Override taxonomy term view behavior

I'm afraid I don't understand what you mean, Nevets, and I don't want to rely on views at this time.

I am at the point where I can create and maintain a menu that is based on a taxonomy (like the taxonomy_menu module) and now I want to allow the user to configure the number of sublevels to show on a taxonomy term page (taxonomy/term/$term_id).

I was expecting that hook_taxonomy_term_view_alter(&$build) would enable me to hook into the proces that creates the array of nodes that are displayed on a term page, but it doesn't fire when I'm on a term page.

Is there any way to hook into the process that generates the node list for a term page?

I don't know when hook_taxonomy_term_view_alter runs, so I've abandoned that..

Right now I am using hook_page_alter to get the extra nodes I need on the taxonomy term page. Here's the code.

function mymodule_page_alter(&$page){
    $pathParts = explode("/", current_path());
    // If we're on a term page...
    if(count($pathParts) == 3 && $pathParts[0] == "taxonomy" && $pathParts[1] = "term" && 
        is_numeric($pathParts[2])){
         
        // Load the current term   
        $termId = $pathParts[2];
        $term = taxonomy_term_load($termId);
        // Get its children
        $children = taxonomy_get_children($term->tid, $term->vid);
        $extraNodeIds = array(); 
        // For each child term get the associated node ids
        foreach($children as $childTerm){
            $extraNodeIds = array_merge($extraNodeIds, taxonomy_select_nodes($childTerm->tid));
        }  
        // Fetch extra nodes for display
        $nodes = node_load_multiple($extraNodeIds);
        
        // Yargh... how do I add the extra nodes to the $page?
    }
}

All I need now is to add the extra nodes I have in $nodes to the $page, but how? The $page array is structured in a way I didn't expect. The actual nodes are nested pretty deeply like this. The nodes in the $page array start at [n], for example [15], and the nodes I have in my $nodes array are objects that start at "[#object] => stdClass Object". How to bridge this gap? There must be a more elegant way to do this..

   [content] => Array
        (
            [system_main] => Array
                (
                    [nodes] => Array
                        (
                            [15] => Array
                                (
                                    [body] => Array
                                        (
                                            [#theme] => field
                                            [#weight] => 0
                                            [#title] => Body
                                            [#access] => 1
                                            [#label_display] => hidden
                                            [#view_mode] => teaser
                                            [#language] => und
                                            [#field_name] => body
                                            [#field_type] => text_with_summary
                                            [#field_translatable] => 1
                                            [#entity_type] => node
                                            [#bundle] => article
                                            [#object] => stdClass Object
                                                (
                                                    [vid] => 15
                                                    [uid] => 1
                                                    [title] => Programmeren 2 article
                                                    [log] => 

I solved this by using the hook_query_alter.

I am taking the number of sublevels I want to show nodes from from the config I built myself. Then, with that value I am overriding the query that is used by drupal to fetch nodes on a term page.

function mymodule_query_alter(QueryAlterableInterface $query){
    $pathParts = explode("/", current_path());
    // If we're on a term page and we're querying for nodes..
    if(count($pathParts) == 3 && 
        $pathParts[0] == "taxonomy" && 
        $pathParts[1] = "term" && 
        is_numeric($pathParts[2])){    
        
        // Get the tables from the query 
        $tables =& $query->getTables();
        
        // Isolate the node table
        if(isset($tables['base'])){
            if($tables['base']['table'] == 'node'){
                
                // Get the where clause
                $where =& $query->conditions();
                
                // Get the current term id
                $termId = $pathParts[2];
                
                // Create Dao
                $sectionDao = new SectionDao();  
                
                // Load the term association and the term itself. 
                // TODO: this could be done faster in one custom query...
                $association = $sectionDao->findTermLinkAssociationByTid($termId);
                $menuLink = menu_link_load($association['mlid']);
                
                // Determinte the min and max depth for child terms 
                $minDepth = 0;
                $maxDepth = 0;
                
                if($association['child_levels'] == 0){ 
                    // No further action is needed when no extra child levels are wanted: return
                    return;
                }else{   
                    // The minimal depth is the terms right under the current term               
                    $minDepth = $menuLink['depth'] + 1;
                    // The maximum depth is supplied by the user in the admin 
                    $maxDepth = $menuLink['depth'] + $association['child_levels'];
                }
                
                $childTermKeys = array();
                // Fetch the child terms under the current term/link, untill the max depth
                $extraMenuItems =
                    $sectionDao->findChildItems($association['mlid'], $minDepth, $maxDepth);

                $extraNodeIds = array(); 
                // Select the extra nodes
                // TODO:  This loop is a potential performance problem with large vocabs
                foreach($extraMenuItems as $extraMenuItem){
                    $extraNodeIds = array_merge($extraNodeIds, taxonomy_select_nodes($extraMenuItem->tid));    
                }

                // Add the extra node ids the where clause of the query
                $where[0]['value'] = array_merge($where[0]['value'], $extraNodeIds);
               
            }    
        }
    }     
}

Works like a charm. The user can select the number of sublevels he wants to display nodes from on a term page and the query is dynamically altered to include nodes from those sublevels.

Next step is to set conditional child levels like "when term page has less than 5 nodes, fetch 5 most recent nodes from subterm pages", etc.