|
|
|
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
|
|
|
|
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,
|
|
|
|
|
|
|
|
```php
|
|
|
|
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,
|
|
|
|
|
|
|
|
```php
|
|
|
|
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,
|
|
|
|
|
|
|
|
```php
|
|
|
|
// 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/index&page=100
|
|
|
|
echo $pagination->createUrl(100);
|
|
|
|
|
|
|
|
// displays: /index.php?r=article/index&page=101
|
|
|
|
echo $pagination->createUrl(101);
|
|
|
|
```
|
|
|
|
|
|
|
|
> Tip: You can customize the name of the `page` query parameter by configuring the
|
|
|
|
[[yii\data\Pagination::pageParam|pageParam]] property when creating the pagination object.
|