Method Prepare

pgconn/pgconn.go:950–1008

Prepare creates a prepared statement. If the name is empty, the anonymous prepared statement will be used. This allows Prepare to also to describe statements without creating a server-side prepared statement. Prepare does not send a PREPARE statement to the server. It uses the PostgreSQL Parse and

(ctx context.Context, name, sql string, paramOIDs []uint32)

// case, the returned error will be an error where errors.As with a *PrepareError succeeds and the *PrepareError has
// ParseComplete set to true.
func (pgConn *PgConn) Prepare(ctx context.Context, name, sql string, paramOIDs []uint32) (*StatementDescription, error) {
	if err := pgConn.lock(); err != nil {
		return nil, err
	}
	defer pgConn.unlock()

	if ctx != context.Background() {
		select {
		case <-ctx.Done():
			return nil, newContextAlreadyDoneError(ctx)
		default:
		}
		pgConn.contextWatcher.Watch(ctx)
		defer pgConn.contextWatcher.Unwatch()
	}

	pgConn.frontend.SendParse(&pgproto3.Parse{Name: name, Query: sql, ParameterOIDs: paramOIDs})
	pgConn.frontend.SendDescribe(&pgproto3.Describe{ObjectType: 'S', Name: name})
	pgConn.frontend.SendSync(&pgproto3.Sync{})
	err := pgConn.flushWithPotentialWriteReadDeadlock()
	if err != nil {
		pgConn.asyncClose()
		return nil, err
	}

	psd := &StatementDescription{Name: name, SQL: sql}

	var ParseComplete bool
	var pgErr *PgError

readloop:
	for {
		msg, err := pgConn.receiveMessage()
		if err != nil {
			pgConn.asyncClose()
			return nil, normalizeTimeoutError(ctx, err)
		}

		switch msg := msg.(type) {
		case *pgproto3.ParseComplete:
			ParseComplete = true
		case *pgproto3.ParameterDescription:
			psd.ParamOIDs = make([]uint32, len(msg.ParameterOIDs))
			copy(psd.ParamOIDs, msg.ParameterOIDs)
		case *pgproto3.RowDescription:
			psd.Fields = make([]FieldDescription, len(msg.Fields))
			convertRowDescription(psd.Fields, msg)
		case *pgproto3.ErrorResponse:
			pgErr = ErrorResponseToPgError(msg)
		case *pgproto3.ReadyForQuery:
			break readloop
		}
	}

	if pgErr != nil {
		return nil, &PrepareError{err: pgErr, ParseComplete: ParseComplete}
	}
	return psd, nil