setting the url to a function in a custom module

Question

I am trying to make a link in a view which, when clicked on, will call a function in a custom module to make a database call. I have made a link by making a Global:custom text field (because thats the way it seemed I had to do it from some posts online), set it to a path accompanied with some arguments. I made a custom module used the hook_menu:

function example_menu() {
$items = array();
$items['path_name'] = array(
'title' => t('Example'),
'page callback' => 'my_callback',
'access arguments' => array('access content'),  
'type' => MENU_CALLBACK,
);
return $items;
}

where function my_callback does a database call.

When I click on the link I just get a blank page with nothing on it. Which pieces am I missing here? The first thing I thought was that I needed to route the link to a page (hence the name 'page_callback') but how would I do this? All I really want done is a database call, I don't mind if you stay on the same page.

EDIT: Additionally, what I have found is that on the content management page there ares some errors on top which tell me that I'm missing arguments 1 through 4 (there were four arguments), which definitly can be part of the problem. The function starts off:

function example_my_callback($staff_action, $first_name, $last_name, $email)

and the url for the link was path_name?staff_action=[varible name found in views]...etc Is there any issue here?

Answer 1

The page callback function generates the html that is shown on the page when you surf over to it, so, you would do something like this in it:

function my_callback() {

  // do your db stuff

  if ( // success ) {
    return '<div>Success</div>';
  else {
    return '<div>Failure</div>';
  }

}

And a link to it is just like any other html link, it goes to a page. If you want to stay on the current page, you will need to do it via ajax/ahah or something similarly fun with javascript/jquery etc.

Answer 2

The page callback must be the name of the function that will return the data from database

You must create a function like this :

function my_callback(){
// here you will connect and pull up data from the database
return $your_data;
}

Also don't forget to clear the cache and read about the database API here