Merge pull request #2115 from ninedraft/sql-err-no-rows

Use sql.ErrNoRows as value for pgx.ErrNoRows

Author: jackc

conn.go

@@ -3,6 +3,7 @@ package pgx
 import (
 	"context"
 	"crypto/sha256"
+	"database/sql"
 	"encoding/hex"
 	"errors"
 	"fmt"
@@ -102,11 +103,27 @@ func (ident Identifier) Sanitize() string {
 
 var (
 	// ErrNoRows occurs when rows are expected but none are returned.
-	ErrNoRows = errors.New("no rows in result set")
+	ErrNoRows = newProxyErr(sql.ErrNoRows, "no rows in result set")
 	// ErrTooManyRows occurs when more rows than expected are returned.
 	ErrTooManyRows = errors.New("too many rows in result set")
 )
 
+func newProxyErr(background error, msg string) error {
+	return &proxyError{
+		msg:        msg,
+		background: background,
+	}
+}
+
+type proxyError struct {
+	msg        string
+	background error
+}
+
+func (err *proxyError) Error() string { return err.msg }
+
+func (err *proxyError) Unwrap() error { return err.background }
+
 var (
 	errDisabledStatementCache   = fmt.Errorf("cannot use QueryExecModeCacheStatement with disabled statement cache")
 	errDisabledDescriptionCache = fmt.Errorf("cannot use QueryExecModeCacheDescribe with disabled description cache")

conn_test.go

@@ -3,6 +3,7 @@ package pgx_test
 import (
 	"bytes"
 	"context"
+	"database/sql"
 	"os"
 	"strings"
 	"sync"
@@ -1408,3 +1409,13 @@ func TestConnDeallocateInvalidatedCachedStatementsInTransactionWithBatch(t *test
 
 	ensureConnValid(t, conn)
 }
+
+func TestErrNoRows(t *testing.T) {
+	t.Parallel()
+
+	// ensure we preserve old error message
+	require.Equal(t, "no rows in result set", pgx.ErrNoRows.Error())
+
+	require.ErrorIs(t, pgx.ErrNoRows, sql.ErrNoRows, "pgx.ErrNowRows must match sql.ErrNoRows")
+	require.ErrorIs(t, pgx.ErrNoRows, pgx.ErrNoRows, "sql.ErrNowRows must match pgx.ErrNoRows")
+}