Changing search criteria

Ciao sacconi,

I tested your code on my site. I added a custom field named “function_name” to a post, with a value of “Rif. 305”. I then made a generic search request like so: https://my-test-site.com/?s=305
This worked as expected and the related post was found. Your problem lies elsewhere.

I suspect the $meta_query = array('relation' => 'OR'); is not having the effect you think it should. This applies OR logic only to other meta queries, it does not apply OR logic to other search criteria such as taxonomies, titles, and what not. As you have no other meta queries, this line is ineffective, other than it establishes an array to push more data into. 'relation' => 'OR' is harmless to exist, but it does nothing when only one meta value is specified.

Your code results in a SQL query that in part is:

WHERE 1=1
AND ( ( wp_postmeta.meta_key = 'function_name'
AND wp_postmeta.meta_value LIKE '%305%' ) )
AND ((wp_posts.post_type = 'post'
AND (wp_posts.post_status = 'publish'

All ANDs, no ORs! (there are other ORs in search queries, but not related to post meta) If you had other post meta criteria besides “function_name”, then those would be ORed, but only in relation to post meta, not other criteria.

You maybe want the first AND in the above SQL snippet to instead be OR? This is not easy to accomplish with WP_Query. You’d need to use the “posts’request” filter to search for the correct AND and replace only that instance with OR. Similar to “pre_get_posts”, all sorts of queries pass through “posts_request”. You must ensure you’re only altering the query that is supposed to be altered. For example by verifying there’s an “s” query var.

I’m not convinced you want OR logic, but its lack would explain why searches are not working as you want. With OR logic, you tend to get more matches when multiple criteria is applied. With AND logic you get fewer or no matches. If you want matches that fit all the supplied criteria, use AND logic. For matches to only fit some of the criteria, then OR logic is called for. However, with OR logic you’ll more likely get poor quality matches. You might get a property whose function_name meta is Rif. 305, but none of the other criteria like 4 persons or 3 bedrooms may be present.

The SQL clause wp_postmeta.meta_value LIKE '%305%' ) ) should match any meta value that has “305” in it, no matter what else comes before or after. Should match “Rif 305” or “305” or “305 foo” or “Rif 305 foo”. The % in SQL is a wildcard character, much like * in many computer operating systems. Something else is amiss besides the code you linked to in your OP.

It might have something to do with how your form sanitizes input maybe? Just guessing.