How to show a block only on the nodes which the user created

Question

I have a block that I only want to display in nodes that the current user created. What's the best way of going about this?

Thoughts so far

I can access $user (and therefore the UID) anywhere, so I need to compare this to the node author UID. The only problem is finding a place where I can also pull in the current node information to find out it's author.

I really don't want to put php in a block (bad practice and all) and I couldn't see where I'd do this in context.

If I can't find a better way then the backup plan is to create an automatic field on node creation which contains the authors UID, then use this in page.tpl.php to set a class which will apply display:node to the block whenever the author UID =! user UID.

EDIT: Solution

The block I was trying to effect was in a custom module, so I took Yuriy's code and put into the modules hook_block_view. The result was this:

function mymodulename_block_view($delta = '') {
  $block = array();
  switch($delta) {
    case 'mymodulename_form':
            if (preg_match('#node/([0-9]+)#', $_GET['q'], $matches)) {
              if ($node = node_load($matches[1])) {
                global $user;
                if ($user->uid !== $node->uid) {
                  $block['content'] = array();
                } else {
                  $block['content'] = drupal_get_form('mymodulename_form');
                }
              }
            }
    break;
  }
  return $block;
}

I think this is what's going on:

preg_match and $_GET are used to take the node path from the current page. This returns: "node/xx". This is then used to load the correct node which is then matched against the global UID. An if function then either empties the block content or fills it.

Answer 1

I would implement hook_block_view_alter() and remove the block's content (resulting in hiding the block). Something like this (untested):

function hook_block_view_alter(&$data, $block) {
  if ($block->module == 'somemMdule' && $block->delta == 'someDelta' && preg_match('#node/([0-9]+)#', $_GET['q'], $matches)) {
    if ($node = node_load($matches[1])) {
      global $user;
      if ($user->uid !== $node->uid) {
        $data['content'] = array();
      }
    }
  }
}

Answer 2

I don't understand your reluctance to use php in a block, particularly in the block visibility settings.

If you set the block to display only on the pages where the following php code returns true, then the following, or something similar, should do the job for you.

<?php
global $user;
$node = menu_get_object();
return ( $user->uid == $node->uid );
?>