WordPress Featured Posts using Nivo Slider

Today we will look in to how to create a wordpress featured posts slider using Nivo Slider. If you have a wordpress based blog or website, you may wish to highlight a set of interesting posts of your blog or website on your homepage. You may have already searched for a wordpress plugin to do that. But this can be done without using a plugin.

First, we will look in to creating a input to select the wordpress posts that to be included in to the Featured posts slider.

All the below codes should go inside your theme’s functions.php file.

Create option to select posts for Featured Slider

Source code



add_action("admin_init", "selection_meta_box");


 


function selection_meta_box(){


add_meta_box("featured-post", "Set Featured", "featured_post", "post", "side", "low");


}


 


function featured_post(){


global $post;


$meta_data = get_post_custom($post->ID);


$featured_post = $meta_data["_featured_post"][0];


$selected = ($meta_data["_featured_post"][0] == "yes") ? 'checked' : '';


echo "<p>";


echo "<input $selected type='checkbox' name='featured_post' value='yes' />";


echo "<label>Select this post as Featured.</label>";


echo "</p>";


}

This will create a meta box inside the post editor with a checkbox option to choose which posts need to be included in to Featured posts slider.

What if you want this option also for your Custom Post types? Simply change the post type parameter in the add_meta_box function.

Source code



//change post-type to your custom post type


add_meta_box("featured-post", "Set Featured", "featured_post", "post-type", "side", "low");

Or if you want to enable this option to all your post types,

Source code



$post_types_array = get_post_types();


foreach ( $post_types_array as $post_type ) {


add_meta_box("featured-post", "Set Featured", "featured_post", $post_type, "side", "low");


}

Now we need to save the selected posts in to the database.

Source code



add_action('save_post', 'save_post_details');


 


function save_post_details(){


global $post;


if ( defined( 'DOING_AUTOSAVE' ) && DOING_AUTOSAVE )


return;


$featured_post = trim($_POST["featured_post"]);


update_post_meta($post->ID, "_featured_post", $featured_post);


}

Adding post thumbnail support to the theme

Source code



add_theme_support( 'post-thumbnails' );


if ( function_exists( 'add_image_size' ) ) {


add_image_size( 'sliding-images', 800, 400, true );


}

The function add_image_size() will create a separate custom sized image for our slider.
Note: You need to set a featured image using the “Featured image” feature by wordpress. Otherwise, the slider will not work.
This will allow us to select which image from the post gallery to display on the slider.

Function to query Featured posts

Source code



function show_featured_posts($numbers) {


global $post;


//get $numbers of featured posts


$featured_posts_array = get_posts( 'post_type=any&meta_key=_featured_post&meta_value=yes&numberposts=$numbers&post_status=publish');


}

From the above query, we are getting the latest featured posts in post date order. Let we add the image loop in the same function.

Source code



function show_featured_posts($numbers) {


global $post;


//get $numbers of featured posts


$featured_posts_array = get_posts( 'meta_key=_featured_post&meta_value=yes&numberposts=$numbers&post_status=publish');


$output .= '<div class="slider-wrapper theme-default">';


$output .= '<div class="ribbon"></div>';


$output .= '<div id="slider" class="nivoSlider">';


foreach ($featured_posts_array as $post) :  setup_postdata($post);


$nivo_title = "#nivo".get_the_ID(); //assign the postID as title of the image


if ( function_exists("has_post_thumbnail") && has_post_thumbnail() ) {


$output .= get_the_post_thumbnail(get_the_ID(), array(800,400), array( "class" => "post_thumbnail", 'title' => $nivo_title )); }


$caption .= "<div id='nivo".get_the_ID()."' class='nivo-html-caption'>


<h2><a href='".get_permalink()."'>".get_the_title()."</a></h2>


".get_the_excerpt()."


</div>";


endforeach;


$output .= '</div>';


$output .= $caption;


$output .= '</div>';


return $output;


 


//reset WP query


wp_reset_query();


}

So now we got the function to output the selected Featured posts. This function will return the selected featured posts and with this you can integrate any slider of your choice by changing the class name or ID of the div tags.

Next step of our tutorial is importing the necessary nivo files in to the wordpress theme folder.

Put Nivo Slider files in to theme folder

Download latest Nivo Slider version from http://nivo.dev7studios.com/
Copy and paste the ‘themes’ folder from the extract in to your wordpress theme folderyourdomain/wp-content/themes/theme-name/. Copy and paste jquery.nivo.slider.pack.js and nivo-slider.css to your ‘js’ or ‘lib’ folder. You need to be aware of where you are placing the files because you need to set the correct path to these files in the later part.

Include Nivo slider files to the theme

Source code



function include_my_scripts() {


wp_deregister_script( 'jquery' );


wp_register_script( 'jquery', 'http://ajax.googleapis.com/ajax/libs/jquery/1.6/jquery.min.js');


wp_register_script( 'nivopack', get_bloginfo('template_directory').'/js/jquery.nivo.slider.pack.js');


wp_enqueue_script( 'jquery' );


wp_enqueue_script( 'nivopack' );


}    


 


add_action('wp_enqueue_scripts', 'include_my_scripts');


 


add_action('wp_print_styles', 'add_my_stylesheets');


function add_my_stylesheets() {


wp_register_style('nivo_theme_style', get_bloginfo('template_directory').'/themes/default/default.css');


wp_register_style('nivo_main_style', get_bloginfo('template_directory').'/js/nivo-slider.css');


wp_enqueue_style( 'nivo_theme_style');


wp_enqueue_style( 'nivo_main_style');


}


 


//Call the Nivo function in to the footer


add_action('wp_footer', 'nivo_functioncall');


function nivo_functioncall() {


echo '<script type="text/javascript">


$(window).load(function() {


$("#slider").nivoSlider();


});


</script>';


}

The new version of Nivo slider offers 3 set of slider themes ‘default’, ‘orman’ and ‘pascal’. You can change between these themes by changing the theme css file

Source code



wp_register_style('nivo_theme_style', get_bloginfo('template_directory').'/themes/default/default.css');

Place the slider on desired location

Final thing, call the output function show_featured_posts() from your desired location. For example, if you have the index.php as your front page, then paste the following code after the line get_header()in your index.php file.

Source code



<?php if(function_exists('show_featured_posts')) echo show_featured_posts('5'); ?>

Why not implement a shortcode?

Source code



function tg_featured_posts($atts, $content = null) {


extract(shortcode_atts(array(


"numbers" => '5'


), $atts));


echo show_featured_posts($numbers);


}


add_shortcode('featured', 'tg_featured_posts');

Now you can put the shortcode [featured numbers="5"] anywhere in your posts or pages to display the Featured posts Slider, change the numbers value to any number you want.

I hope this tutorial will help you for a good start of creating a WordPress Featured Slider.

If you want this slider with more options and as a wordpress plugin, check the premium plugin by Dev7studios Nivo

http://nivo.dev7studios.com/pricing/

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