Mello

投稿にサムネイルが設定されているかチェックします。 
サムネイルが設定されていない場合、自動でフリーの画像素材サイトからランダムで画像をダウンロードしてサムネイルに設定します。 
ダウンロードする素材サイトはpixabayです 
ダウンロードできる画像の種類は100種類前後 
負荷対策で投稿数が多い場合は時間がかかることがあります
Make sure thumbnails are set for posts. If there are no thumbnails in the post, download the image randomly from the free image material site and set it as a thumbnail. 
The image to be downloaded is acquired from pixabay. 
Pixabay is a free material site that can also be used for commercial purposes.
The image to download is random 
The downloaded image can be checked from the media. 
If there are many posts, the thumbnail images may be duplicated. 
There are about 100 images to download. 
We will execute it at regular intervals with load balancing to the server. 
Recommended environment is PHP 7.0 or higher.
<h3>Arbitrary section 1</h3>

Thumbnail_Create

記事のサムネイルを自動で作成。画像を素材サイトから自動でダウンロードします。

nosilver4u

Pedro Elsner

Force Regenerate Thumbnails allows you to delete all old images sizes and REALLY regenerate the thumbnails for your uploads.
Regenerate all thumbnails from the Tools admin menu. Regenerate batches of images via the Media Library list mode. Select the images to regenerate and then use the Bulk Actions drop-down menu to Force Regenerate Thumbnails. Use attachment actions to regenerate thumbnails for a single image.
Several filters exist for advanced usage. See more via <a href="https://gist.github.com/nosilver4u/eb858df10521aece2044a3a15ccdd17b" rel="nofollow ugc">this gist</a>.
You may report security issues through our Patchstack Vulnerability Disclosure Program. The Patchstack team helps validate, triage and handle any security vulnerabilities. <a href="https://patchstack.com/database/vdp/force-regenerate-thumbnails" rel="nofollow ugc">Report a security vulnerability.</a>

Force Regenerate Thumbnails

Delete and REALLY force thumbnail regeneration.

Thumbnail_Create vs Force Regenerate Thumbnails