WP pagination in rest api - wordpress

Question

we have made a custom api to get all the post in descending order and we want to add pagination in that api, I have read other questions and answers also but didnt get any idea so can some one explain me with a simple code with pagination so that I can understand how it works.
This is my code so how can I add pagination can anyone explain to me because I searched other questaion also but I didnt get any idea.
define('API_ENDPOINT_VERSION',1);
//flush the rewrite rules on plugin activation
function apiendpoint_activate()
{
flush_rewrite_rules();
}
register_activation_hook(__FILE__,'apiendpoint_activate');
function apiendpoint_register_endpoints(){
register_rest_route(
'api/v1',
'/post',
[
'methods' => 'GET',
'callback' =>'api_get_post',
]
);
}
add_action('rest_api_init','apiendpoint_register_endpoints');
function api_get_post($request){
$ar = array( 'post_type'=>'post',
'posts_per_page'=>15,
'orderby' => 'date',
'order' => 'DESC',
);
$posts = get_posts($ar);
//var_dump($posts);
//exit;
$a = array();
if($posts){
foreach ($posts as $post) {
$a[]= array(
'title'=>$post->post_title,
'link'=>get_the_permalink($post->ID),
'category'=>get_the_category($post->ID),
'published_date'=>get_the_date('l, F j, Y',$post->ID),
'guid'=>$post->guid,
'image'=>get_the_post_thumbnail_url($post->ID,'large'),
'description'=>$post->post_excerpt,
'source'=>"Nepaljapan"
//'img'=>$img
);
}
return $a;
}
}

Answer 1

Try the below code:
define('API_ENDPOINT_VERSION', 1);
//flush the rewrite rules on plugin activation
function apiendpoint_activate() {
flush_rewrite_rules(); } register_activation_hook(__FILE__, 'apiendpoint_activate');
function apiendpoint_register_endpoints() {
register_rest_route(
'api/v1',
'/post',
[
'methods' => 'GET',
'callback' => 'api_get_post',
]
);
} add_action('rest_api_init', 'apiendpoint_register_endpoints');
function api_get_post($request) {
$ar = array('post_type' => 'posts',
'posts_per_page' => 15,
'orderby' => 'date',
'order' => 'DESC',
'paged' => ($_REQUEST['paged'] ? $_REQUEST['paged'] : 1)
);
$posts = get_posts($ar); //var_dump($posts); //exit; $a = array();
if ($posts) {
foreach($posts as $post) {
$a[] = array(
'title' => $post -> post_title,
'link' => get_the_permalink($post -> ID),
'category' => get_the_category($post -> ID),
'published_date' => get_the_date('l, F j, Y', $post -> ID),
'guid' => $post -> guid,
'image' => get_the_post_thumbnail_url($post -> ID, 'large'),
'description' => $post -> post_excerpt,
'source' => "Nepaljapan"
//'img'=>$img
);
}
return $a; }
}
Call API call as below:
/wp-json/api/v1/post?paged=1
Increase the paged value by 1 to get next paging posts.
Hope this helps!