Re: wml::des::navbar: automatically selecting the right button

[nospam@thanx (Ralf S. Engelschall)]

Hello Oliver Hensel, in a previous mail you wrote:

> I currently have some question.
> I am using the great wml::des::navbar feature.
> I want to use a template, which automatically renders the navbar.
> That actually works, but I want to have the right button automatically selected
> by filename. 
> I have no clue how to do that, does anyone of you??

Which button is rendered "selected" is set via the "select=ID" attribute of
<navrender>. Ok, here you have to choices:

1. You do it manually like me via a #use attribute.
   My WML pages just do

   | #use wml::tmpl:swpage area=XXX

   and the tmpl/swpage.wml file contains

   | <navbar select=$(area) [...]>

   I personally have no problem with this.

2. You can do it automatically what you want, based
   on the filesystem structure. Here the keys are the two variables
   WML_SRC_DIRNAME and WML_SRC_FILENAME. The last one usually holds something
   like "index.wml".  What you now have to do is the following: Use these
   filenames as the button id (<nb_button name=ID>!) and render your navbar
   via
      <navrender select=<get-var WML_SRC_FILENAME> [...]>
   When you cannot do it such simple, i.e. need more difficult mapping between
   WML_SRC_DIRNAME/WML_SRC_FILENAME to the ID, you have to use a trick:

   | <:{
   |     my $dir  = '<get-var WML_SRC_DIRNAME>';
   |     my $file = '<get-var WML_SRC_FILENAME>';
   |     ...do some calculations here in Perl and 
   |        store result into global Perl variabe $id...
   | }:>
   | <navrender select="$id" [...]>

   This approach can solve any problem of automatic selection because now you
   have the complete power of Perl to do the calculation of the button to be
   selected. When you are crazy you can even use Perl's DBI interface here to
   resolve the button id from a database ;_)

Greetings,
                                       Ralf S. Engelschall
                                       rse@engelschall.com
                                       www.engelschall.com
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