So I migrated a website of a webdesigner and he used for news-posts a custom field for images. Now I made this website and I need to change 256 posts to set a featured image since it's not working with this custom field. Does anyone know how to set a post featured image from an already made custom field?

1 Answer 1


Your question is not entirely clear, but I suppose your new theme is using featured images in the normal way, which leaves empty featured images on older posts, because they are stored in a custom field. You can catch those using the filter at the end of get_the_post_thumbnail. Because I don't know how the custom field is made I can't give complete code, but it would look like this:

add_filter ('post_thumbnail_html','wpse303106_custom_featured_image',10,5);

function wpse303106_custom_featured_image ($html, $post->ID, $post_thumbnail_id, $size, $attr) {
  if ('' == $html && test-for-existence-of-custom-field) {
    $html = ... assemble from custom field ...
  return $html;
  • Can't speak dutch in here right? well this is the old website: vledder.nu/category/nieuws I dont even know what custom field it's using. Underneath 'Nieuws' there are different images, I need the images on the left of the news as the new featured image in the posts for example.
    – mel
    Commented May 9, 2018 at 13:59
  • From the site I can't see the code that is generating the custom field. You'll have to ask the old developer. Building the filter shouldn't be more than 15 minutes work or so.
    – cjbj
    Commented May 9, 2018 at 14:03

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