How do I use and debug WWW::Mechanize?

Question

Hi guys,

I am very new to Perl and i am learning on the fly while i try to automate some projects for work. So far its has been a lot of fun.

I am working on generating a report for a customer. I can get this report from a web page i can access. First i will need to fill a form with my user name, password and choose a server from a drop down list, and log in. Second i need to click a link for the report section. Third a need to fill a form to create the report.

Here is what i wrote so far:

my $mech = WWW::Mechanize->new();
my $url = 'http://X.X.X.X/Console/login/login.aspx';

$mech->get( $url );

$mech->submit_form(
     form_number => 1,
     fields      =>{
        'ctl00$ctl00$cphVeriCentre$cphLogin$txtUser'  => 'someone',
        'ctl00$ctl00$cphVeriCentre$cphLogin$txtPW'    => '12345',
        'ctl00$ctl00$cphVeriCentre$cphLogin$ddlServers'  => 'Live',
     button => 'Sign-In'
   },   
);
die unless ($mech->success);

$mech->dump_forms();

I dont understand why, but, after this i look at the what dump outputs and i see the code for the first login page, while i belive i should have reached the next page after my successful login.

Could there be something with a cookie that can effect me and the login attempt?

Anythings else i am doing wrong?

Appreciate you help, Yaniv

Answer 1

You can only mechanize stuff that you know. Before you write any more code, I suggest you use a tool like Firebug and inspect what is happening in your browser when you do this manually.

Of course there might be cookies that are used. Or maybe your forgot a hidden form parameter? Only you can tell.

EDIT:

• WWW::Mechanize should take care of cookies without any further intervention.
• You should always check whether the methods you called were successful. Does the first get() work?
• It might be useful to take a look at the server logs to see what is actually requested and what HTTP status code is sent as a response.

Answer 2

Are those field names really the field names used in the form? With the dollar signs? If you're trying to use variables there you shouldn't be using single quotes.

Answer 3

This is several months after the fact, but I resolved the same issue based on a similar questions I asked. See http://stackoverflow.com/questions/1018241/is-it-possible-to-automate-postback-from-the-client-side for more info.

I used Python's Mechanize instead or Perl, but the same principle applies.

Summarizing my earlier response:

ASP.NET pages need a hidden parameter called __EVENTTARGET in the form, which won't exist when you use mechanize normally.

When visited by a normal user, there is a __doPostBack('foo') function on these pages that gives the relevant value to __EVENTTARGET via a javascript onclick event on each of the links, but since mechanize doesn't use javascript you'll need to set these values yourself.

The python solution is below, but it shouldn't be too tough to adapt it to perl.

def add_event_target(form, target):
    #Creates a new __EVENTTARGET control and adds the value specified
    #.NET doesn't generate this in mechanize for some reason -- suspect maybe is 
    #normally generated by javascript or some useragent thing?
    form.new_control('hidden','__EVENTTARGET',attrs = dict(name='__EVENTTARGET'))
    form.set_all_readonly(False)
    form["__EVENTTARGET"] = target