Passing an argument to a node causes 404

Question

On my page I have a block that reads a variable in the URL. The page that it reads it on is a node. When I pass an argument through the URL to the node, it causes a 404 error. ex:

www.example.com/experience //This is the node, it works
www.example.com/experience/asia //Asia is the argument, I get 404

I've tried configuring the URL Alias to "experience/*", but this obviously didn't work and only accepts '*' as the argument. What do I need to configure to make this work?

I've heard of some modules that automatically add the aliases to the configuration table, but I would prefer a more straight-forward solution.

Answer 1

There are four points to consider:

• When you set a path alias, the asterisk is not used as wildcard character; this means that when you set experience/* as path alias, you are really saying to Drupal that http://example.com/experience/* is the path alias, not that http://example.com/experience/ followed by any string is the path alias.
• If http://example.com/experience is the path alias for http://example.com/node/4, http://example.com/experience/asia is not an alias for http://example.com/node/4/asia.
• Even if you would have set http://example.com/experience/asia as alias of http://example.com/node/4/asia, visiting http://example.com/experience/asia you would get a "page not found" error, as there are no modules that handles a path like http://example.com/node/4/asia
• Using the path in that way to pass arguments to a block shown in a node page is wrong, especially when the argument can be any string. What would happen if you access http://example.com/node/4/edit? Should "edit" be understood as part of the path, and Drupal should show the node edit form, or should be taken as argument to the block, and Drupal should simply show the node?

It is better if such parameter is passed as query string, for example in a URL like http://example.com/node/4?continent=asia. If you really like better to use a URL like http://example.com/experience/asia, then with Drupal 7 you can implement the following hooks.

function mymodule_url_outbound_alter(&$path, &$options, $original_path) {
  if ($path == 'node/4') {
    $path = 'experience';

    if (!empty($options['query']['continent'])) {
      $path .= "/{$options['query']['continent']}";
      unset($options['query']['continent']);
    }
  }
}

function mymodule_url_inbound_alter(&$path, $original_path, $path_language) {
  if (preg_match('|^experience(/(.*))?|', $path, $matches)) {
    $path = 'node/4';
    $_GET['continent'] = $matches[2];
  }
}

Answer 2

There are modules to accept subpath aliases.

If you're on Drupal 6 then look into the subpath_alias module.

Drupal 7 has subpathauto which does the same thing.

What they do is expand Drupal's path matching to work with subpaths, so no extra aliases are added. I've used it in the past when embedding views within nodes and it worked a treat.

So if you have node/4 aliased to path/test then it will recognise path/test/argument as node/4/argument

Answer 3

If you changed your url from

www.example.com/experience/asia

to

www.example.com/experience?type=asia

you should be able to access asia and any other "type" from your block like this:

$types = drupal_get_query_parameters();
foreach ($types as $key => $value){
  switch ($key) {
     case 'asia':
       // code for asia goes here...
       break;
     case 'europe':
       // code for europe goes here...
       break;
     // etc
  }
}

Otherwise, as the comments suggest, www.example.com/experience/whatever is going to fail because drupal hasn't declared a menu item for that path. However, variables can be passed in practically anywhere without drupal needing to know about them all as they don't change the base url.

If you still wanted the "cleaner" looking url, I suppose you could create a hook_menu() item like:

 $item['experience/%'] = array(
   'title' => 'Experience',
   'page callback' => 'experience_type',
   'access callback' => TRUE, 
   'type' => MENU_CALLBACK,
 );

and then function called experience_type that returned the contents of node/4 or whatever experience is aliased to. Then, in your block you could do something like:

switch (arg(1)) {
   case 'asia':
     // code for asia goes here...
     break;
   case 'europe':
     // code for europe goes here...
     break;
   // etc
}

and if all is good in the world, www.example.com/experience/asia would work.

Answer 4

It is better to implement hook_menu() and make a custom callback by placing a placeholder after your URL.