Do a custom query search in wordpress by post meta - wordpress

Question

I'm doing a custom search in wordpress, and I would like to find my custom type articles by searching them from custom meta keys.
This code filters posts by custom types, but filters all of them by custom metas, showing no results!
function filtri_di_ricerca( $query ) {
if ( is_admin() || ! $query->is_main_query() )
return;
if (is_home())
{
$query->set('post_type', 'post_annunci');
$query->set('posts_per_page', 1000);
$meta_query = array();
// Only check these form fields
$fields = array( 'annuncio_contratto', 'annuncio_categorie', 'annuncio_tipologia', 'annuncio_citta', 'annuncio_prezzo');
foreach( $fields as $field ) {
if( $_GET[$field] != '' ) {
// We have something to match, otherwise ignore the field...
$meta_query[] = array(
'key' => $field,
'value' => $_GET[$field],
'compare' => '='
);
}
}
$meta_query['relation'] = 'AND';
$query->set('meta_query',$meta_query);
}
return;
}
add_action( 'pre_get_posts', 'filtri_di_ricerca');
The search address is:
http://example.com/?annuncio_contratto=Vendita&annuncio_categorie=Residenziale&annuncio_tipologia=Appartamento&annuncio_citta=NewYork
DEBUG with:
echo "<pre>"; print_r($wp_query->query_vars); echo "</pre>";
result:
Array
(
[error] =>
[m] => 0
[p] => 0
[post_parent] =>
[subpost] =>
[subpost_id] =>
[attachment] =>
[attachment_id] => 0
[name] =>
[static] =>
[pagename] =>
[page_id] => 0
[second] =>
[minute] =>
[hour] =>
[day] => 0
[monthnum] => 0
[year] => 0
[w] => 0
[category_name] =>
[tag] =>
[cat] =>
[tag_id] =>
[author_name] =>
[feed] =>
[tb] =>
[paged] => 0
[comments_popup] =>
[meta_key] =>
[meta_value] =>
[preview] =>
[s] =>
[sentence] =>
[fields] =>
[menu_order] =>
[category__in] => Array
(
)
[category__not_in] => Array
(
)
[category__and] => Array
(
)
[post__in] => Array
(
)
[post__not_in] => Array
(
)
[tag__in] => Array
(
)
[tag__not_in] => Array
(
)
[tag__and] => Array
(
)
[tag_slug__in] => Array
(
)
[tag_slug__and] => Array
(
)
[post_type] => post_annunci
[posts_per_page] => 1000
[meta_query] => Array
(
[0] => Array
(
[key] => annuncio_contratto
[value] => Vendita
[compare] => =
)
[1] => Array
(
[key] => annuncio_categorie
[value] => Residenziale
[compare] => =
)
[2] => Array
(
[key] => annuncio_tipologia
[value] => Appartamento
[compare] => =
)
[3] => Array
(
[key] => annuncio_citta
[value] => Pesaro
[compare] => =
)
[relation] => AND
)
[ignore_sticky_posts] =>
[suppress_filters] =>
[cache_results] => 1
[update_post_term_cache] => 1
[update_post_meta_cache] => 1
[nopaging] =>
[comments_per_page] => 50
[no_found_rows] =>
[order] => DESC
)

Answer 1

function filtri_di_ricerca( $query ) {
if ( is_admin() || ! $query->is_main_query() )
return;
if (is_home())
{
$query->set('post_type', 'post_annunci'); // added
$query->set('posts_per_page', 1000); //added
$meta_query = array(); //edited
// Only check these form fields
$fields = array( 'annuncio_contratto', 'annuncio_categorie', 'annuncio_tipologia', 'annuncio_citta', 'annuncio_prezzo');
foreach( $fields as $field ) {
if( isset($_GET[$field]) and $_GET[$field] != '' ) { // ADDED isset()
// We have something to match, otherwise ignore the field...
$meta_query[] = array(
'key' => $field,
'value' => $_GET[$field],
'compare' => '=', // CHANGED
);
}
}
$meta_query['relation'] = 'AND'; // ADDED
$query->set('meta_query',$meta_query);
}
return;
}
add_action( 'pre_get_posts', 'filtri_di_ricerca');
EDIT
You went wrong when you put main query data and meta query data in the same basket.