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rows.go
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rows.go
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package pgx
import (
"context"
"errors"
"fmt"
"time"
"github.com/jackc/pgconn"
"github.com/jackc/pgproto3/v2"
"github.com/jackc/pgtype"
)
// Rows is the result set returned from *Conn.Query. Rows must be closed before
// the *Conn can be used again. Rows are closed by explicitly calling Close(),
// calling Next() until it returns false, or when a fatal error occurs.
//
// Once a Rows is closed the only methods that may be called are Close(), Err(), and CommandTag().
//
// Rows is an interface instead of a struct to allow tests to mock Query. However,
// adding a method to an interface is technically a breaking change. Because of this
// the Rows interface is partially excluded from semantic version requirements.
// Methods will not be removed or changed, but new methods may be added.
type Rows interface {
// Close closes the rows, making the connection ready for use again. It is safe
// to call Close after rows is already closed.
Close()
// Err returns any error that occurred while reading.
Err() error
// CommandTag returns the command tag from this query. It is only available after Rows is closed.
CommandTag() pgconn.CommandTag
FieldDescriptions() []pgproto3.FieldDescription
// Next prepares the next row for reading. It returns true if there is another
// row and false if no more rows are available. It automatically closes rows
// when all rows are read.
Next() bool
// Scan reads the values from the current row into dest values positionally.
// dest can include pointers to core types, values implementing the Scanner
// interface, and nil. nil will skip the value entirely. It is an error to
// call Scan without first calling Next() and checking that it returned true.
Scan(dest ...interface{}) error
// Values returns the decoded row values. As with Scan(), it is an error to
// call Values without first calling Next() and checking that it returned
// true.
Values() ([]interface{}, error)
// RawValues returns the unparsed bytes of the row values. The returned [][]byte is only valid until the next Next
// call or the Rows is closed. However, the underlying byte data is safe to retain a reference to and mutate.
RawValues() [][]byte
}
// Row is a convenience wrapper over Rows that is returned by QueryRow.
//
// Row is an interface instead of a struct to allow tests to mock QueryRow. However,
// adding a method to an interface is technically a breaking change. Because of this
// the Row interface is partially excluded from semantic version requirements.
// Methods will not be removed or changed, but new methods may be added.
type Row interface {
// Scan works the same as Rows. with the following exceptions. If no
// rows were found it returns ErrNoRows. If multiple rows are returned it
// ignores all but the first.
Scan(dest ...interface{}) error
}
// connRow implements the Row interface for Conn.QueryRow.
type connRow connRows
func (r *connRow) Scan(dest ...interface{}) (err error) {
rows := (*connRows)(r)
if rows.Err() != nil {
return rows.Err()
}
if !rows.Next() {
if rows.Err() == nil {
return ErrNoRows
}
return rows.Err()
}
rows.Scan(dest...)
rows.Close()
return rows.Err()
}
type rowLog interface {
shouldLog(lvl LogLevel) bool
log(ctx context.Context, lvl LogLevel, msg string, data map[string]interface{})
}
// connRows implements the Rows interface for Conn.Query.
type connRows struct {
ctx context.Context
logger rowLog
connInfo *pgtype.ConnInfo
values [][]byte
rowCount int
err error
commandTag pgconn.CommandTag
startTime time.Time
sql string
args []interface{}
closed bool
conn *Conn
resultReader *pgconn.ResultReader
multiResultReader *pgconn.MultiResultReader
scanPlans []pgtype.ScanPlan
}
func (rows *connRows) FieldDescriptions() []pgproto3.FieldDescription {
return rows.resultReader.FieldDescriptions()
}
func (rows *connRows) Close() {
if rows.closed {
return
}
rows.closed = true
if rows.resultReader != nil {
var closeErr error
rows.commandTag, closeErr = rows.resultReader.Close()
if rows.err == nil {
rows.err = closeErr
}
}
if rows.multiResultReader != nil {
closeErr := rows.multiResultReader.Close()
if rows.err == nil {
rows.err = closeErr
}
}
if rows.logger != nil {
endTime := time.Now()
if rows.err == nil {
if rows.logger.shouldLog(LogLevelInfo) {
rows.logger.log(rows.ctx, LogLevelInfo, "Query", map[string]interface{}{"sql": rows.sql, "args": logQueryArgs(rows.args), "time": endTime.Sub(rows.startTime), "rowCount": rows.rowCount})
}
} else {
if rows.logger.shouldLog(LogLevelError) {
rows.logger.log(rows.ctx, LogLevelError, "Query", map[string]interface{}{"err": rows.err, "sql": rows.sql, "time": endTime.Sub(rows.startTime), "args": logQueryArgs(rows.args)})
}
if rows.err != nil && rows.conn.stmtcache != nil {
rows.conn.stmtcache.StatementErrored(rows.sql, rows.err)
}
}
}
}
func (rows *connRows) CommandTag() pgconn.CommandTag {
return rows.commandTag
}
func (rows *connRows) Err() error {
return rows.err
}
// fatal signals an error occurred after the query was sent to the server. It
// closes the rows automatically.
func (rows *connRows) fatal(err error) {
if rows.err != nil {
return
}
rows.err = err
rows.Close()
}
func (rows *connRows) Next() bool {
if rows.closed {
return false
}
if rows.resultReader.NextRow() {
rows.rowCount++
rows.values = rows.resultReader.Values()
return true
} else {
rows.Close()
return false
}
}
func (rows *connRows) Scan(dest ...interface{}) error {
ci := rows.connInfo
fieldDescriptions := rows.FieldDescriptions()
values := rows.values
if len(fieldDescriptions) != len(values) {
err := fmt.Errorf("number of field descriptions must equal number of values, got %d and %d", len(fieldDescriptions), len(values))
rows.fatal(err)
return err
}
if len(fieldDescriptions) != len(dest) {
err := fmt.Errorf("number of field descriptions must equal number of destinations, got %d and %d", len(fieldDescriptions), len(dest))
rows.fatal(err)
return err
}
if rows.scanPlans == nil {
rows.scanPlans = make([]pgtype.ScanPlan, len(values))
for i := range dest {
rows.scanPlans[i] = ci.PlanScan(fieldDescriptions[i].DataTypeOID, fieldDescriptions[i].Format, dest[i])
}
}
for i, dst := range dest {
if dst == nil {
continue
}
err := rows.scanPlans[i].Scan(ci, fieldDescriptions[i].DataTypeOID, fieldDescriptions[i].Format, values[i], dst)
if err != nil {
err = ScanArgError{ColumnIndex: i, Err: err}
rows.fatal(err)
return err
}
}
return nil
}
func (rows *connRows) Values() ([]interface{}, error) {
if rows.closed {
return nil, errors.New("rows is closed")
}
values := make([]interface{}, 0, len(rows.FieldDescriptions()))
for i := range rows.FieldDescriptions() {
buf := rows.values[i]
fd := &rows.FieldDescriptions()[i]
if buf == nil {
values = append(values, nil)
continue
}
if dt, ok := rows.connInfo.DataTypeForOID(fd.DataTypeOID); ok {
value := dt.Value
switch fd.Format {
case TextFormatCode:
decoder, ok := value.(pgtype.TextDecoder)
if !ok {
decoder = &pgtype.GenericText{}
}
err := decoder.DecodeText(rows.connInfo, buf)
if err != nil {
rows.fatal(err)
}
values = append(values, decoder.(pgtype.Value).Get())
case BinaryFormatCode:
decoder, ok := value.(pgtype.BinaryDecoder)
if !ok {
decoder = &pgtype.GenericBinary{}
}
err := decoder.DecodeBinary(rows.connInfo, buf)
if err != nil {
rows.fatal(err)
}
values = append(values, value.Get())
default:
rows.fatal(errors.New("Unknown format code"))
}
} else {
switch fd.Format {
case TextFormatCode:
decoder := &pgtype.GenericText{}
err := decoder.DecodeText(rows.connInfo, buf)
if err != nil {
rows.fatal(err)
}
values = append(values, decoder.Get())
case BinaryFormatCode:
decoder := &pgtype.GenericBinary{}
err := decoder.DecodeBinary(rows.connInfo, buf)
if err != nil {
rows.fatal(err)
}
values = append(values, decoder.Get())
default:
rows.fatal(errors.New("Unknown format code"))
}
}
if rows.Err() != nil {
return nil, rows.Err()
}
}
return values, rows.Err()
}
func (rows *connRows) RawValues() [][]byte {
return rows.values
}
type ScanArgError struct {
ColumnIndex int
Err error
}
func (e ScanArgError) Error() string {
return fmt.Sprintf("can't scan into dest[%d]: %v", e.ColumnIndex, e.Err)
}
func (e ScanArgError) Unwrap() error {
return e.Err
}
// ScanRow decodes raw row data into dest. It can be used to scan rows read from the lower level pgconn interface.
//
// connInfo - OID to Go type mapping.
// fieldDescriptions - OID and format of values
// values - the raw data as returned from the PostgreSQL server
// dest - the destination that values will be decoded into
func ScanRow(connInfo *pgtype.ConnInfo, fieldDescriptions []pgproto3.FieldDescription, values [][]byte, dest ...interface{}) error {
if len(fieldDescriptions) != len(values) {
return fmt.Errorf("number of field descriptions must equal number of values, got %d and %d", len(fieldDescriptions), len(values))
}
if len(fieldDescriptions) != len(dest) {
return fmt.Errorf("number of field descriptions must equal number of destinations, got %d and %d", len(fieldDescriptions), len(dest))
}
for i, d := range dest {
if d == nil {
continue
}
err := connInfo.Scan(fieldDescriptions[i].DataTypeOID, fieldDescriptions[i].Format, values[i], d)
if err != nil {
return ScanArgError{ColumnIndex: i, Err: err}
}
}
return nil
}