
}
res, err := simpleQuery(cn, query, params...)
if err != nil {
return nil, err
}
return res, nil
}
// ExecOne acts like Exec, but query must affect only one row. It
// returns ErrNoRows error when query returns zero rows or
// ErrMultiRows when query returns multiple rows.
func (tx *Tx) ExecOne(query interface{}, params ...interface{}) (*types.Result, error) {
res, err := tx.Exec(query, params...)
if err != nil {
return nil, err
}
return assertOneAffected(res)
}
// Query executes a query with the given parameters in a transaction.
func (tx *Tx) Query(model interface{}, query interface{}, params ...interface{}) (*types.Result, error) {
cn, err := tx.conn()
if err != nil {
return nil, err
}
res, err := simpleQueryData(cn, model, query, params...)
if err != nil {
return nil, err
}
return res, nil
}
// QueryOne acts like Query, but query must return only one row. It
// returns ErrNoRows error when query returns zero rows or
// ErrMultiRows when query returns multiple rows.
func (tx *Tx) QueryOne(model interface{}, query interface{}, params ...interface{}) (*types.Result, error) {
mod, err := newSingleModel(model)
if err != nil {
return nil, err
}
res, err := tx.Query(mod, query, params...)
if err != nil {
return nil, err
}
return assertOneAffected(res)
}
// Model returns new query for the model.
func (tx *Tx) Model(model interface{}) *orm.Query {
return orm.NewQuery(tx, model)
}
// Select selects the model by primary key.
func (tx *Tx) Select(model interface{}) error {
return orm.Select(tx, model)
}
// Create inserts the model updating primary keys if they are empty.
func (tx *Tx) Create(model interface{}) error {
return orm.Create(tx, model)
}
// Update updates the model by primary key.
func (tx *Tx) Update(model interface{}) error {
return orm.Update(tx, model)
}
// Delete deletes the model by primary key.
func (tx *Tx) Delete(model interface{}) error {
return orm.Delete(tx, model)
}
// Commit commits the transaction.
func (tx *Tx) Commit() (err error) {
if !noTx {
_, err = tx.Exec("COMMIT")
}
tx.close(err)
return err
}
// Rollback aborts the transaction.
func (tx *Tx) Rollback() (err error) {
if !noTx {
_, err = tx.Exec("ROLLBACK")
}
tx.close(err)
return err
}
func (tx *Tx) FormatQuery(dst []byte, query string, params ...interface{}) []byte {
return tx.db.FormatQuery(dst, query, params...)
}
func (tx *Tx) close(err error) error {
if tx._cn == nil {
return errTxDone
}
for _, stmt := range tx.stmts {
_ = stmt.Close()
}
tx.stmts = nil
err = tx.db.freeConn(tx._cn, err)
tx._cn = nil
return err
}
// CopyFrom copies data from reader to a table.
func (tx *Tx) CopyFrom(r io.Reader, query string, params ...interface{}) (*types.Result, error) {
cn, err := tx.conn()
if err != nil {
return nil, err
}
res, err := copyFrom(cn, r, query, params...)
if err != nil {
return nil, err
}
return res, nil
}