codeigniter:分页逻辑每页显示2个列表 [英] codeigniter: Pagination logic to show 2 lists per page

问题描述

我在控制器中有一个分页页面，我对视图中每页列出2个数据感到困惑.我正在使用的控制器代码如下:

I am having a pagination page in my controller, i am kind of puzzled in listing 2 data per page on my view. The controller code which i am using is as follows:

public function newsletter()
{
    $this->load->library('pagination');
    $config = array();

    $config["base_url"] = base_url() . "index.php/welcome/newsletter";
    $this->load->model('newsletter_model');
    $total_row = $this->newsletter_model->record_count();
    $config["total_rows"] = $total_row;
    $config["per_page"] = 2;  // per page 2 records
    $config['use_page_numbers'] = TRUE;
    $config['num_links'] = $total_row;
    $config['cur_tag_open'] = '&nbsp;<a class="current">';
    $config['cur_tag_close'] = '</a>';

    $config['page_query_string'] = FALSE;
    $config['next_link'] = 'Next';
    $config['prev_link'] = 'Previous';

    $this->pagination->initialize($config);
    if($this->uri->segment(3)){  
    $page = ($this->uri->segment(3)) ; 
    }
    else{ 
    $page = 1;
    } 
    $this->load->model('newsletter_model');
    $data["results"] = $this->newsletter_model->fetch_data($config["per_page"], $page); 
    $str_links = $this->pagination->create_links();
    $data["links"] = explode('&nbsp;',$str_links );

    $this->load->model('newsletter_model');
    $this->load->view('newsletter/newsletter',$data);
}

使用上面的代码，我每页可获得2条记录，但我无法理解分页背后的逻辑.谁能解释我在codeigniter pagination中工作的逻辑以及我的工作本身，因为这对我来说很容易理解.

With the above code i am getting 2 records per page as i intended, but i could not understand the logic behind the pagination. can anyone explain me the logic worked in codeigniter pagination, with my work itself as it would be handy for me to understand it.

我的模型代码如下:

  public function fetch_data($limit, $id)
   { 

    $this->db->select('*');
    $this->db->from('ins_newsletter');
    $this->db->order_by('nl_id', 'desc');
    $this->db->limit($limit,$id);
    $query = $this->db->get();

    return $query->result_array();

}
public function record_count() 
{
    return $this->db->count_all("ins_newsletter");
}

推荐答案

CI的Paginator类仅为您生成分页链接.

CI's Paginator class only generates pagination links for you.

记录分页"逻辑发生在这里:

The "record pagination" logic happens here:

$this->db->limit($limit, $offset);

$limit是要提取的记录数，$offset是要返回的第一行的偏移量.

$limit is the number of records to fetch, $offset is the offset of the first row to return.

要获取前两个记录，我们将设置$limit = 2，$offset = 0

To fetch the first two records, we will set $limit = 2, $offset = 0

CI可转换为SQL，如:

CI translates into SQL like:

SELECT ...... FROM ins_newsletter LIMIT 0, 2;

要获取记录编号3和4，我们将设置$limit = 2，$offset = 2

To fetch record number 3 and 4, we will set $limit = 2, $offset = 2

CI可转换为SQL，如:

CI translates into SQL like:

SELECT ...... FROM ins_newsletter LIMIT 2, 2;

---

您的代码中有一个小错误.

There is a small bug in your code.

第1页的偏移量应为0，第2页的偏移量应为2，第3页的偏移量应为4，第4页的偏移量应为8，第5页的偏移量应为...等等.

The offset should be 0 for page 1, 2 for page 2, 4 for page 3, 6 for page 4, 8 for page 5...and so on.

public function fetch_data($limit, $page)
{
    $offset = ($page - 1) * $limit;
    ...
}

我建议您将第二个参数更改为$page而不是$id.

And I would suggest you to change the second param to $page instead of $id.

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