How do I query a custom post type with a custom taxonomy?

i am using this query to fetch custom posts (FAQs Posts) with its custom taxonomy (faq_category). since {taxonomy} parameter in WP_Query args was deprecated since v.3.1 and introduced {tax_query}. below is the code that works perfectly.

$query = new WP_Query( array(
    'post_type' => 'faqs',          // name of post type.
    'tax_query' => array(
        array(
            'taxonomy' => 'faq_category',   // taxonomy name
            'field' => 'term_id',           // term_id, slug or name
            'terms' => 48,                  // term id, term slug or term name
        )
    )
) );

while ( $query->have_posts() ) : $query->the_post();
    // do stuff here....
endwhile;

/**
 * reset the orignal query
 * we should use this to reset wp_query
 */
wp_reset_query();

Here the code that works like magic. I am fetching all posts for the custom post_type “university_unit” with custom taxonomy “unit_type” and multiple taxonomy terms as “directorate” and “office”.
I hope it helps out.

<?php
$args = array(
    'post_type' => 'university_unit',
    'posts_per_page' => -1,
    'orderby' => 'title',
    'order' => 'ASC',
    'tax_query' => array(

        array(
            'taxonomy' => 'unit_type',
            'field' => 'slug',
            'terms' => array('directorate', 'office')
        )

    )
);

$Query = new WP_Query($args);
if($Query -> have_posts()):

    while($Query -> have_posts()):
        $Query -> the_post();
        ?>
        <div class="cm-post-list-item">
            <article>
                <div class="cm-post-head">
                    <h3 class="cm-text-blue">
                        <a href="https://wordpress.stackexchange.com/questions/84921/<?php the_permalink(); ?>"><?php the_title();?></a>
                    </h3>
                </div>
                <div class="cm-post-body"><?php the_excerpt();?></div>
            </article>
        </div>
        <?php
    endwhile;

else:
    "No Administrative Offices Found. Try again later";
endif;
wp_reset_postdata();
?>

This helped me to get all posts listed under each term for custom taxanomy for CPT

    <?php
    // Get list of all taxonomy terms  -- In simple categories title
    $args = array(
                'taxonomy' => 'project_category',
                'orderby' => 'name',
                'order'   => 'ASC'
            );
    $cats = get_categories($args);

    // For every Terms of custom taxonomy get their posts by term_id
    foreach($cats as $cat) {
        ?>
        <a href="https://wordpress.stackexchange.com/questions/84921/<?php echo get_category_link( $cat->term_id ) ?>">
            <?php echo $cat->name; ?> <br>
            <?php // echo $cat->term_id; ?> <br>
        </a>


            <?php
                // Query Arguments
                $args = array(
                    'post_type' => 'portfolio', // the post type
                    'tax_query' => array(
                        array(
                            'taxonomy' => 'project_category', // the custom vocabulary
                            'field'    => 'term_id',          // term_id, slug or name  (Define by what you want to search the below term)    
                            'terms'    => $cat->term_id,      // provide the term slugs
                        ),
                    ),
                );

                // The query
                $the_query = new WP_Query( $args );

                // The Loop
                if ( $the_query->have_posts() ) {
                    echo '<h2> List of posts tagged with this tag </h2>';

                    echo '<ul>';
                    $html_list_items="";
                    while ( $the_query->have_posts() ) {
                        $the_query->the_post();
                        $html_list_items .= '<li>';
                        $html_list_items .= '<a href="' . get_permalink() . '">';
                        $html_list_items .= get_the_title();
                        $html_list_items .= '</a>';
                        $html_list_items .= '</li>';
                    }
                    echo $html_list_items;
                    echo '</ul>';

                } else {
                    // no posts found
                }

                wp_reset_postdata(); // reset global $post;

                ?>

    <?php } ?>

This answer now is not valid anymore since wordpress changes their taxonomy parameter information. please use this way. It will work. It works for me. “tax_query” replaces with “tax”. hope it will work.

$the_query = new WP_Query( array(
    'post_type' => 'Adverts',
    'tax' => array(
        array (
            'taxonomy' => 'advert_tag',
            'field' => 'slug',
            'terms' => 'politics',
        )
    ),
) );

while ( $the_query->have_posts() ) :
    $the_query->the_post();
    // Show Posts ...
endwhile;

/* Restore original Post Data 
 * NB: Because we are using new WP_Query we aren't stomping on the 
 * original $wp_query and it does not need to be reset.
*/
wp_reset_postdata();