Is it possible to define the data type of a Custom Field?

Question

I am adding a new "Custom Post Type" named "Seminar". I am defining three custom fields

1. Location
2. StartTime
3. EndTime

StartTime and EndTime are going to store dates (surprise, surprise). I am wondering if there's any way to tell WordPress to treat these like dates so that I can sort by them and stuff.

I am very new to WP, so forgive me if this is a dumb question.

Answer 1

Hia.

Basically no. But, you can order by meta_value in WP_Query, so you can sort. I am not sure what format you are storing the dates as, but it will need to be something that MySQL can order by, a simple Unix timestamp would be fine, you would do:

$query = new WP_Query( 'post_type=seminar&meta_key=start_time&meta_value=' . time() .  '&meta_compare=>' );

Would get all the seminars with a start date after "now"

Answer 2

The custom field value is stored as is - and I think you can use Joe's answer to get the posts, however to "sort" using start time you might need to use something like this:

$posts = query_posts($query_string. '&orderby=meta_value&meta_key=start_time&order=DESC' );

There is a plug-in called more fields, that I think will let you do this without writing code. You can add a new input box only to your custom post type, then select date under advanced options.