Search - Only search for post meta field

Question

I know there are a lot of good plugins which extend the wordpress search but I want to do the opposite. I want the search only to return posts which have a certain value in a certain post meta field.
How do I do that?

Answer 1

I'm not quite sure this is what you want (because it is so ... easy), but all you need to do is add the following inputs to your search form:

<input type="hidden" id="meta_key" name="meta_key" value="YOUR-META-KEY">
<input type="hidden" id="meta_value" name="meta_value" value="YOUR-META-VALUE">

Or, if you want to trigger the search by hand, do it like so:

$search = new WP_Query(array(
    's' => 'YOUR-KEYWORD(S)',
    'meta_key' => 'YOUR-META-KEY',
    'meta_value' => 'YOUR-META-VALUE'
));

// EDIT
If you're dealing with a more complex setup, you might want to use a meta_query:

$search = new WP_Query(array(
    's' => 'YOUR-KEYWORD(S)',
    'meta_query' => array(
        'key' => 'YOUR-META-KEY',
        'value' => 'YOUR-META-VALUE'
    )
));

Or even

$search = new WP_Query(array(
    's' => 'YOUR-KEYWORD(S)',
    'meta_query' => array(
        array(
            'key' => 'YOUR-FIRST-META-KEY',
            'value' => 'YOUR-FIRST-META-VALUE'
        ),
        array(
            'key' => 'YOUR-SECOND-META-KEY',
            'value' => 'YOUR-SECOND-META-VALUE'
        )
    )
));