Yii2 - GridView - How Sorting works? - php

Question

I am trying to understand how sorting works in GridView by means of generating a default CRUD application. Sorting happens after clicking the respective attribute which is the table header. The column name is attached to the url with the variable sort and on click the action method is invoked, but what I am wondering is that the action method which is mentioned in the url with the actual variable $sort is not present in the controller.
Below is a example
The url looks like the below,
/advanced/frontend/web/index.php?r=site%2Findex&sort=customer_user_name2
But there is no corresponding action method in the site controller as
function actionIndex($sort);

Answer 1

Consider following example
We have Passenger CRUD
Consider Passenger - a model and PassengerSearch - its corresponding search model
Passenger attribute are id, name and country_name
In PassengerController.php
<?php
...
public function actionIndex()
{
$searchModel = new PassengerSearch();
$dataProvider = $searchModel->search(Yii::$app->request->queryParams);
return $this->render('index', [
'searchModel' => $searchModel,
'dataProvider' => $dataProvider,
]);
}
...
?>
Search string a in name column
and sort id column in desc order
Look at the url generated, it would be like
`http://localhost/YII2proj/passenger/index?PassengerSearch%5Bid%5D=&PassengerSearch%5Bname%5D=a&PassengerSearch%5Bcountry_name%5D=&sort=-id`
In human readable format
http://localhost/YII2proj/passenger/index?
PassengerSearch[id]=&
PassengerSearch[name]=a&
PassengerSearch[country_name]=&
sort=-id
Observe PassengerSearch is a array. Please refer - How to send a array in url request?
Focus on the parameter to search() method of object PassengerSearch class it is Yii::$app->request->queryParams
Before
$dataProvider = $searchModel->search(Yii::$app->request->queryParams);
line, insert following code
echo '<pre>';
print_r(Yii::$app->request->queryParams);
echo '</pre>';
die;
and see the result
Array
(
[PassengerSearch] => Array
(
[id] =>
[name] => a
[country_name] =>
)
[sort] => -id
)
If no searching sorting done, then this array will be empty
So this line does your code like following
<?php
if(isset($_GET['sort']) || isset($_GET['PassengerSearch']['id'] ...)
{
// validate it because what if I changed url like
// `http://localhost/YII2proj/passenger/index?PassengerSearcasdh[dfsid]=&PassengerSearch[name]=a&PassengerSearch[country_name]=&sorsfdft=-idadlashdfhls`
// ie some scrap value
// If error returned from validate function, default sorting is done, and malformed search param is not set
// if success, fill up that array
}
?>
Then in search Model load() is the hero.
Where and how above code is done? - Refer Model and load()
Searching is done via andFilterWhere after loading ie load() and that you can see in search() method
Hope you got the idea behind searching and sorting.