Internet does not have a solution for this specific condition. First I create a new post as below:
After that my lovely meta field appear on the edit screen of post. I can populate it by hand. Save or use its all ok. Untill now there is no problem.
But when I use the code below it just removes my lovely meta field from the post edit screen. But at the frontend(post template), I am able to ask for the metafields of the post and display them correctly with proper unserializations. Problem is, I want to see my lovely meta field on the “post edit” page as a lovely string or etc. (wp-admin/post.php action=edit)
How can I make them editable from post edit page.