conditional image thumbnail on main blog page

Hi Jonny,

Replace your code with this one, it should work :

<?php
$image = get_post_meta($post->ID, 'thumbnail', true);
$link = get_permalink($post->ID);
if ($image == 0) {
echo '';
}
else {
echo  '<a href="'.$link.'" title="'.$post->post_title.'"><img src="'.$image.'" alt="" /></a>';
}
?>

This code looks if your $image variable is empty (if ($image == 0))

If so, it echoes nothing.

If there is something, it echoes the img tag enclosed in a link to the post.

I’m far than being a php guru, so maybe there is a more fancy way to write it, but as I said, it should work… ??

S.

By the way, I wrote a simple function to display the thumbnail of the first image attached to a post.

As I can see, you use the custom field to display your thumbnail. But you don’t need to do so. You can automatically display a thumbnail if you uploaded an image via the write post interface.

function the_post_thumbnail() {
global $wpdb;
global $post;
$thumb = $wpdb->get_var("SELECT ID FROM $wpdb->posts where post_parent= $post->ID and post_type = 'attachment'");
$thumbnail = wp_get_attachment_thumb_url($thumb);
if ($thumb == 0) {
echo '';
}
else {
echo '<img src="'.$thumbnail.'" alt="" />';
}
}

With this function in your functions.php (in your theme directory), you just have to use :

<?php the_post_thumbnail();?>

Anywhere in your loop to display the thumbnail… ??

S.

Thanks simon –

Unfortunately I tried putting your code into my functions.php and got this error whenever i tried to do anything else:

Warning: Cannot modify header information – headers already sent by (output started at /home/MY SITE NAME/wp-content/themes/geex3m/functions.php:433) in /home/MY SITE NAME/wp-admin/theme-editor.php on line 62

also the first code looks like it should work really well but doesn’t
Im sure it’s something im doing wrong… that warning message has got me worried though. I have now got rid of the code but it’s still doing it.

Hola Jonny

This error message means one thing : you likely have a space, a break line or a blank character in : functions.php at the line 433.

It’s a usual error read here.

https://codex.www.ads-software.com/Answers-Trouble_Shooting#Headers_already_sent

To avoid this kind of error, always edit your file with a good text editor, like notepad++

You can read the solutions in the codex page I linked above.

To repair it fast, just upload a fresh copy of functions.php from the original theme folder you downloaded.

—

For the first code I gave you, I didn’t test it with a custom field, I just putted your original line as the first varable. But I’m pretty sure the rest of the code should work…

But for the functions I gave you in my second message, I’m 100% sure it should work… I use it in almost all my sites and have it in my test installation with the last WP version. It works pretty well without the “header already sent” error. This error is not relative to the function itself.

Just repair your functions.php and add the function with a good text editor, it should work.

S.

Ok…

And here is the solution for the code using the custom field :

<?php
$image = get_post_meta($post->ID, 'thumbnail', true);
$link = get_permalink($post->ID);
if ($image == '') {
echo '';
}
else {
echo  '<a href="'.$link.'" title="'.$post->post_title.'"><img src="'.$image.'" alt="" /></a>';
}
?>

I made a mistake with the if contidition :

My mistake :
if ($image == 0)

It should be :
if ($image == '')

S.

Justin has already released plugin for this -> https://justintadlock.com/archives/2008/05/27/get-the-image-wordpress-plugin

thanks Simon J, that worked much better than what I had on one of my sites. I think the script I had was also too heavy. Now I just have to make that thumbnail link to the post which shouldn’t be too hard.