Image problem for wordpress posts?

Question

WordPress

Gentlemen, help is needed, I'm making a plugin that should check if the posts have a picture or not, if it doesn't, you need to substitute another one (via the link), there is some kind of hook or filter that can be used through some kind of loop, for example, and run posts all and check + replace it if required.
I really need help I've been looking for a solution for a long time

Answer 1

See the answers here: How to loop through all the posts in the plugin?