如何获得在WordPress多选框（wp_dropdown_categories）中预先选择的值？

Question

I am trying to get the following wp_dropdown_categories call to pre select values based on what the user has submitted before. This is part of a larger user profile edit form. The values are pulled in just fine but are not being automatically highlighted if they were selected previously. Any help would be appreciated!! job_ind_pref_call=custom user profiel field.

</label> <?php
    $sel = 0;
    $sel1 = get_user_meta($user_ID, 'job_ind_pref_call', true);
    if(isset($_POST['job_ind_pref_call'])) {

        $sel1 = $_POST['job_ind_pref_call'];
    }
    if (isset($posted['job_term_cat']) && $posted['job_term_cat']>0) $sel = $posted['job_term_cat'];
    global $featured_job_cat_id;
    $args = array(
        'orderby'            => 'name',
        'exclude'            => 3,
        'order'              => 'ASC',
        'name'               => 'job_ind_pref_call[]',
        'hierarchical'       => 1,
        'echo'               => 0,
        'class'              => 'job_cat',
        'selected'           => $sel1,
        'taxonomy'           => 'job_cat',
        'hide_empty'         => false
    );


    $dropdown = wp_dropdown_categories( $args );
    $dropdown = str_replace('class=\'job_cat\' >','class=\'job_cat\' multiple="multiple" size="6" onClick=GetMDDselections("job_ind_pref_call") ><option value="">'.__('Select a Line&hellip;', 'colabsthemes').'</option>',$dropdown);
    echo $dropdown;
?> </p>

Answer 1

First of all, the WordPress crew recommends that you use wp_category_checklist() for multiple values.

If you still persist to use wp_dropdown_categories() you must be prepared to use an.. ehum, unofficial way to make the selected options work.

Here's what you need to do:

1- Pass a new custom argument AND a new Walker class (we'll define it in step 2) to the wp_dropdown_categories() function. Let's say we call the function as such:

<?php 
wp_dropdown_categories( array( 
    '_selected' => $selected_cats_arr, 
    'walker' => 'CategoryDropdownMultiple'
) ); 
?>

2- Create a new Walker class that is configured to select the option based on our new custom argument. The code for the Walker is based on Walker_CategoryDropdown defined in wp-includes/category-template.php .

<?php
class Walker_CategoryDropdownMultiple extends Walker {
    var $tree_type = 'category';

    var $db_fields = array ('parent' => 'parent', 'id' => 'term_id');


    function start_el( &$output, $category, $depth, $args, $id = 0 ) {
        $pad = str_repeat('&nbsp;', $depth * 3);

        $cat_name = apply_filters('list_cats', $category->name, $category);
        $output .= "\t<option class=\"level-$depth\" value=\"".$category->term_id."\"";

        // HERE IS THE ONLY CHANGE FROM THE ORIGINAL FILE
        // We check our custom parameter which is an array instead of a single value.
        if ( isset( $args['_selected'] ) && in_array( $category->term_id, $args['_selected'] ) )
            $output .= ' selected="selected"';
        $output .= '>';
        $output .= $pad.$cat_name;
        if ( $args['show_count'] )
            $output .= '&nbsp;&nbsp;('. $category->count .')';
        $output .= "</option>\n";
    }
}
?>

---

Notes:

• The reason for why we can't use the original selected argument is that it's expected to be a single value in wp_dropdown_categories() and beyond.
• Note that because we're using a custom argument for the selected options then native functionality such as automatically selecting the options given with the *show_option_all* and *show_option_none* arguments won't work.