#475: Improve error message for unsupported named parameters

[JKDingwall]

Previously just 'Illegal parameter number' was logged, make this a more helpful message.

[25-05-06 20:46:04.2629] Slim::Schema::Storage::throw_exception (122) Error: DBI Exception: DBD::mysql::st bind_param failed: named parameters are unsupported: :album [for Statement "
                                        SELECT contributor_album.role AS role, contributors.name AS name, contributors.id AS id
                                        FROM contributor_album
                                        JOIN contributors ON contributors.id = contributor_album.contributor
                                        WHERE contributor_album.album = :album
                                        AND contributor_album.role IN (5,1)
                                        ORDER BY contributor_album.role, contributors.namesort
                                "]

[dveeden]

This probably need a few doc/pod updates and one or more tests.

[JKDingwall]

This probably need a few doc/pod updates and one or more tests.

@dveeden This is my first attempt working on a perl module so if you don't mind a couple of questions...

1. doc/pod: would you just like a mention that named parameters are not supported and indicate what error message would be reported if they are used?

2. tests: would one new test that asserts the expected message is emitted if a named parameter is used be sufficient? would it be best in a new test file or as an addition to an existing one?

I couldn't understand why "looks_like_number(1)" failed here https://github.com/perl5-dbi/DBD-mysql/actions/runs/14923375602/job/41923094232#step:10:49 but I changed the code to put the new check under the failure which was originally being triggered. When I dpkg-buildpackage -b all tests pass with MySQL.

[dveeden]

@JKDingwall

1. Yes just check the current docs and update if needed. Preferably with some suggestion about what to use instead. If you think no updates are needed than that might be ok.
2. Yes. Probably a new test file to test that this does work as intended. If there is a file that already has something very similar that including this in that file would also be fine.

Also note that MySQL might make it easier to add named attributes in the future:

• https://dev.mysql.com/doc/refman/9.3/en/query-attributes.html
• https://dev.mysql.com/doc/c-api/9.3/en/mysql-bind-param.html
• https://databaseblog.myname.nl/2025/02/the-potential-of-query-attributes-in.html
• https://archive.fosdem.org/2021/schedule/event/mysql_protocl/

[JKDingwall]

@dveeden I've added a new test that the expected error message is reported if bind_param(':name', 1) is called. I've also added a couple of sentences to the documentation that named parameters are not supported. Please let me know you'd like any changes made, thanks!

This is the output from the test:

t/45bindnamedparam_error.t ....................
1..11
ok 1
ok 2
ok 3 - create table dbd_mysql_t45bindnamedparam
ok 4 - insert into dbd_mysql_t45bindnamedparam (null, 1)
ok 5
ok 6 - $rows->[0][1] == 1
ok 7
ok 8
ok 9 - bind_param reports exepcted error with named parameter
ok 10
ok 11
Argument ":num" isn't numeric in subroutine entry at t/45bindnamedparam.t line 50.
DBD::mysql::st bind_param failed: named parameters are unsupported: :num at t/45bindnamedparam.t line 50.
ok

I had seen the documentation about named attributes but after some research I realised that its actually a bit misleading. The feature provides a way to annotate a query with, for example, the name of script which invoked the query.

• https://stackoverflow.com/questions/77626696/understanding-mysql-stmt-bind-named-param-mysql-c-api
• https://mysql.wisborg.dk/2021/02/02/mysql-query-attributes/

[dveeden]

DBD::mysql needs MySQL 8.0 or newer, so this shouldn't be needed. But on the other hand... it doesn't hurt either.

[dveeden]

Is there a test for this error?

What if there are multiple params. Does it indicate which one is the issue? Could/should it?

[dveeden]

Suggested change

	"named parameters are unsupported" error is reported.
	`JW_ERR_ILLEGAL_PARAM_NUM` with a message of "named parameters are unsupported" error is reported.

btw. I think JW stands for Jim Winstead. See git log