Pagination
When there are too much data to be displayed on a single page, a common strategy is to display them in multiple pages and on each page only display a small portion of the data. This strategy is known as pagination.
Yii uses a [[yii\data\Pagination]] object to represent the information about a pagination scheme. In particular,
- [[yii\data\Pagination::$totalCount|total count]] specifies the total number of data items. Note that this is usually much more than the number of data items needed to display on a single page.
- [[yii\data\Pagination::$pageSize|page size]] specifies how many data items each page contains. The default value is 20.
- [[yii\data\Pagination::$page|current page]] gives the current page number (zero-based). The default value is 0, meaning the first page.
With a fully specified [[yii\data\Pagination]] object, you can retrieve and display data partially. For example, if you are fetching data from a database, you can specify the OFFSET and LIMIT clause of the DB query with the corresponding values provided by the pagination. Below is an example,
use yii\data\Pagination;
// build a DB query to get all articles with status = 1
$query = Article::find()->where(['status' => 1]);
// get the total number of articles (but do not fetch the article data yet)
$count = $query->count();
// create a pagination object with the total count
$pagination = new Pagination(['totalCount' => $count]);
// limit the query using the pagination and retrieve the articles
$articles = $query->offset($pagination->offset)
->limit($pagination->limit)
->all();Which page of articles will be returned in the above example? It depends on whether a query parameter named page is given. By default, the pagination will attempt to set the [[yii\data\Pagination::$page|current page]] to be the value of the page parameter. If the parameter is not provided, then it will default to 0.
To facilitate building the UI element that supports pagination, Yii provides the [[yii\widgets\LinkPager]] widget that displays a list of page buttons upon which users can click to indicate which page of data should be displayed. The widget takes a pagination object so that it knows what is the current page and how many page buttons should be displayed. For example,
use yii\widgets\LinkPager;
echo LinkPager::widget([
'pagination' => $pagination,
]);If you want to build UI element manually, you may use [[yii\data\Pagination::createUrl()]] to create URLs that would lead to different pages. The method requires a page parameter and will create a properly formatted URL containing the page parameter. For example,
// specifies the route that the URL to be created should use
// If you do not specify this, the currently requested route will be used
$pagination->route = 'article/index';
// displays: /index.php?r=article%2Findex&page=100
echo $pagination->createUrl(100);
// displays: /index.php?r=article%2Findex&page=101
echo $pagination->createUrl(101);Tip: You can customize the name of the
pagequery parameter by configuring the [[yii\data\Pagination::pageParam|pageParam]] property when creating the pagination object.
