database/sql: add method Err on sql.Row

The Row.Err method is intended to assist wrapping sql.DB.
Because sql.Row is a struct with private fields,
a wrapper in an existing code base cannot easily provide users
with a different implementation without large rewrites.
Adding this method allows query level errors to be handled
centrally.

Fixes #35804

Change-Id: I94e6329de89a7ee1284ce9ef76af4363d2d081f9
Reviewed-on: https://go-review.googlesource.com/c/go/+/214317
Reviewed-by: Daniel Theophanes <kardianos@gmail.com>
Run-TryBot: Daniel Theophanes <kardianos@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>

1 files changed, 8 insertions, 0 deletions

diff --git a/src/database/sql/sql.go b/src/database/sql/sql.go
index 1bf3731b00..95906b1318 100644
--- a/src/database/sql/sql.go
+++ b/src/database/sql/sql.go
@@ -3174,6 +3174,14 @@ func (r *Row) Scan(dest ...interface{}) error {
 	return r.rows.Close()
 }
 
+// Err provides a way for wrapping packages to check for
+// query errors without calling Scan.
+// Err returns the error, if any, that was encountered while running the query.
+// If this error is not nil, this error will also be returned from Scan.
+func (r *Row) Err() error {
+	return r.err
+}
+
 // A Result summarizes an executed SQL command.
 type Result interface {
 	// LastInsertId returns the integer generated by the database