I came across the need today to modify page/post titles – adding in some custom meta data from a metabox on the post/page. I did not want to have to modify the page template in the theme to add this extra data, so I looked about using WordPress’s the_title filter.
At first, I just used this filter blanket-style, without thinking about the need for conditionals. This worked great until I realized it was modifying the title in loops as well as the single page/post view.
This was not the desired functionality, so I began looking for a way to perform the intended behavior. I had recently watched Andrew Nacin’s talk, You don’t know query, in which he mentioned is_main_query as a way of detecting if we were in the main loop. However, we don’t have a $query variable to work with inside the the_title filter. In fact, all we have to use is the $title (and obviously the $post). What do to?
Add an action of course! I settled on using loop_start, based on this (old) discussion on WP Hackers. My code ended up looking like this:
This afforded me the ability to use the query variables more appropriately, checking if the $array is indeed $wp_query. Ironically, this solution resorts to the very code that is_main_query was supposed to deprecate.
If you ever need to filter the title only in certain cases, consider doing so through an action hook instead of directly – this way you can utilize the variables you may need.w