wordpress plugin: query post-ID in plugin?

Question

hey guys, maybe some of you have experience with programming wordpress plugins. I have a probably rather simpel question, but i couldn\'t find anything on the web.

Answer 1

Filters should return, not echo.

function test($content) {
    global $post;
    return 'id: ' . $post->ID . '<br />' . $content;
}

In order to look at the post object properties you must bring $post into the scope of the function, that's what this line does..

global $post;

Which then allows the reference to the object's ID, eg.

$post->ID;

See here for help understanding actions and filters.
http://codex.wordpress.org/Plugin_API

Example filter.
http://codex.wordpress.org/Plugin_API#Example

Answer 2

You're mixing echo and return - that doesnt work. However, try:

function test($content) 
{
    return "id: ".$post_id."<br/>".$content;
}

also, make sure to use lowercase id, as it is case-sensitive

http://codex.wordpress.org/Function_Reference/get_the_ID might be usefull aswell

Answer 3

My guess is Use global keyword to access post id in function

And also my guess is return and echo both would not work together in function

function test($content) {
        global $post;
        return $post->ID.'<br>'.$content;
    }