add content to bottom of single posts using functions.php

Not sure you can use add_action with the the_content? That is more for a filter where you are checking or amending the content.

What your code is doing is to replace the_content with the output from your function, you could try something like this (untested code!):

function tsi_source_link($content) {
 if ( is_single() ) {
   global $post;
   $source_link = get_post_meta ($post->ID, 'syndication_permalink', true);
   if ($source_link) {
   	$content .= '<div id="tsi-source-link" style="text-align:right;"><a href="' . $source_link . '" target="_blank">Read more ...</a></div>';
}
}
return $content;
}
add_action('the_content','tsi_source_link');

But perhaps better to add a wp_footer action then you can echo out your output as in your code above without making any amendments.

Hi Joe,

Yes, that sounds like a sensible approach, that is the wonderful thing about child themes, you can be much more adventurous in a safer environment.

The wp_footer action is triggered by a call to the wp_footer() function in the footer.php file of the theme (this is the case for Twenty Ten, may be modified in other themes). It does not do the echo for you, so you have to do this yourself in the function (as you did in your original code sample above). The code example for wp_footer in the Codex is:

<?php
add_action('wp_footer', 'your_function');

function your_function() {
  $content = '<p>This is inserted at the bottom</p>';
  echo $content;
}
?>

@madpress

what is your funcion code?

(if it is longer than 10 lines, please use the http://pastebin.com/ )

are you clear about when to use return and when to use echo ?

two small edits:

function madpress_test() {
		return "TEST"; }

and to show ‘test’ before the content:

$content = madpress_test() . $content;

Whoops, still a bit in the dark here. Is there a way to echo php stuff below the post content, along with the html? For example, the following displays the permalink above the post content, and the text “This is the” below the content.

function madpress_permalink() {
		echo the_permalink(); }
add_filter('the_content', 'add_test');
function add_test($content) {
	if (is_single()) {
		$content .= '<p>This is the ' . madpress_permalink() . '</p>';
	}
	return $content;
}

Excuse me, but I’m not seeing clear yet. Could you elaborate a little on what should be done to get the above working properly?

That’s right! One more question however: is it only possible then to return stuff which you can “get”? What if I would like to display today’s date for example?

<?php echo date('l jS F Y'); ?>

And on a general note: wouldn’t it be nice to have an action hook like loop_end for inserting stuff below the post content?