Related posts widget - category

Question

I want to edit this widget to display related posts from the current category. This code below display only posts from a category that I must select manually. What I want to happen is that the widget shows related posts from that category. Thanks for any help

add_action( 'widgets_init', 'catposts_load_widgets' );

function catposts_load_widgets() {
    register_widget( 'Catposts_Widget' );
}

class Catposts_Widget extends WP_Widget {

    function Catposts_Widget() {
        /* Widget settings. */
        $widget_ops = array( 'classname' => 'catposts', 'description' => __('Adds posts from a specific category .', "solostream") );
        /* Widget control settings. */
        $control_ops = array( 'width' => 300, 'height' => 350, 'id_base' => 'catposts-widget' );
        /* Create the widget. */
        $this->WP_Widget( 'catposts-widget', __('Category Posts Widget', "solostream"), $widget_ops, $control_ops );
    }

    function widget( $args, $instance ) {
        global $post;
        $post_old = $post; // Save the post object.

        extract( $args );

        // If no title, use the name of the category.
        if( !$instance["title"] ) {
            $category_info = get_category($instance["cat"]);
            $instance["title"] = $category_info->name;
        }

        // Get array of post info.
        $cat_posts = new WP_Query("showposts=" . $instance["num"] . "&cat=" . $instance["cat"]);

        /* Before widget (defined by themes). */
        echo $before_widget;

        // Widget title
        echo $before_title;
        if( $instance["title_link"] )
            echo '<a href="' . get_category_link($instance["cat"]) . '">' . $instance["title"] . '</a>';
        else
            echo $instance["title"];
        echo $after_title;

        // Post list
        echo "<div class='cat-posts-widget'>\n";

        while ( $cat_posts->have_posts() )
        {
            $cat_posts->the_post();
        ?>
                <div class="post" id="catpost-<?php the_ID(); ?>">

                    <div class="entry clearfix">

                        <a href="<?php the_permalink() ?>" rel="<?php _e("bookmark", "solostream"); ?>" title="<?php _e("Permanent Link to", "solostream"); ?> <?php the_title(); ?>"><?php include (TEMPLATEPATH . "/post-thumb.php"); ?></a>

                        <p class="post-title"><a href="<?php the_permalink() ?>" rel="<?php _e("bookmark", "solostream"); ?>" title="<?php _e("Permanent Link to", "solostream"); ?> <?php the_title(); ?>"><?php the_title(); ?></a></p>

                        <?php the_excerpt(); ?>

                    </div>

                    <?php include (TEMPLATEPATH . "/postinfo.php"); ?>

                    <div style="clear:both;"></div>

                </div>
        <?php
        }

        echo "</div>\n";

        echo $after_widget;

        remove_filter('excerpt_length', $new_excerpt_length);

        $post = $post_old; // Restore the post object.
}

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

        <p>
            <label>
                <?php _e( 'Category' ); ?>:
                <?php wp_dropdown_categories( array( 'name' => $this->get_field_name("cat"), 'selected' => $instance["cat"] ) ); ?>
            </label>
        </p>

        <p>
            <label for="<?php echo $this->get_field_id("num"); ?>">
                <?php _e('Number of Posts to Show'); ?>:
                <input style="text-align: center;" id="<?php echo $this->get_field_id("num"); ?>" name="<?php echo $this->get_field_name("num"); ?>" type="text" value="<?php echo absint($instance["num"]); ?>" size='3' />
            </label>
        </p>

        <p>
            <label for="<?php echo $this->get_field_id("title_link"); ?>">
                <input type="checkbox" class="checkbox" id="<?php echo $this->get_field_id("title_link"); ?>" name="<?php echo $this->get_field_name("title_link"); ?>"<?php checked( (bool) $instance["title_link"], true ); ?> />
                <?php _e( 'Make widget title link' ); ?>
            </label>
        </p>    

    <?php
    }
}

Answer 1

Change function widget() as below

    global $post;

    // Get array of category ID's from current Post
    $post_categories = wp_get_post_categories( $post->ID );

    // Get array of post info.
    if(isset($post_categories) && is_array($post_categories) && count($post_categories) > 0){
        $cat_posts = new WP_Query("showposts=" . $instance["num"] . "&cat=" . $post_categories);    
    } else {
        $cat_posts = new WP_Query("showposts=" . $instance["num"] . "&cat=" . $instance["cat"]);    
    }

Answer 2

So you want to display posts that are in the 'current category'. This is doable, but you need to think about what you're going to do when there isn't a 'current category' - for instance on index.php. You'll need to decide what to do on a single page as well - do you take a category from the currently viewed post.

The following queries posts:

• In the same category, when viewing a category,
• In some category belonging to the post when viewing a single post
• Otherwise, does not restrict by category

Note showposts is deprecated, use posts_per_page instead:

$args = array(
   'posts_per_page'=>$instance["num"],
);

if( is_category() ){
    $args['cat'] = get_queried_object_id();

}elseif( is_singular() || is_single() ){
    $cats = get_the_terms(get_the_ID(),'category');
    if( $cats ){
       $cat = array_pop($cat);
       $args['cat'] = (int) $cat->term_id;
    }
}

 $cat_posts = new WP_Query($args);