get data match with extra field value using wp_query for custom post

Question

I added post_meta 'batch' to 'assignment' custom post as follows:

update_post_meta( $id, 'batch', strip_tags($_POST['batch']));

Now I am trying to retrieve this data as follows:

$args = array(
    'post_type'   => 'assignment',
    'post_status' => 'publish',
);

$assignments = new WP_Query( $args );

I want to get all data having 'batch=2017'. How can I do this?

Answer 1

Change your WP Query arguments like this:

$args = array(
    'post_type'   => 'assignment',
    'post_status' => 'publish',
    'meta_key'     => 'batch',
    'meta_value'   => '2017',
);

For multiple post meta you can use meta_query like this

$args = array(
    'post_type'   => 'assignment',
    'post_status' => 'publish',
    'meta_query' => array(
        array(
            'key'     => 'color',
            'value'   => 'blue',
        ),
        array(
            'key' => 'year',
            'value' => '2017',
        )
    ),
);

Answer 2

First of all, creating a custom taxonomy named "batch" and creating required terms with it would have made this very easy.

$args = array(
    'post_type'   => 'assignment',
    'post_status' => 'publish',
);

$assignments = new WP_Query( $args );

if ( $assignments->have_posts() ) {

    while ( $assignments->have_posts() ) {
            $assignments->the_post();
           $batch = get_post_meta( get_the_ID(), 'batch', true );
           if($batch == 2017){
              echo get_the_title();
           }
    }

}