Why query by specific date with variables doesn't return same result that with harcoded integers?

Question

Having a blog with one post per day from monday to friday, on weekends I need to retrieve last friday post if user click the "today word" or the las thursday post if user click the "yesterday word".

I have registered a query var with this code:

 function register_query_vars ($vars) {
        $vars[] = 'dia';
        return $vars;
    }
    add_filter('query_vars','register_query_vars'); 

And I have a link for "today word" that has this url:

http://wordsexample.com/?dia=today;

Then, in the pre_get_posts filter I make the query with the result of a function that return an array with the year, month and day that exactly I need (depending on the day of week and the var queried: today or yesterday).

Well, the problem is that if I hardcode the integer or string values of year, month and day in the set_query_var the query returns de post I want, but if I put variables then the query return all posts from the date passed, and I want only the post of the desired day.

This code runs:

function limit_posts_per_archive_page($query) {
    if (!is_admin() && $query->is_main_query()){
        if(get_query_var('dia') != ''):  
            set_query_var('posts_per_page', 1);
            set_query_var('posts_per_archive_page', 1); 
            set_query_var('post_type','post');
            set_query_var('post_status','publish');
            set_query_var( 'year', 2015 );
            set_query_var( 'month', 1 );
            set_query_var( 'day', 23 );
        elseif (is_home()) :
            $query->set('posts_per_page', 10);
        endif;
    }
}
add_filter('pre_get_posts', 'limit_posts_per_archive_page');

This code doesn't run:

function limit_posts_per_archive_page($query) {
    if (!is_admin() && $query->is_main_query()){
        if(get_query_var('dia') != ''): 
            $dies = dies_consulta(); //returns array with the needed date
            $anyet = $dies['year'];
            $meset = $dies['month'];
            $diet = $dies['day'];
            set_query_var('posts_per_page', 1);
            set_query_var('posts_per_archive_page', 1); 
            set_query_var('post_type','post');
            set_query_var('post_status','publish');
            set_query_var( 'year', $anyet );
            set_query_var( 'month', $meset );
            set_query_var( 'day', $diet );
        elseif (is_home()) :
            $query->set('posts_per_page', 10);
        endif;
    }
}
add_filter('pre_get_posts', 'limit_posts_per_archive_page');

I have tested with also with query->set form, but it doesn't matter, if I hardcode the data no problem, if I put the variables it doesn't run.

$query->set('date_query', array(                                        
    array(
            'year'  => $anyet,
            'monthnum' => $meset,
            'day'   => $diet,
        ),
    ));

or:

$query->set('date_query', array(    
    array(
            'year'  => $dies['year'],
            'month' => $dies['mon'],
            'day'   => $dies['mday'],
        ),
    ));

I'm sure I'm missing something but I can't understand why is this different, and no correct, behaviour with variables.

Any idea or suggestion will be very glad.

Answer 1

I believe your problem is that you are not casting the variables over into integers. You should give this a try:

$query->set('date_query', array(    
    array(
        'year'  => (int)$dies['year'],
        'month' => (int)$dies['mon'],
        'day'   => (int)$dies['mday'],
    ),
));

or if you would like, before you even set up the arguments for the query, you could do something along the lines of:

$anyet = intval( $dies['year'] );

The query value is supposed to be an integer for the day, year, month keys. So most likely since you are getting query vars from the url, which are strings, if that is the only thing changed from the staticly built working query to the dynamically built query, then I believe you should be good if you cast those strings into integers using (int) or intval(). Here is an excellent resource on query string arguments by Bill Erickson, I use it often, has saved me many times.

http://www.billerickson.net/code/wp_query-arguments/