How to use external link images as article thumbnails in WordPress

Ideas:

1. There must be a way to determine the image address: the first image in the article, or use a custom column Add a custom value.

2. Call the determined picture in the foreground: use the function method or call the picture directly.

The implementation is as follows:

Premise:

It is best for any call to be in a LOOP loop, so that it can be easily Use $post value.

1. Call the first picture in the article: use $post->post_content to get the article content, and then use the matching method to get the src value of the first picture.

preg_match(&#39;/<img.+src=[\&#39;\"]([^\&#39;\"]+)[\&#39;\"].* \/>/i&#39;,$post->post_content,$index_piclink);
if(count($index_piclink) >= 2)$image_src = $index_piclink[1];
if(!strstr($image_src,&#39;http://&#39;))$image_src = false;

2. Call a custom column: When writing an article, add a custom column with the noun post_thumb, and then create it using the address of the image as the value. For example, meta_key:post_thumb,meta_value:http://www.utubon.com/images/logo.png, and then call it through the following method:

$image_src = get_post_meta($post->ID,'post_thumb',true);
$image_src = trim($image_src) !== '' ? trim($image_src) : false;

3. In the article loop Use them

if($image_src)echo &#39;<img src="&#39;.$image_src.&#39;" />&#39;;

4. Make them into functions

function get_thumb_src($size = 'thumbnail',$first_pic_in_ctonte = true){
global $post;
$image_src = '';
if(function_exists('has_post_thumbnail') && has_post_thumbnail()){
$image_id = get_post_thumbnail_id();
$image_src = wp_get_attachment_image_src($image_id,$size);
$image_src = $image_src[0];
}else{
$image_src = get_post_meta($post->ID,'post_thumb',$single=true);
if(!$image_src && $first_pic_in_ctonte){
preg_match(&#39;/<img.+src=[\&#39;\"]([^\&#39;\"]+)[\&#39;\"].* \/>/i&#39;,$post->post_content,$index_piclink);
if(count($index_piclink) >= 2)$image_src = $index_piclink[1];
if(!strstr($image_src,&#39;http://&#39;))$image_src =false;
}
}
return $image_src;
}
function the_thumb_src($size = &#39;thumbnail&#39;,$first_pic_in_ctonte = true){
echo get_thumb_src($size,$first_pic_in_ctonte);
}

This function (put it in functions.php) implements the selection of article thumbnails. If there is already a featured image, use the featured image. If not, check the post_thumb custom column. If there is no featured image, use the first image of the article. If the article does not have an image, return a false value. When using it, it is as follows:

if(get_thumb_src())the_thumb_src();

Recommended tutorial: wordpress tutorial

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