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| | Dreamwidth is currently in the process of moving away from [[BML]] and towards a system of routing that employs [http://template-toolkit.org/ Template Toolkit] for templates. | | Dreamwidth is currently in the process of moving away from [[BML]] and towards a system of routing that employs [http://template-toolkit.org/ Template Toolkit] for templates. |
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| − | == The Basics ==
| + | More information on how to use this system can be found in: |
| | | | |
| − | Making a page with the routing and Template Toolkit system requires a few things:
| + | * [[Routing and Template Cookbook]] |
| | | | |
| − | # Define a URL string or pattern
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| − | # Create a handler function, attached to the URL string or pattern
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| − | # Make any needed templates
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| − |
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| − | === Defining a URL ===
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| − |
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| − | Here are some examples of registering a URL. There are two main functions to do this with, <tt>register_string</tt> and <tt>register_regex</tt>.
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| − |
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| − | <source lang="perl">
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| − | # This registers a static string, which is an application page.
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| − | DW::Routing::Apache2->register_string( '/misc/whereami', \&whereami_handler,
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| − | app => 1 );
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| − |
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| − | # This registers a regular expression. Later, we can get the
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| − | # contents inside the parentheticals. This lets us make "clean" urls
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| − | # like /nav/read and /nav/create that are equivalent to
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| − | # /nav?cat=create
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| − | DW::Routing::Apache2->register_regex( qr!^/nav(?:/([a-z]*))?$!, \&nav_handler,
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| − | app => 1 );
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| − |
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| − | # This registers a user page, so, for example, it would be accessed at
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| − | # username.dreamwidth.org/data/edges
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| − | # This also explicitly sets our default output format to be JSON.
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| − | DW::Routing::Apache2->register_string( "/data/edges", \&edges_handler,
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| − | user => 1, format => 'json' );</source>
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| − |
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| − | === Creating a handler function ===
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| − |
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| − | I'm going to use the Nav controller as an example. You can see the entire page at [http://hg.dwscoalition.org/dw-free/file/tip/cgi-bin/DW/Controller/Nav.pm DW::Controller::Nav.pm].
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| − |
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| − | We define our URL in the same file we place the handler function, so we'll start there:
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| − |
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| − | <source lang="perl">package DW::Controller::Nav;
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| − |
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| − | use strict;
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| − | use warnings;
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| − | use DW::Controller;
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| − | use DW::Routing::Apache2;
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| − | use DW::Template::Apache2;
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| − | use DW::Logic::MenuNav;
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| − | use JSON;
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| − |
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| − | # Defines the URL for routing. I could use register_string( '/nav' ... ) if I didn't want to capture arguments
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| − | # This is an application page, not a user styled page, and the default format is HTML (ie, /nav gives /nav.html)
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| − | DW::Routing::Apache2->register_regex( qr!^/nav(?:/([a-z]*))?$!, \&nav_handler, app => 1 );</source>
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| − |
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| − | First, I want to get the options and request:
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| − |
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| − | <source lang="perl"># handles menu nav pages
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| − | sub nav_handler {
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| − | my $opts = shift;
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| − | my $r = DW::Request->get;</source>
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| − |
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| − | Remember that subpattern I made in my URL regex? I'll figure out if I'm using it or an argument here.
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| − |
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| − | <source lang="perl">
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| − | # Check for a category like nav/read, then for a ?cat=read argument, else no category
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| − | my $cat = $opts->subpatterns->[0] || $r->get_args->{cat} || '';</source>
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| − |
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| − | Here, I'm doing error checking. If I don't get back the array of menu hashe, I'm going to serve an error page that contains a translated error message. Notice how I have to define the whole path to the error message, and can't just use ".error.invalidcat".
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| − |
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| − | <source lang="perl"> # this function returns an array reference of menu hashes
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| − | my $menu_nav = DW::Logic::MenuNav->get_menu_display( $cat )
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| − | or return error_ml( '/nav.tt.error.invalidcat' );</source>
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| − |
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| − | I'm getting some cruft that is needed by the real menu that I don't want to display on this page, so I'll go through all the menus and strip out HTML from the titles. Ideally there would be a Template Toolkit filter that could do this, but I have not found one yet; we may have to make one.
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| − |
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| − | <source lang="perl"> # this data doesn't need HTML in the titles, like in the real menu
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| − | for my $menu ( @$menu_nav ) {
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| − | for my $item ( @{ $menu->{items} } ) {
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| − | $item->{text} = LJ::strip_html( $item->{text} );
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| − | }
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| − | }</source>
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| − |
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| − | This is a nifty part. I can display the contents of this page either as HTML or as JSON (which is made for machine parsing), with very very little additional code.
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| − |
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| − | The first one is how to return something as JSON. I just print out the object conversion to the request and return OK.
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| − |
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| − | <source lang="perl"> # display according to the format
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| − | my $format = $opts->format;
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| − | if ( $format eq 'json' ) {
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| − | # this prints out the menu navigation as JSON and returns
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| − | $r->print( JSON::objToJson( $menu_nav ) );
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| − | return $r->OK;</source>
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| − |
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| − | The HTML format takes a bit more work. We want to pass in more variables to the template and return the rendered template.
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| − |
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| − | Here we go preparing the variables:
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| − |
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| − | <source lang="perl"> } elsif ( $format eq 'html' ) {
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| − | # these variables will get passed to the template
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| − | my $vars = {
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| − | menu_nav => $menu_nav,
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| − | cat => $cat,
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| − | };
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| − |
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| − | $vars->{cat_title} = $menu_nav->[0]->{title} if $cat;</source>
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| − |
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| − | And this is the call to render our template (more on making that next):
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| − |
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| − | <source lang="perl"> # Now we tell it what template to render and pass in our variables
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| − | return DW::Template::Apache2->render_template( 'nav.tt', $vars );</source>
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| − |
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| − | If my format isn't HTML or JSON, we throw a 404.
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| − |
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| − | <source lang="perl"> } else {
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| − | # return 404 for an unknown format
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| − | return $r->NOT_FOUND;
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| − | }
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| − | }
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| − |
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| − | 1;</source>
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| − |
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| − | And that's the handler!
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| − |
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| − | === Creating a template ===
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| − |
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| − | The template will be placed somewhere logical in <tt>$LJHOME/views</tt>. This one will be <tt>[http://hg.dwscoalition.org/dw-free/file/tip/views/nav.tt nav.tt]</tt>. Currently, translation strings will go in <tt>nav.tt.text</tt>.
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| − |
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| − | This section is a comment:
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| − |
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| − | <source lang="html4strict">
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| − | [%# nav.tt
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| − |
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| − | Page that shows the sub-level navigation links given the top-level navigation header
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| − |
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| − | %]</source>
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| − |
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| − | This section sets the title of the page. If we have a category, it will be the category title. Otherwise, it will use the ML translation of the title for the page.
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| − |
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| − | <source lang="html4strict">[%- IF cat; sections.title = cat_title; ELSE; sections.title = '.title' | ml; END -%]</source>
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| − |
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| − | This section creates the menu sections, applying code for each menu and each item in each menu. If this isn't only displaying a category, it makes the title. You can see the [http://template-toolkit.org/docs/manual/Filters.html#section_html html filter] being used in places like <tt>[% menu.title | html %]</tt> to ensure that all HTML is safe, and the [http://template-toolkit.org/docs/manual/Filters.html#section_url url filter] being used in <tt>[% menu_item.url | url %]</tt> to make sure that URL will be validly encoded.
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| − |
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| − | <source lang="html4strict">[% FOREACH menu = menu_nav %]
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| − | [% IF NOT cat %]<h2 class="[% menu.name %]">[% menu.title | html %]</h2>[% END %]
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| − | <ul>
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| − | [% FOREACH menu_item = menu.items %]
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| − | <li><a href="[% menu_item.url | url %]">[% menu_item.text | html %]</a></li>
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| − | [% END %]
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| − | </ul>
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| − | [% END %]
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| − | </source>
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| − |
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| − | That template is all that's required to render the HTML for the nav page! You can see it [http://www.dreamwidth.org/nav live on Dreamwidth].
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| − |
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| − | == References ==
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| − |
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| − | * [http://template-toolkit.org/docs/index.html Template Toolkit Documentation]
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| − |
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| − | === Code Modules ===
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| − |
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| − | * [http://hg.dwscoalition.org/dw-free/file/tip/cgi-bin/DW/Controller.pm DW::Controller]
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| − | * [http://hg.dwscoalition.org/dw-free/file/tip/cgi-bin/DW/Request.pm DW::Request]
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| − | * [http://hg.dwscoalition.org/dw-free/file/tip/cgi-bin/DW/Routing/Apache2.pm DW::Routing::Apache2]
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| | [[Category: Development]] | | [[Category: Development]] |
