So there’s two ways you can go about displaying blocks on your site.

  • You can use the excellent contexts module which will allow you to create smart contexts within your site and basically do what I’m going to explain below with no PHP code.
  • You write php code in your block display textarea to get what you want to show up. You might do this if you’re doing something simple or you don’t want the added complexity of installing context.

So if you’re writing php code it’s a pain to get all the different conditions right so I’m going to outline most of the major things you would want to do. First off you’re going to want to set up the condition, depending on if you want the block to display by default and have a condition that prevents it from displaying or if you want the block hidden by default and displayed if a condition is met.
//set default no or yes
$match = FALSE;
//condition goes here
return $match;

Next you’re going to want to add some conditions where I indicated above. Here’s how to display a block based on content type:
//match article type
$types = array('content_type' => 1);
if (arg(0) == 'node' && is_numeric(arg(1))) {
$nid = arg(1);
$node = node_load(array('nid' => $nid));
$type = $node->type;
if (isset($types[$type])) {
$match = TRUE;
}
}

Here’s how to display a block based on vocabulary ID on a term page:
//check for a vid
if ( ((arg(0) == 'taxonomy')
&& (arg(1) == 'term')
&& is_numeric(arg(2))
&& ($term = taxonomy_get_term(arg(2)))
&& ($term->vid == 7 )) ) {
$match = TRUE;
}

Here’s how to display a block based on a URL:
//videos page check
if(arg(0) == 'videos'){return false;}

Here’s how to display a block based on the taxonomy term hierarchical level on a term page:
//is this is a taxonomy page
if (arg(0) == 'taxonomy')
{ $match = TRUE;}

//taxonomy level
if (arg(0) == 'taxonomy'){
$term_parents = taxonomy_get_parents_all(arg(2));

//highest level
if(count($term_parents) == 1){
$match = TRUE;
}
//second level
if(count($term_parents) == 2){
$match = TRUE;
}
//third level
if(count($term_parents) == 3){
$match = TRUE;
}
}

I’ll be posting some more block display rules in the near future.