1LWP::ConsoleLogger(3) User Contributed Perl DocumentationLWP::ConsoleLogger(3)
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NAME

6       LWP::ConsoleLogger - LWP tracing and debugging
7

VERSION

9       version 0.000042
10

SYNOPSIS

12       The simplest way to get started is by adding
13       LWP::ConsoleLogger::Everywhere to your code and then just watching your
14       output.
15
16           use LWP::ConsoleLogger::Everywhere ();
17
18       If you need more control, look at LWP::ConsoleLogger::Easy.
19
20           use LWP::ConsoleLogger::Easy qw( debug_ua );
21           use WWW::Mechanize;
22
23           my $mech           = WWW::Mechanize->new;   # or LWP::UserAgent->new() etc
24           my $console_logger = debug_ua( $mech );
25           $mech->get( 'https://metacpan.org' );
26
27           # now watch the console for debugging output
28           # turn off header dumps
29           $console_logger->dump_headers( 0 );
30
31           $mech->get( $some_other_url );
32
33       To get down to the lowest level, use LWP::ConsoleLogger directly.
34
35           my $ua = LWP::UserAgent->new( cookie_jar => {} );
36           my $console_logger = LWP::ConsoleLogger->new(
37               dump_content       => 1,
38               dump_text          => 1,
39               content_pre_filter => sub {
40                   my $content      = shift;
41                   my $content_type = shift;
42
43                   # mangle content here
44                   # ...
45
46                   return $content;
47               },
48           );
49
50           $ua->default_header(
51               'Accept-Encoding' => scalar HTTP::Message::decodable() );
52
53           $ua->add_handler( 'response_done',
54               sub { $console_logger->response_callback( @_ ) } );
55           $ua->add_handler( 'request_send',
56               sub { $console_logger->request_callback( @_ ) } );
57
58           # now watch debugging output to your screen
59           $ua->get( 'http://nytimes.com/' );
60
61       Sample output might look like this.
62
63           GET http://www.nytimes.com/2014/04/24/technology/fcc-new-net-neutrality-rules.html
64
65           GET params:
66           .-----+-------.
67           | Key | Value |
68           +-----+-------+
69           | _r  | 1     |
70           | hp  |       |
71           '-----+-------'
72
73           .-----------------+--------------------------------.
74           | Request Header  | Value                          |
75           +-----------------+--------------------------------+
76           | Accept-Encoding | gzip                           |
77           | Cookie2         | $Version="1"                   |
78           | Referer         | http://www.nytimes.com?foo=bar |
79           | User-Agent      | WWW-Mechanize/1.73             |
80           '-----------------+--------------------------------'
81
82           ==> 200 OK
83
84           Title: The New York Times - Breaking News, World News & Multimedia
85
86           .--------------------------+-------------------------------.
87           | Response Header          | Value                         |
88           +--------------------------+-------------------------------+
89           | Accept-Ranges            | bytes                         |
90           | Age                      | 176                           |
91           | Cache-Control            | no-cache                      |
92           | Channels                 | NytNow                        |
93           | Client-Date              | Fri, 30 May 2014 22:37:42 GMT |
94           | Client-Peer              | 170.149.172.130:80            |
95           | Client-Response-Num      | 1                             |
96           | Client-Transfer-Encoding | chunked                       |
97           | Connection               | keep-alive                    |
98           | Content-Encoding         | gzip                          |
99           | Content-Type             | text/html; charset=utf-8      |
100           | Date                     | Fri, 30 May 2014 22:37:41 GMT |
101           | NtCoent-Length           | 65951                         |
102           | Server                   | Apache                        |
103           | Via                      | 1.1 varnish                   |
104           | X-Cache                  | HIT                           |
105           | X-Varnish                | 1142859770 1142854917         |
106           '--------------------------+-------------------------------'
107
108           .--------------------------+-------------------------------.
109           | Text                                                     |
110           +--------------------------+-------------------------------+
111           | F.C.C., in a Shift, Backs Fast Lanes for Web Traffic...  |
112           '--------------------------+-------------------------------'
113

DESCRIPTION

115       BETA BETA BETA.  This is currently an experiment.  Things could change.
116       Please adjust accordingly.
117
118       It can be hard (or at least tedious) to debug mechanize scripts.
119       LWP::Debug is deprecated.  It suggests you write your own debugging
120       handlers, set up a proxy or install Wireshark.  Those are all workable
121       solutions, but this module exists to save you some of that work.  The
122       guts of this module are stolen from Plack::Middleware::DebugLogging,
123       which in turn stole most of its internals from Catalyst.  If you're new
124       to LWP::ConsoleLogger, I suggest getting started with the
125       LWP::ConsoleLogger::Easy wrapper.  This will get you up and running in
126       minutes.  If you need to tweak the settings that
127       LWP::ConsoleLogger::Easy chooses for you (or if you just want to be
128       fancy), please read on.
129
130       Since this is a debugging library, I've left as much mutable state as
131       possible, so that you can easily toggle output on and off and otherwise
132       adjust how you deal with the output.
133

CONSTRUCTOR

135   new()
136       The following arguments can be passed to new(), although none are
137       required.  They can also be called as methods on an instantiated
138       object.  I'll list them here and discuss them in detail below.
139
140       ·   "dump_content => 0|1"
141
142       ·   "dump_cookies => 0|1"
143
144       ·   "dump_headers => 0|1"
145
146       ·   "dump_params => 0|1"
147
148       ·   "dump_status => 0|1"
149
150       ·   "dump_text => 0|1"
151
152       ·   "dump_title => 0|1"
153
154       ·   "dump_text => 0|1"
155
156       ·   "dump_uri => 0|1"
157
158       ·   "content_pre_filter => sub { ... }"
159
160       ·   "headers_to_redact => ['Authentication', 'Foo']"
161
162       ·   "params_to_redact => ['token', 'password']"
163
164       ·   "text_pre_filter => sub { ... }"
165
166       ·   "html_restrict => HTML::Restrict->new( ... )"
167
168       ·   "logger => Log::Dispatch->new( ... )"
169
170       ·   "pretty => 0|1"
171
172       ·   "term_width => $integer"
173

SUBROUTINES/METHODS

175   dump_content( 0|1 )
176       Boolean value. If true, the actual content of your response (HTML,
177       JSON, etc) will be dumped to your screen.  Defaults to false.
178
179   dump_cookies( 0|1 )
180       Boolean value. If true, the content of your cookies will be dumped to
181       your screen.  Defaults to false.
182
183   dump_headers( 0|1 )
184       Boolean value. If true, both request and response headers will be
185       dumped to your screen.  Defaults to true.
186
187       Headers are dumped in alphabetical order.
188
189   dump_params( 0|1 )
190       Boolean value. If true, both GET and POST params will be dumped to your
191       screen.  Defaults to true.
192
193       Params are dumped in alphabetical order.
194
195   dump_status( 0|1 )
196       Boolean value. If true, dumps the HTTP response code for each page
197       being visited.  Defaults to true.
198
199   dump_text( 0|1 )
200       Boolean value. If true, dumps the text of your page after both the
201       content_pre_filter and text_pre_filters have been applied.  Defaults to
202       true.
203
204   dump_title( 0|1 )
205       Boolean value. If true, dumps the titles of HTML pages if your
206       UserAgent has a "title" method and if it returns something useful.
207       Defaults to true.
208
209   dump_uri( 0|1 )
210       Boolean value. If true, dumps the URI of each page being visited.
211       Defaults to true.
212
213   pretty ( 0|1 )
214       Boolean value. If disabled, request headers, response headers, content
215       and text sections will be dumped without using tables. Handy for
216       copy/pasting JSON etc for faking responses later. Defaults to true.
217
218   content_pre_filter( sub { ... } )
219       Subroutine reference.  This allows you to manipulate content before it
220       is dumped.  A common use case might be stripping headers and footers
221       away from HTML content to make it easier to detect changes in the body
222       of the page.
223
224           $easy_logger->content_pre_filter(
225           sub {
226               my $content      = shift;
227               my $content_type = shift; # the value of the Content-Type header
228               if (   $content_type =~ m{html}i
229                   && $content =~ m{<!--\scontent\s-->(.*)<!--\sfooter}msx ) {
230                   return $1;
231               }
232               return $content;
233           }
234           );
235
236       Try to make sure that your content mangling doesn't return broken HTML
237       as that may not play well with HTML::Restrict.
238
239   request_callback
240       Use this handler to set up console logging on your requests.
241
242           my $ua = LWP::UserAgent->new;
243           $ua->add_handler(
244               'request_send',
245               sub { $console_logger->request_callback(@_) }
246           );
247
248       This is done for you by default if you set up your logging via
249       LWP::ConsoleLogger::Easy.
250
251   response_callback
252       Use this handler to set up console logging on your responses.
253
254           my $ua = LWP::UserAgent->new;
255           $ua->add_handler(
256               'response_done',
257               sub { $console_logger->response_callback(@_) }
258           );
259
260       This is done for you by default if you set up your logging via
261       LWP::ConsoleLogger::Easy.
262
263   text_pre_filter( sub { ... } )
264       Subroutine reference.  This allows you to manipulate text before it is
265       dumped.  A common use case might be stripping away duplicate whitespace
266       and/or newlines in order to improve formatting.  Keep in mind that the
267       "content_pre_filter" will have been applied to the content which is
268       passed to the text_pre_filter.  The idea is that you can strip away an
269       HTML you don't care about in the content_pre_filter phase and then
270       process the remainder of the content in the text_pre_filter.
271
272           $easy_logger->text_pre_filter(
273           sub {
274               my $content      = shift;
275               my $content_type = shift; # the value of the Content-Type header
276               my $base_url     = shift;
277
278               # do something with the content
279               # ...
280
281               return ( $content, $new_content_type );
282           }
283           );
284
285       If your "text_pre_filter()" converts from HTML to plain text, be sure
286       to return the new content type (text/plain) when you exit the sub.  If
287       you do not do this, HTML formatting will then be applied to your plain
288       text as is explained below.
289
290       If this is HTML content, HTML::Restrict will be applied after the
291       text_pre_filter has been run.  LWP::ConsoleLogger will then strip away
292       some whitespace and newlines from processed HTML in its own opinionated
293       way, in order to present you with more readable text.
294
295   html_restrict( HTML::Restrict->new( ... ) )
296       If the content_type indicates HTML then HTML::Restrict will be used to
297       strip tags from your content in the text rendering process.  You may
298       pass your own HTML::Restrict object, if you like.  This would be
299       helpful in situations where you still do want to have some tags in your
300       text.
301
302   logger( Log::Dispatch->new( ... ) )
303       By default all data will be dumped to your console (as the name of this
304       module implies) using Log::Dispatch.  However, you may use your own
305       Log::Dispatch module in order to facilitate logging to files or any
306       other output which Log::Dispatch supports.
307
308   term_width( $integer )
309       By default this module will try to find the maximum width of your
310       terminal and use all available space when displaying tabular data.  You
311       may use this parameter to constrain the tables to an arbitrary width.
312

CAVEATS

314       Aside from the BETA warnings, I should say that I've written this to
315       suit my needs and there are a lot of things I haven't considered.  For
316       example, I'm mostly assuming that the content will be text, HTML, JSON
317       or XML.
318
319       The test suite is not very robust either.  If you'd like to contribute
320       to this module and you can't find an appropriate test, do add something
321       to the example folder (either a new script or alter an existing one),
322       so that I can see what your patch does.
323

AUTHOR

325       Olaf Alders <olaf@wundercounter.com>
326
328       This software is Copyright (c) 2014-2019 by MaxMind, Inc.
329
330       This is free software, licensed under:
331
332         The Artistic License 2.0 (GPL Compatible)
333
334
335
336perl v5.30.1                      2020-01-30             LWP::ConsoleLogger(3)
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