How do I query by post format in WordPress 3.1

Question

I am trying to query for all posts with a post format of 'quote.' I have added the post formats to my functions.php with

add_theme_support( 'post-formats', array( 'image', 'video', 'gallery', 'quote' ) );

I have selected 'quote' as the format for the post in the admin. The last example under Taxonomy_Parameters shows how to display posts that have the 'quote' format but when I run it in my theme no posts are returned. Here is the code:

$args = array(
  'tax_query' => array(
    array(
      'taxonomy' => 'post-format',
      'field' => 'slug',
      'terms' => 'post-format-quote'
    )
  )
);
query_posts( $args );

When I just query all posts and place

echo get_post_format();

in the loop it returns the word 'quote' on the front-end. Also, when I var_dump() the query I do not see anything in the array about post format.

Does anyone know if it is possible to query by post format? If so how?

EDIT - See 5 comment under Bainternet's answer: This is the code found on index.php of the twentyten theme of a fresh install trying to return format type quotes. I return 'no' instead of 'quote'. Can you see anything that I should change.

get_header(); ?>
<div id="container">
  <div id="content" role="main">
    <?php $args = array(
      'tax_query' => array(
        array(
          'taxonomy' => 'post-format',
          'field' => 'slug',
          'terms' => array('quote')
        )
      )
    );
    query_posts( $args );
    if ( have_posts() ) : while ( have_posts() ) : the_post();
      echo get_post_format();
    endwhile; else:
      echo 'no';
    endif;
    wp_reset_query();      
    ?>
  </div><!-- #content -->
</div><!-- #container -->
<?php get_sidebar(); ?>
<?php get_footer(); ?>

EDIT 2 - It appears that the WordPress Codex has now changed and the portion on Taxonomy Parameters is only found in Google cache.

EDIT 3 - FINAL WORKING CODE

$args = array(
  'tax_query' => array(
    array(
      'taxonomy' => 'post_format',
      'field' => 'slug',
      'terms' => 'post-format-quote'
    )
  )
);
query_posts( $args );

The twenty-ten edit from the first edit will be...

get_header(); ?>
<div id="container">
  <div id="content" role="main">
    <?php $args = array(
      'tax_query' => array(
        array(
          'taxonomy' => 'post_format',
          'field'    => 'slug',
          'terms'    => 'post-format-quote'
        )
      )
    );
    query_posts( $args );
    if ( have_posts() ) : while ( have_posts() ) : the_post();
      the_title();
      echo get_post_format();
      echo '<br />';
    endwhile; else:
      echo 'no';
    endif;
    wp_reset_query();      
    ?>
  </div><!-- #content -->
</div><!-- #container -->
<?php get_sidebar(); ?>
<?php get_footer(); ?>

Answer 1

This code is incorrect! You have

'taxonomy' => 'post-format'

But it really needs to be:

'taxonomy' => 'post_format'

Without the underscore, the query will be invalid. I just tested this on my WordPress 3.1 install after pulling my hair out for hours.

Hope that helps!!

Answer 2

in tax_query "terms" accepts array so you need to put post-format-quote in an array like this:

$args = array(
  'tax_query' => array(
    array(
      'taxonomy' => 'post-format',
      'field' => 'slug',
      'terms' => array('post-format-quote')
    )
  )
);
query_posts( $args );