How to get posts by content?

Question

I found the following codes to get post details. However, it is not possible to get the posts by content. Does any one has any ideas?

get_posts()

//// get post ////
$args = array(
    'numberposts'     => -1, // number of posts to display; display all: -1.
    'offset'          => 0,
    // 'category'        => , // post category ID
    'orderby'         => 'post_date',
    'order'           => 'DESC', // Latest post first: 'ASC'; Olderest post first: 'DESC'
    // 'include'         => ,
    // 'exclude'         => ,
    // 'meta_key'        => ,
    // 'meta_value'      => ,
    'post_type'       => 'post', // get post type
    // 'post_mime_type'  => ,
    // 'post_parent'     => ,
    // 'post_status'     => 'publish'
);

// http://codex.wordpress.org/Class_Reference/WP_Query#Custom_Field_Parameters
$posts_array = get_posts( $args );
foreach( $posts_array as $post ) : setup_postdata($post);
    echo "<li><a href='" . the_permalink() . "'>" . the_title() .
         "</a>" .
         $post->blog_ID . 
         $post->post_date . 
         $post->post_title . 
         $post->pubtimes . 
         $post->post_author . 
         $post->post_content . 
         $post->post_excerpt . 
         $post->post_status;
        "</li>";
endforeach;

Answer 1

You have to extend the db query to search in the post_content column. There is a filter: 'posts_where' you can use.

I would write a simple wrapper for get_posts() to extends its arguments an run the filter once. Example:

class T5_Posts_By_Content
{
    protected static $content = '';

    protected static $like    = TRUE;

    /**
     * Mapper for get_posts() with extra arguments 'content' and 'like'
     *
     * 'content' must be a string with optional '%' for free values.
     * 'like' must be TRUE or FALSE.
     *
     * @param array $args See get_posts.
     * @return array
     */
    public static function get( $args )
    {
        if ( isset ( $args['content'] ) )
        {
            // This is TRUE by default for get_posts().
            // We need FALSE to let the WHERE filter do its work.
            $args['suppress_filters'] = FALSE;
            self::$content            = $args['content'];
            add_filter( 'posts_where', array ( __CLASS__, 'where_filter' ) );
        }

        isset ( $args['like'] ) and self::$like = (bool) $like;

        return get_posts( $args );
    }

    /**
     * Changes the WHERE clause.
     *
     * @param string $where
     * @return string
     */
    public static function where_filter( $where )
    {
        // Make sure we run this just once.
        remove_filter( 'posts_where', array ( __CLASS__, 'where_filter' ) );

        global $wpdb;
        $like  = self::$like ? 'LIKE' : 'NOT LIKE';
        // Escape the searched text.
        $extra = $wpdb->prepare( '%s', self::$content );

        // Reset vars for the next use.
        self::$content = '';
        self::$like    = TRUE;

        return "$where AND post_content $like $extra";
    }
}

To find the last five posts containing the string resized write:

$args = array(
    'content' => '%resized%'
);
$posts = T5_Posts_By_Content::get( $args );

To get the last five posts not containing resized:

$args = array(
    'content' => '%resized%',
    'like'    => FALSE
);
$posts = T5_Posts_By_Content::get( $args );

Answer 2

I can't think of an elegant way off the top of my head, I'm not sure if it's even possible using core functions, but the SQL you would want to use would be something like this (note that this is pseudocode):

SELECT  `ID` 
FROM  `$wpdb->posts` 
WHERE  `post_content` LIKE  '%search term%'

This will return all the IDs of posts that SQL thinks relates to your search term.