[log4perl-devel] DBI Appender user suggestion and silent failure issue for mismatched placeholder count

[Adrian C. <ad...@yo...>]

I'm using Log::Log4perl::Appender::DBI and I have a few end-user 
suggestions to make.

I have a significant slab of existing Log::Log4perl code which uses 
variable number of arguments like this:

   Log::Log4perl -> get_logger() -> debug("Parsing start"):
   ...
   Log::Log4perl -> get_logger() -> debug("Done, ", $error_count, " 
errors.");

Using this sort of code with Log::Log4perl::Appender::DBI the way it's 
currently suggested/recommended by the perldoc (prepared statements, '?' 
placeholders and warp_message=0) is presently a poor experience, because 
the number of placeholders is variable.  At the moment this means most 
of my DBI inserts were failing silently and I had to uncomment the 
"warn" on line 138 of Log::Log4perl::Appender::DBI to find out what was 
going wrong (which is rather unfortunate.)

I think it would be better to do something like this as a default in the 
perldoc example (ie. without warp_message, and %m explicitly specified 
as a parameter)

  log4perl.appender.DBLog = Log::Log4perl::Appender::DBI
  log4perl.appender.DBLog.datasource = DBI:mysql:database=log;host=localhost
  log4perl.appender.DBLog.username = user
  log4perl.appender.DBLog.password = pass
  log4perl.appender.DBLog.sql = insert into cc3 (timestamp, severity, 
source, source_line, host, caller, file, message) values 
(unix_timestamp(), ?, ?, ?, ?, ?, ?, ?);
  log4perl.appender.DBLog.params.1 = %p
  log4perl.appender.DBLog.params.2 = %X{source}
  log4perl.appender.DBLog.params.3 = %X{source-line}
  log4perl.appender.DBLog.params.4 = %H
  log4perl.appender.DBLog.params.5 = %M
  log4perl.appender.DBLog.params.6 = +%L %F
  log4perl.appender.DBLog.params.7 = %m
  log4perl.appender.DBLog.usePreparedStmt = 1
  log4perl.appender.DBLog.layout = Log::Log4perl::Layout::NoopLayout

The existing example could then be included in the perldoc under a 
section entitled ("How to get access to individual arguments to debug(), 
warn() etc.")

But it's a great class nevertheless :)

Thanks,
A.

-- 
Adrian Corston
Support Engineer
YourAmigo

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