How to retrieve all meta data directly from the $post object? Such as $post->related_topics?

Question

I set up a meta field related_topics that I use to associate lesson topics to a custom post type lesson.

I read here

https://stackoverflow.com/questions/19640850/wordpress-how-to-return-meta-with-query-posts

that you can access meta fields directly from a post object in the manner $post->my_field.

For a given lesson there could be several related topics. For a given lesson that has multiple topics, I noticed that $post->related_topics only returns the first topic instance, when in fact there are more than one. Is there some method to use, something like $post->related_topics->all()? Maybe with this convention only one item is returned by default even if there is a collection?

thanks, Brian

Answer 1

By calling $post->related_topics you are using the magic functions of the object ( __get and __isset )

To make it simple, behind the scenes it is the same as :

get_post_meta( $post->ID, 'related_topics', true );

So you are just abstracting the use of the function get_post_meta. And as you can see, the third argument is defined as TRUE. And this tells the function to return a single value.

So its ok if your meta is a single value, but if you have multiple values, then you must set the third argument as false. Thus you shouldn't use the magic functions, but rather call get_post_meta yourself.

So, just use :

$topics = get_post_meta( $post->ID, 'related_topics', false);

like that you have an array of values