Using wp_dropdown_categories in widget options

Question

I have a product search widget when you select certain products a hidden field is shown. I would like to set a custom category in my widget options that is then used for displaying my hidden field.

I have the front end working 100% when I add the parent category_id manually to my code. Now I just need to set the category option in my back end.

This is what I have currently but its not working in the sense that its not storing the selection that is made. I left out the search form because it doens't use any of the widget options.

class Equipment_Search extends WP_Widget {

    function Equipment_Search() {
        $widget_ops = array( 'classname' => 'agriquip', 'description' => __('Displays the Equipment Search Form', 'agriquip') );
        $control_ops = array( 'width' => 200, 'height' => 350, 'id_base' => 'agriquip-widget' );
        $this->WP_Widget( 'agriquip-widget', __('Equipment Search', 'agriquip'), $widget_ops, $control_ops );
    }

    function widget( $args, $instance ) {
        extract( $args );

        $title = apply_filters('widget_title', $instance['title'] );
        $tract_id = isset( $instance['exc_equipment_cat'] ) ? $instance['exc_equipment_cat'] : false;   
        $tract = wp_list_pluck(get_terms('exc_equipment_cat', array('parent' => 3)), 'slug');
        $tractparent = get_term_by('id','3', 'exc_equipment_cat');
        $tractparent = $tractparent->slug; 


        echo $before_widget;
echo $after_widget;
    }

    function update( $new_instance, $old_instance ) {
        $instance = $old_instance;

        //Strip tags from title and name to remove HTML 
        $instance['title'] = strip_tags( $new_instance['title'] );
        $instance['exc_equipment_cat'] = $new_instance['exc_equipment_cat'] ? 1 : 0;

        return $instance;
    }

    function form( $instance ) {

        //Set up some default widget settings.
        $defaults = array( 'title' => __('Equipment Search', 'agriquip'), 'exc_equipment_cat' => '-1');
        $instance = wp_parse_args( (array) $instance, $defaults ); ?>

        <p>
            <label for="<?php echo $this->get_field_id( 'title' ); ?>"><?php _e('Title:', 'agriquip'); ?></label>
            <input id="<?php echo $this->get_field_id( 'title' ); ?>" name="<?php echo $this->get_field_name( 'title' ); ?>" value="<?php echo $instance['title']; ?>" class="widefat" />
        </p>

            <form method="post" action="">
                <label for="exc_equipment_cat">Category to use with Kw Options</label>
                <?php
                        $dropdown_args = array(
                            'taxonomy'          => 'exc_equipment_cat',
                            'name'              => $this->get_field_name('exc_equipment_cat'),
                            'show_count'        => 1,
                            'orderby'           => 'name',
                            'hierarchical'      => true,
                            'echo'              => 0,
                            'depth'             => 1,
                            'show_option_none'  => 'Select Category',
                            'selected'          => (int)$instance['exc_equipment_cat'],
                            );
                        wp_dropdown_categories(apply_filters('widget_categories_dropdown_args', $dropdown_args));
                        $select = wp_dropdown_categories(apply_filters('widget_categories_dropdown_args', $dropdown_args));
                        $select = preg_replace("#<select([^>]*)>#", "<select$1 class='widefat'>", $select);
                    echo $select;
                ?>  
            </form>


    <?php
    }

Answer 1

I got it :-) thanks to this

function update( $new_instance, $old_instance ) {
        $instance = $old_instance;

        //Strip tags from title and name to remove HTML 
        $instance['title'] = strip_tags( $new_instance['title'] );
        $instance['kwtax'] = strip_tags( $new_instance['kwtax'] );

        return $instance;
    }

    function form( $instance ) {

        //Set up some default widget settings.
        $defaults = array( 'title' => __('Equipment Search', 'agriquip'), 'kwtax' => '');
        $instance = wp_parse_args( (array) $instance, $defaults );
        ?>
        <p>
            <label for="<?php echo $this->get_field_id( 'title' ); ?>"><?php _e('Title:', 'agriquip'); ?></label>
            <input id="<?php echo $this->get_field_id( 'title' ); ?>" name="<?php echo $this->get_field_name( 'title' ); ?>" value="<?php echo $instance['title']; ?>" class="widefat" />
        </p>

          <p>
            <select id="<?php echo $this->get_field_id('kwtax'); ?>" name="<?php echo $this->get_field_name('kwtax'); ?>" class="widefat" style="width:100%;">
                <?php foreach(get_terms('exc_equipment_cat','parent=0&hide_empty=0') as $term) { ?>
                <option <?php selected( $instance['kwtax'], $term->term_id ); ?> value="<?php echo $term->term_id; ?>"><?php echo $term->name; ?></option>
                <?php } ?>      
            </select>
        </p>

Answer 2

You can use wp built-in function see code below.

 <?php 
    $args = array(
                    'name'             => $this->get_field_name('category'),
        'show_option_none' => __( 'Select category' ),
        'show_count'       => 1,
        'orderby'          => 'name',
        'echo'             => 0,
                    'selected'         => $category,
                    'class'            => 'widefat'
    );
            echo wp_dropdown_categories($args);
        ?>

Answer 3

Thank you HaneD.

Your example is probably the only example that I could find that works. If someone else wants to get it to work without making a custom category try to replace:

<?php foreach(get_terms('exc_equipment_cat','parent=0&hide_empty=0') as $term) { ?>

with

<?php foreach(get_terms('category','parent=0&hide_empty=0') as $term) { ?>

Answer 4

You were so close, all you had to do was find your category ID from the update method. Like so:

    $instance['exc_equipment_cat'] = filter_var($new_instance['exc_equipment_cat'], FILTER_SANITIZE_NUMBER_INT);

Or however you want to sanitize the number coming from the update.

And that will give you the category or taxonomy id.