Wordpress PageNavi Plugin Doesn't Work on category.php

Question

I have a problem with PageNavi showing 126 pages (for 126 posts -- that part is almost correct), but instead of breaking it down by 10 (expecting 13 pages) it shows all posts in every page. If I change 'numberposts' => 5 it shows the same 5.

Relevant codepart:

<?php wp_pagenavi(); ?>
<?php
$args = array( 'category' => 7, 'numberposts' => -1);
$allpost = get_posts( $args );
    foreach($allpost as $post) : setup_postdata($post); ?>
    <p class="datelist"><a href="<?php the_permalink(); ?>"><?php the_title(); ?></a></p>
<?php endforeach; ?>
<?php wp_pagenavi(); ?>

I can't seem to figure out what's wrong.

Update (Full Code):

<?php
get_header();
?>
<div id="container">
    <div id="content" role="main">
        <h1>something</h1>
        <?php
        $args = array( 'category' => 7, 'numberposts' => -1);
        $allpost = get_posts( $args );
        foreach($allpost as $post) : setup_postdata($post); ?>
        <p class="datelist"><a href="<?php the_permalink(); ?>"><?php the_title(); ?></a></p>
        <?php endforeach; ?>
</div>
</div>
<?php get_footer(); ?>

Working code:

<?php get_header(); ?>
    <div id="container">
            <div id="content" role="main">
            <h1>something</h1>
<?php
global $paged;
if (get_query_var( 'paged' ))
    $my_page = get_query_var( 'paged' );
else {
    if( get_query_var( 'page' ) )
        $my_page = get_query_var( 'page' );
    else
        $my_page = 1;
    set_query_var( 'paged', $my_page );
    $paged = $my_page;
}

$args = array(
    'cat=7',
    'paged' => $my_page,
    'posts_per_page' => 10
);
$my_query = new WP_Query( $args );
while ($my_query->have_posts()) : $my_query->the_post();?>
    <p class="datelist"><a href="<?php the_permalink(); ?>"><?php the_title(); ?></a></p>
<?php endwhile;
wp_pagenavi( array( 'query' => $my_query ) );
wp_reset_query();
?>
        </div>
    </div>
<?php get_footer(); ?>

Answer 1

When you use get_posts you're doing a query by your own, and not using the default query vars generated by WordPress. PageNavi plugin won't work out of the box on custom loops.

As pointed by rbaier4 , you have to use the paged variable. Take care not not mix the default loop with your custom stuff, and to reset the variables after you're done.

global $paged;
if (get_query_var( 'paged' ))
    $my_page = get_query_var( 'paged' );
else {
    if( get_query_var( 'page' ) )
        $my_page = get_query_var( 'page' );
    else
        $my_page = 1;
    set_query_var( 'paged', $my_page );
    $paged = $my_page;
}

// default loop here, if applicable, followed by wp_reset_query();

$args = array(
    // other query params here,
    'paged' => $my_page
);

$my_query = new WP_Query( $args );

// custom loop code

wp_pagenavi( array( 'query' => $my_query ) );
wp_reset_query();

Hope it helps.