Automatically tag posts based on user-defined words [closed]

Question

1. I want to systematically add tags (/custom taxonomy terms) to all previous posts, from a predefined set of tags (i.e., not Yahoo tags or tags from 3rd-party APIs).

2. For future posts, I would like tags to be either suggested or added based on the content of posts.

3. Ideally: I would like a more customized way of recommending/adding tags than simply looking for the tag text in an entry; ideally I'd be able to specify a set of related words (such as with a term meta field) so that, for example, a tag of Education is added not just when "education" appears in a post but when some of a specified list appear in the post: teachers, school, standardized tests, math, etc.

Can you recommend a plugin or strategy that would help achieve this?

I'm open to ideas both simple and complex.

Answer 1

I wouldn't call myself an expert so test what I'm offering, but you may try to add a hook when you publish the post that uses a preg_match (or similar function) to find those terms in the post content. Then, based on what you found you could add the wp_set_post_terms.