Blocks are a great way to code a little application for indexU without having to get swamped in code from other core files. In this block tutorial i will show you how to write a block for the detail page. This block will flow as follows :

1) Block is called from the detail_link.html file
2) The Block passes the variable "link_id" to the php file, this allows us to know which link we are dealing with
3) The php file collects the Link_id as a "parameter" does a query to the database using it.
4) We assign the result to a template and display it.

The block is going to be called "hit counter", so lets start with the easy bit and place the following code in detail_link.html

<%block_hitcounter%>

This will now cause an error, we have 2 problems with the above. Firstly it does not pass the link_id, the second problem is that its going to look for a file called "hitcounter.php" which currently does not exist. Lets fix these problems. Firstly lets pass the link Id to it .

<%block_hitcounter id="$link_id"%>

my changes, in Kosmos theme, now looks like this :

 <tr class="tbl_normal">
    <td>Url</td>
    <td><a href="<%$url%>" name="link_<%$link_id%>"><%$url%></a> ( hits : <%block_hitcounter id="$link_id"%> )</td>
  </tr>

Now to create the block, paste the following  into a new document and save it down to blocks/block.hitcounter.php 

<?php
function block_hitcounter($params) {
  global $dbConn, $id;
 
 
   if (!$params['template']) {
    $params['template'] = 'block.hitcounter.html';
  }

//here i assign the parameter passed to the php file to a variable called "id"
 $id= $params['id'];

  $tpl = new Template;

// here i do a query ont he database
  $query = "select hits as h from idx_link where link_id=$id";
  $result = $dbConn->Execute($query);
// assign the resultign field to a variable called hits
  $hits = $result->Fields("h");

// assign the variable to the template.
  $tpl->assign("hits", $hits);
  $tpl->display("blocks/" . $params['template']);
}

?>

read the comments to figure out what is happening in the file, if your creating your own block then you can use the above example as a basis. It demonstrates how you pass a value to the php file, execute some code, the put the result back to a template. 

 Now all we need to do is create the html file, we dont need any layout on the template file so create a new document, save it as themes/blocks/block.hitcounter.html 

 All you need in this file is : <%$hits%> Now upload everything and try it out!

 This is a very basic example, I will cover how to work with loops in a subsequent article. 

Things to watch out for
The function name at the top (function block_hitcounter($params) { ) must start with block_ and then be the exact filename otherwise it will not execute. The code used to callt he block must always be <%block_hitcounter%> (note you dont use the "$" like you would with a custom field as this is not a variable. Lastly, make sure that any variables you pass to the php file are enclosed in quotes "like this"