Hi Andy,
Some time a ago, I sent you the text for the FAQ on Java script. There
is a section "So what do I do". I would like to suggest that you update
the text:
Original text:
So what can I do?
Since Javascript is completely visible to the client, it cannot be
used to prevent a scraper from following links. But it can make life
difficult, and until someone writes a Javascript interpreter for
Perl or a Mechanize clone to control Firefox, there will be no
general solution. But if you want to scrape specific pages, then a
solution is always possible.
One typical use of Javascript is to perform argument checking before
posting to the server. The URL you want is probably just buried in
the Javascript function. Do a regular expression match on
|$mech->content()| to find the link that you want and |$mech->get|
it directly (this assumes that you know what your are looking for in
advance).
In more difficult cases, the Javascript is used for URL mangling to
satisfy the needs of some middleware. In this case you need to
figure out what the Javascript is doing (why are these URLs always
really long?). There is probably some function with one or more
arguments which calculates the new URL. Step one: using your
favorite browser, get the before and after URLs and save them to
files. Edit each file, converting the the argument separators ('?',
'&' or ';') into newlines. Now it is easy to use diff or comm to
find out what Javascript did to the URL. Step 2 - find the function
call which created the URL - you will need to parse and interpret
its argument list. Using the Javascript Debugger Extension for
Firefox may help with the analysis. At this point, it is fairly
trivial to write your own function which emulates the Javascript for
the pages you want to process.
Please append to it:
An Alternative Approach (this is also an answer to the question, "It
works in Firefox, why not in $mech?" )
Everything the web server knows about the client is present in the
HTTP request. If two requests are identical, the results should be
identical. So the real question is "What is different between the
mech request and the Firefox request?"
I would suggest using the Firefox extension "Tamper Data" to look at
the headers of the requests you send to the server. Compare that
with what LWP is sending. Once the two are identical, the action of
the server should be the same as well.
I say "should", because this is an oversimplification - some values
are naturally unique, e.g. a SessionID, but if a SessionID is
present, that is probably sufficient, even though the value will be
different between the LWP request and the Firefox request. The
server could use the session to store information which is
troublesome, but that's not the first place to look (and highly
unlike to be relevant when you are requesting the login page of your
site).
Generally the problem is to be found in missing or incorrect
POSTDATA arguments, Cookies, User-Agents, Accepts, etc. If you are
using mech, then redirects and cookies should not be a problem, but
are listed here for completeness. If you are missing headers,
$mech->add_header can be used to add the headers that you need.
Is there a preferred way to get the request which mech is going to send?
I was able to get it by following the code into the innards of
HTTP::Request, but that seems like the kind of stuff a $mechanize user
won't want to do.
Cheers,
Peter
Cahoon, Forrest wrote:
If you're specifically looking at Yahoo! Mail, there's at least one CPAN module
for that:
http://search.cpan.org/~johnsca/MailClientYahoo-1.0/lib/Mail/Client/Yahoo.pm
If it's just something similar to Yahoo!, perhaps that code will give you some
clues.
(I haven't used that module myself, just happened to notice it's existence.)
Forrest
not speaking for merrill corporation
-----Original Message-----
From: Roy Lor [mailto:[EMAIL PROTECTED]
Sent: Tuesday, April 04, 2006 8:21 AM
To: libwww@perl.org
Subject: WWW::Mechanize
can u give me a code/script that records the information in a
log-in form with javascript..like that of mail.yahoo.com? i
badly need this..thanks
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