This chapter of the tutorial takes a brief look at the primary options
available for troubleshooting Catalyst applications.
+Source code for the tutorial in included in the F</home/catalyst/Final>
+directory of the Tutorial Virtual machine (one subdirectory per
+chapter). There are also instructions for downloading the code in
+L<Catalyst::Manual::Tutorial::01_Intro>.
+
+
Note that when it comes to debugging and troubleshooting, there are two
camps:
=over 4
-=item *
+=item *
Fans of C<log> and C<print> statements embedded in the code.
-=item *
+=item *
Fans of interactive debuggers.
=head1 LOG STATEMENTS
-Folks in the former group can use Catalyst's C<$c-E<gt>log> facility.
+Folks in the former group can use Catalyst's C<< $c->log >> facility.
(See L<Catalyst::Log> for more detail.) For example, if you add the
following code to a controller action method:
$c->log->info("Starting the foreach loop here");
-
+
$c->log->debug("Value of \$id is: ".$id);
Then the Catalyst development server will display your message along
$c->log->error
$c->log->fatal
-You can also use L<Data::Dumper> in both Catalyst code
-(C<use Data::Dumper; $c-E<gt>log-E<gt>debug("\$var is: ".Dumper($var));)>)
-and TT templates (C<[% Dumper.dump(book) %]>.
+You can also use Data::Dumper in both Catalyst code and in TT templates.
+For use in Catalyst code:
+
+ use Data::Dumper;
+ $c->log->debug("\$var is: ".Dumper($c->stash->{something}));
+
+and TT templates:
+
+ [% USE Dumper ; Dumper.dump(c.stash.something) %].
+
+B<NOTE:> Whether you are a logging fanatic or not, we strongly recommend
+that you take advantage of L<Log::Log4perl> or L<Log::Dispatch>. It's
+easy to use L<Catalyst::Log> with either of these and they will provide
+a huge amount of extra functionality that you will want in virtually
+every production application you run or support.
=head1 RUNNING CATALYST UNDER THE PERL DEBUGGER
# 'Context' that's used to 'glue together' the various components
# that make up the application
my ($self, $c) = @_;
-
+
$DB::single=1;
-
+
# Retrieve all of the book records as book model objects and store in the
# stash where they can be accessed by the TT template
$c->stash->{books} = [$c->model('DB::Book')->all];
-
+
# Set the TT template to use. You will almost always want to do this
# in your action methods.
$c->stash->{template} = 'books/list.tt2';
This will start the interactive debugger and produce output similar to:
- $ perl -d script/myapp_server.pl
-
+ $ perl -d script/myapp_server.pl
+
Loading DB routines from perl5db.pl version 1.3
Editor support available.
-
+
Enter h or `h h' for help, or `man perldebug' for more help.
-
+
main::(script/myapp_server.pl:16): my $debug = 0;
-
- DB<1>
+
+ DB<1>
Press the C<c> key and hit C<Enter> to continue executing the Catalyst
development server under the debugger. Although execution speed will be
C<MyApp::Controller::list> method, the console session running the
development server will drop to the Perl debugger prompt:
- MyApp::Controller::Books::list(/home/me/MyApp/script/../lib/MyApp/Controller/Books.pm:48):
+ MyApp::Controller::Books::list(/home/catalyst/MyApp/script/../lib/MyApp/Controller/Books.pm:48):
48: $c->stash->{books} = [$c->model('DB::Book')->all];
-
+
DB<1>
You now have the full Perl debugger at your disposal. First use the
DB<1> n
SELECT me.id, me.title, me.rating, me.created, me.updated FROM book me:
- MyApp::Controller::Books::list(/home/me/MyApp/script/../lib/MyApp/Controller/Books.pm:53):
+ MyApp::Controller::Books::list(/home/catalyst/MyApp/script/../lib/MyApp/Controller/Books.pm:53):
53: $c->stash->{template} = 'books/list.tt2';
-
+
DB<1>
This takes you to the next line of code where the template name is set.
_calculate_score
_collapse_cond
<lines removed for brevity>
-
+
DB<2>
We can also play with the model directly:
=over 4
-=item *
+=item *
Check the version of an installed module:
or die qq(module \"\$m\" is not installed\\n); \
print \$m->VERSION'"
-=item *
+=item *
Check if a modules contains a given method:
Happy debugging.
+
+You can jump to the next chapter of the tutorial here:
+L<Testing|Catalyst::Manual::Tutorial::08_Testing>
+
+
=head1 AUTHOR
Kennedy Clark, C<hkclark@gmail.com>
Feel free to contact the author for any errors or suggestions, but the
best way to report issues is via the CPAN RT Bug system at
-<https://rt.cpan.org/Public/Dist/Display.html?Name=Catalyst-Manual>.
-
-The most recent version of the Catalyst Tutorial can be found at
-L<http://dev.catalyst.perl.org/repos/Catalyst/Catalyst-Manual/5.80/trunk/lib/Catalyst/Manual/Tutorial/>.
+L<https://rt.cpan.org/Public/Dist/Display.html?Name=Catalyst-Manual>.
-Copyright 2006-2010, Kennedy Clark, under the
+Copyright 2006-2011, Kennedy Clark, under the
Creative Commons Attribution Share-Alike License Version 3.0
(L<http://creativecommons.org/licenses/by-sa/3.0/us/>).
projects / catagits/Catalyst-Manual.git / blobdiff