Transient pagination not working properly

Question

So I wrote the following to create a transient:

$wp_object_i_created = new WP_Query('cat=1');
set_transient('category_one_posts', $wp_object_i_created, 60*60*1);

Ok so then I decided "Ya know lets walk through this and spit out the posts."

So I did the following:

if(false !== get_transient('category_one_posts')){
    $posts_inside = get_transient('category_one_posts');
    if($posts_inside->have_posts()){
        while($posts_inside->have_posts()){
            $posts_inside->the_post();
            // Display your posts in some maner.
        }
        echo get_next_posts_link('« Older Entries', $max_pages);
        echo get_previous_posts_link('Newer Entries »', $max_pages);
    }
 }

Now the pagination works - here's the catch - It works in a really failed way. So I have it set to display 5 posts per page.

So if I go to my link: http://localhost/wordpress/?page_id=1667 I see my 5 posts and at the bottom my two links - one for older, one for newer. Woot. But if I click on the button "Older Entries" to go back, so my link now looks like: http://localhost/wordpress/?page_id=1667&paged=2 I see that were on page two, I can go one page forward and so on - BUT the posts are the same, they never updated.

Now regular queries done to get specific posts based on specific parameters, or even just the regular WordPress loop - their pagination all work as expected, you go to page two, you get a different set of posts then that on page one - woot! - we work.

But transient based pagination does not work.

Why?

Answer 1

Short answer: You are making the same query no matter what page you are, but you're expecting a different result.

Long answer: The query should be different for second page, having paged=2, so your query (and transients) with pagination should look like this:

$paged_var = get_query_var( 'paged' ) ? get_query_var( 'paged' ) : 1;

if ( get_transient( 'category_one_posts-' . $paged_var ) == false ) {
    $posts_inside = new WP_Query(
        array(
             'cat' => 1,
             'paged' => $paged_var
        )
    );
    set_transient( 'category_one_posts-' . $paged_var, $posts_inside, 60*60*1 );
} else {
    $posts_inside = get_transient( 'category_one_posts-' . $paged_var );
}

if ( $posts_inside->have_posts() ) {
    while( $posts_inside->have_posts() ) {
        $posts_inside->the_post();
        // Display posts.
    }

    echo get_next_posts_link( __( 'Next', 'textdomain'), $posts_inside->max_num_pages );
    echo get_previous_posts_link( __( 'Previous', 'textdomain'), $posts_inside->max_num_pages );
}