How to shorten pagination in PHP?

Here I leave you an option based on your code and with minimal changes on it.

The idea is quite simple (although I don't know if I will explain it well) and it consists of the following: always show a maximum of 10 links that will start with the unit and end with said unit+9 (or the total pages if unit+9 is elderly). That means that for page 5, the links displayed will be from 1 to 10; for page 13, the links will be from 11 to 20, etc.

To do this, it is necessary to: calculate what will be the first number and the last number to be displayed, and make the loop be only between them. Then, when showing the arrows, it will be necessary to check if the first page is less than 10 (in which case the arrow to the left will not be shown) or if the last page is equal to the total number of pages (in which case it will not be shown). the arrow to the right).

Here is an example of how it would be done:

Note- I'm (almost) convinced that you can somehow simplify the calculation of the first and last, but my brain is fried right now (I had a super-complicated calculation initially and have narrowed it down to this)

<?php
// calculamos la primera y última página a mostrar
$primera = $pagina - ($pagina % 10) + 1;
if ($primera > $pagina) { $primera = $primera - 10; }
$ultima = $primera + 9 > $total_paginas ? $total_paginas : $primera + 9; 
?>
<nav aria-label="Page navigation" class="text-center">
     <ul class="pagination">
        <?php
        if ($total_paginas > 1) {
            // comprobamos $primera en lugar de $pagina
            if ($primera != 1)
                echo '<li><a href="'.$url.'?pagina='.($primera-1).'" aria-label="Previous"><span aria-hidden="true">&laquo;</span></a></li>';

            // mostramos de la primera a la última
            for ($i = $primera; $i <=$ultima; $i++){
                if ($pagina == $i)
                    echo '<li class="active"><a href="#">'.$pagina.'</a></li>';
                else
                    echo '<li><a href="'.$url.'?pagina='.$i.'">'.$i.'</a></li>';
            }

            if ($i <= $total_paginas)
                echo '<li><a href="'.$url.'?pagina='.($i).'"><span aria-hidden="true">&raquo;</span></a></li>';
        }
        ?>
      </ul>
</nav>

Doing something similar to what Alvaro did, taking your code as a base, this is a slightly different version, the goals are:

• Show the 5 pages before and the 5 following the current one
• Show first page if not in previous group
• Show the last page if it is not in the group of the first point

The idea of ​​this answer is to add an option for those who encounter this question "in the future".

$primera = ($pagina - 5) > 1 ? $pagina - 5 : 1;
$ultima = ($pagina + 5) < $total_paginas ? $pagina + 5 : $total_paginas;

if ($total_paginas > 1) {

    // flecha anterior
    if ($pagina != 1) {
        echo '<li><a href="'.$url.'?pagina='.($pagina-1).'" aria-label="Previous"><span aria-hidden="true">&laquo;</span></a></li>';
    }

    // si la primera del grupo no es la pagina 1, mostramos la 1 y los ...
    if ($primera != 1) {
        echo '<li><a href="'.$url.'?pagina=1">'.$i.'</a></li>';
        echo '<li>...</li>';
    }

    // mostramos la página actual, las 5 anteriores y las 5 posteriores
    for ($i = $primera; $i <= $ultima; $i++){
        if ($pagina == $i)
            echo '<li class="active"><a href="#">'.$pagina.'</a></li>';
        else
            echo '<li><a href="'.$url.'?pagina='.$i.'">'.$i.'</a></li>';
    }

    // si la ultima del grupo no es la ultima (lol), mostramos la ultima y los ...
    if ($ultima != $total_paginas) {
        echo '<li>...</li>';
        echo '<li><a href="'.$url.'?pagina='.$total_paginas.'">'.$i.'</a></li>';
    }

    // flecha siguiente
    if ($pagina != $total_paginas) {
        echo '<li><a href="'.$url.'?pagina='.($pagina+1).'"><span aria-hidden="true">&raquo;</span></a></li>';
    }

}

The same is to change a little the concept of what you use now. I do it in such a way that the pagination is done in a class and then in the PHP, I call the pagination.

I have this file for a connection PDO, but if you search the Internet, you will surely find it for mysqlormysqli

pagination.php

class PDO_Pagination
{
  public $connection;
      public $total;
      public $page;
      public $total_page;
      public $start_row;
      public $item;
      public $max_pages;
      public $max_rows;
      public $step;
      public $max;
      public $param;
      public $btn_first_page;
      public $btn_last_page;
      public $btn_next_page;
      public $btn_back_page;
      public $btn_page;
      public $btn_active;

      public function __construct($connection) {
      $this->btn_first_page = 'Previous';
      $this->btn_last_page = 'Last';
      $this->btn_next_page = 'Next';
      $this->btn_back_page = 'Back';
      $this->btn_page = 'Pag.';
      $this->btn_active = 'active';
      return $this->connection = $connection;
  }

  public function rowCount($query){
      $query = $this->connection->prepare($query);
      $query->execute();
      $this->total = $query->rowCount();
  }

      public function config($max_pages, $max_rows){
      $this->start_row = 0;
      $this->item = 0;
      $this->max_pages = $max_pages;
      $this->max_rows = $max_rows;
      $this->total_page = $this->total / $this->max_rows;

      if (isset($_GET["page"])){
          $this->page = $_GET["page"];
          if ($this->page < 0 || !preg_match("/^([0-9])+$/", $this->page)){
              return;
          }

          $this->start_row = $this->page * $this->max_rows;

          $this->item = $_GET["item"];
          if ($this->item < 0  || !preg_match("/^([0-9])+$/", $this->item)){
              return;
          }

          $this->max_pages = $this->max_pages + $this->max_rows;

          $this->max = $_GET["max"];
          if ($this->max < 0  || !preg_match("/^([0-9])+$/", $this->max)){
              return;
          }
          $this->max_pages = $this->max;
      }


      if(isset($_GET["next_page"])){
          $this->page = $_GET["next_page"];
          if ($this->page < 0  || !preg_match("/^([0-9])+$/", $this->page)){
              return;
          }

          $this->start_row = $this->page * $this->max_rows;

          $this->item = $_GET["item"];
          if ($this->item < 0  || !preg_match("/^([0-9])+$/", $this->item)){
              return;
          }

          $this->max = $_GET["max"];
          if ($this->max < 0  || !preg_match("/^([0-9])+$/", $this->max)){
              return;
          }
              $this->max_pages = $this->max + 1;
          }

          if(isset($_GET["back_page"])){
          $this->page = $_GET["back_page"] - 1;
          if ($this->page < 0  || !preg_match("/^([0-9])+$/", $this->page)){
              return;
          }
          $this->start_row = $this->page * $this->max_rows;

          $this->item = $_GET["item"] - 1;
          if ($this->item < 0  || !preg_match("/^([0-9])+$/", $this->item)){
              return;
          }

          $this->max = $_GET["max"];
              if ($this->max < 0  || !preg_match("/^([0-9])+$/", $this->max)){
              return;
          }

          $this->max_pages = $this->max - 1;
      }

          if (isset($_GET["previous"])){
          $this->max_pages = $this->max_pages;
          $this->start_row=0;
          $this->item = 0;
      }
  }

  public function pages($class=''){

  if($this->item >= 1){
          echo "<a class='$class'  href='?previous=1".$this->param."'>$this->btn_first_page</a>";
          echo "<a class='$class'  href='?back_page=$this->page&item=$this->item&max=$this->max_pages".$this->param."'>$this->btn_back_page</a>";
      }
      for($x = $this->item; $x < $this->max_pages; $x++){
      while($x * $this->max_rows < $this->total){
          $p = $x+1;
          $this->page == $p-1 ? $active = ' ' . $this->btn_active : $active = null;
          echo "<a class='$class$active' href='?page=$x&item=$this->item&max=$this->max_pages".$this->param."'>$p</a>";
          break;
      }
  }

      $numbers = $this->page+1;
      echo "<span class='$class'>$this->btn_page <b>$numbers</b></span>";

      if ($this->max_pages * $this->max_rows < $this->total){
      $this->page = $this->page+1;
      $this->item = $this->item + 1;
      echo "<a class='$class' href='?next_page=$this->page&item=$this->item&max=$this->max_pages".$this->param."'>$this->btn_next_page</a>";

      $this->page = round($this->total_page - 1);
      $this->item = round($this->total_page - $this->max_pages);
      $this->max = round($this->total_page);
      echo "<a class='$class'  href='?page=$this->page&item=$this->item&max=$this->max".$this->param."'>$this->btn_last_page</a>";
  }
  }
}

The call in the code would be:

<?php
$connection = dbConnect ();
$pagination = new PDO_Pagination($connection);
$pagination->rowCount("SELECT * FROM noticias WHERE publicado=1");
$pagination->config(5, 30); 
$sql = "SELECT * FROM noticias WHERE publicado=1 ORDER BY fecha DESC LIMIT $pagination->start_row,
$pagination->max_rows";
$query = $connection->prepare($sql);
$query->execute();
$model = array();
while($rows = $query->fetch())
 {
  $model[] = $rows;
}
 foreach($model as $row){
  echo "<li class='li_noticias'>";
  echo "<a href='".$row['idref'].".html' rel='follow'>";
  //echo "<a href='noticias2.php?ref=".$row['idref']."' rel='follow'>";
   echo $row['titulo'];
   echo "</a>";
   echo "</li>";
 }
?>